Updated on 2022/09/28

写真a

 
SATO, Yasuhiko
 
Affiliation
Faculty of Science and Engineering, School of Creative Science and Engineering
Job title
Professor

Concurrent Post

  • Faculty of Science and Engineering   Graduate School of Creative Science and Engineering

Research Institute

  • 2020
    -
    2022

    理工学術院総合研究所   兼任研究員

Degree

  • 北海道大学   博士(工学)

Research Experience

  • 2018.04
    -
    Now

    Waseda University

  • 2018.04
    -
    2020.03

    北海道大学大学院   客員教授

  • 2007.04
    -
    2018.03

    Hokkaido University

  • 2005.04
    -
    2007.03

    北海道大学大学院   助教授

  • 1997.04
    -
    2005.03

    北海道大学大学院   助手

  • 1994.01
    -
    1997.03

    Hokkaido University

▼display all

Professional Memberships

  •  
     
     

    aci

  •  
     
     

    fib

  •  
     
     

    資源素材学会

  •  
     
     

    コンクリート工学会

  •  
     
     

    PC工学会

  •  
     
     

    材料学会

  •  
     
     

    土木学会

▼display all

 

Research Areas

  • Safety engineering

  • Civil engineering material, execution and construction management

  • Structure engineering and earthquake engineering

  • Social systems engineering

Research Interests

  • design

  • concrete

Papers

  • Experimental and numerical study of structural effects of anisotropic frost damage on reinforced concrete beams

    Takeru Kanazawa, Yasuhiko Sato, Ryosuke Takahashi

    Journal of Advanced Concrete Technology   19 ( 1 ) 14 - 25  2021

     View Summary

    Unlike plain concrete, frost damaged reinforced concrete (RC) exhibits anisotropy because of the presence of reinforcing bars. The resultant mechanical responses are influenced strongly by the loading direction. Therefore, to ascertain the mechanical behavior up to failure of RC beams subjected to freeze-thaw action and subsequent mechanical loading, anisotropic damage models of frost-damaged RC elements were assessed in this study using three-dimensional nonlinear finite element analysis (3D-NLFEA), which revealed that the anisotropic damage affected load-deflection responses and played a key role in failure modes that differed from those of an undamaged RC beam. This paper is the English translation from the authors' previous work [Kanazawa, T., Sato, Y. and Takahashi, R., (2019). "Frost damage of reinforced concrete beams and analytical evaluation of its static failure behavior." Journal of Japan Society of Civil Engineers. Ser. E2 (Materials and Concrete Structures), 75(4), 293-307. (in Japanese)].

    DOI

  • Fatigue behavior of air-entrained high strength concrete with blast furnace slag fine aggregates under freezing and thawing

    M. A. Farooq, Y. Sato, K. Niitani, H. Yokota

    Lecture Notes in Civil Engineering   101   2025 - 2035  2021

     View Summary

    This experimental study investigates the compressive fatigue behavior of air-entrained (AE) concrete with blast furnace slag (BFS) fine aggregates subjected to freeze-thaw cycles (FTC). The fatigue tests were carried out on cylindrical specimens of intact and frost-damaged AEBFS concrete and the results are compared with those of AE high strength (HS) normal concrete using crushed sand. The strain measurements are used to discuss the damage progress under fatigue loading. The results reveal that although the static compressive strength of AEBFS concrete is slightly less than AEHSN concrete, the fatigue life of AEBFS concrete is longer than that of AEHSN concrete. No significant effect of FTC is found on the fatigue behavior of each concrete due to very low frost damage. Moreover, it is found that overall the fatigue life of AEHS concrete is longer than that of non-AE high strength concrete from literature and this difference is pronounced with the reduction in maximum stress level.

    DOI

  • Experimental investigation of monotonic behavior and stress-strain models of AE and non-AE high strength concrete with BFS fine aggregates under freezing and thawing

    Muhammad Aboubakar Farooq, Yasuhiko Sato, Kyoji Niitani

    Construction and Building Materials   249  2020.07

     View Summary

    This study is attempted to investigate the change in mechanical properties and to formulate the stress-strain models of air-entrained (AE) and non-air entrained high strength concrete with blast furnace slag (BFS) sand as fine aggregates under freezing and thawing. The freeze-thaw (FT) test was carried out on the concrete specimens followed by static compression tests and the results are compared with those of AE normal strength normal (AENSN) and AE high strength normal (AEHSN) concrete using crushed sand. The experimental results disclose that overall the rate of plastic strain development due to freezing and thawing in non-AE high strength concrete is higher than that of AE high strength concrete, but less than that of companion normal strength concrete. Consequently, the mechanical properties of non-AE concrete deteriorate at higher rate in comparison with AE concrete under freezing and thawing. However, no significant reduction in mechanical properties of AEBFS and AEHSN concrete is observed compared to AENSN concrete. Moreover, it is found that the Young's modulus of frost-damaged concrete degrades rapidly than the compressive strength. Thereafter, the stress-strain relationships for AE and non-AE high strength concrete under monotonic loading are formulated based on elasto-plastic and fracture concept. Based on the experimental data, the relationships for fracture parameter and plastic strain development of high strength concrete under monotonic loading are developed. The stres-strain relationships calculated by the proposed model are compared with the experimental ones.

    DOI

  • Effects of bond configurations on flexural response of RC beams externally strengthened with CFRP sheets

    Jianguo Dai, Keisuke Sumiyoshi, Tamon Ueda, Hiroshi Yokota, Yasuhiko Sato

    Composites in Civil Engineering, CICE 2006     39 - 42  2020

     View Summary

    This paper investigates experimentally how various bond configurations influence the flexural response of FRP-strengthened RC beams. A total of seven beams(200×200×2200mm) were tested. One was the reference without strengthening. Two were strengthened with CFRP sheets using hard and soft adhesive bonding, respectively, along the whole test span. The remaining four were applied a combination of hard and soft adhesives but in two different ways. One way is to use the soft adhesive at the flexure-dominating zone only and another is to use it for the shear-dominating zone only. Pair tests were conducted for these four specimens under both normal and low temperature (- 10°C). It is revealed that a sole use of soft adhesive improves the ultimate member strength and ductility but leads to a loss of stiffness. Using the soft adhesive at the flexure-dominating zone can not improve the member strength but improve the member ductility only. However, use of hard adhesive at the flexure-dominating zone and the soft one for the remaining parts can improve the member strength and ductility while avoiding loss of member stiffness. This test program provides an in-depth understanding of the debonding mechanisms in the FRP-strengthened RC beams. In addition, it is verified that that a low temperature of -10°C does not influence the global flexural response of FRP strengthened beams using the combined bonding system.

  • Basic bond characteristics of frp strand sheet-concrete interface with polyurea resin

    Mitsuhiko Ozaki, Akira Kobayashi, Yasuhiko Sato, Masaki Arazoe, Akihiro Tateishi, Atsuya Komori

    Journal of Advanced Concrete Technology   18 ( 9 ) 505 - 520  2020

     View Summary

    Aiming at improving bond strengths between FRP sheet and concrete, the FRP sheet bonding method using high elongation elastic resin as a buffer layer was developed. In this study, bonding tests was conducted to clarify the basic bond characteristics of FRP strand sheet-concrete interface with a polyurea resin. As a result of the bonding tests, it was found that the use of the polyurea resin as a buffer layer significantly improved the bond strength and the interfacial fracture energy between FRP sheets and concrete. In addition, bond stress-slip relationships with a polyurea resin were proposed. Finally, numerical analyses of bonding CFRP strand sheets and concrete were conducted so as to verify validity of the proposed bond stress-slip relationships. This paper is an extended version in English from the authors' previous work [Kobayashi, A., Ozaki, M., Sato, Y., Arazoe, M., Tateishi, A. and Komori, A., (2020). “Study on bonding behavior of FRP sheets and concrete bonded with high elongation elastic resin.” Journal of Structural Engineering, JSCE, 66A, 855-867. (in Japanese)].

    DOI

  • Development of fatigue life prediction for RC slabs under traveling wheel-type loading

    K. Takeda, Y. Sato

    Life-Cycle Analysis and Assessment in Civil Engineering: Towards an Integrated Vision - Proceedings of the 6th International Symposium on Life-Cycle Civil Engineering, IALCCE 2018     1851 - 1856  2019

     View Summary

    In this study, authors investigated a fatigue life prediction method for RC slabs considering effects of support condition and stepped incremental load based on experimental data of traveling wheel-type loading test. At first, to properly predict the fatigue life of RC slabs under constant cyclic loading test, a coefficient which represents influence of support condition was introduced to previous prediction method that authors had proposed. The modified method can cover three types of support conditions; simply support along longitudinal direction and elastic support along transverse direction, simple support along longitudinal direction and free ends along transverse direction, and simple support along all directions. Besides considering fatigue damage caused by preceding loading block as reduction of shear strength due to cyclic loading, a new evaluation method for stepped incremental loading test was proposed.

  • An analytical study on effects of loading history to shear behavior of RC beams under cyclic loading

    Kyoko Takeda, Yasuhiko Sato

    Proceedings of the fib Symposium 2019: Concrete - Innovations in Materials, Design and Structures     1677 - 1683  2019

     View Summary

    Studying about fatigue in RC beams without stirrup is one of valid approaches to investigate fatigue problem in RC slabs because the transverse cracked slab can be considered as plural RC beams lined up in parallel. Therefore, in this paper, authors tried to clarify the fatigue damage in RC beams keeping the problem of RC slabs in mind. Non-linear three-dimensional finite element analysis (3D-FEA) of RC beams without stirrup is conducted under three types of loading conditions; static load, fatigue load and variable amplitude fatigue load. By comparing static and fatigue analysis results, authors examine the principal compressive stress distribution and the stiffness reduction. This paper presents that static and fatigue loading showed different trends in both the stress distribution and stiffness reduction. It can be also revealed that when variable amplitude load with different two load blocks is given in fatigue analysis, the cyclic loading in the first load block influences on the decreasing rate of stiffness.

  • Investigation on structural behavior of existing prestressed post-tensioned concrete bridge superstructure

    Yasuhiko Sato, Wanakorn Prayoonwet, Yoshinobu Oshima

    Proceedings of the fib Symposium 2019: Concrete - Innovations in Materials, Design and Structures     1021 - 1028  2019

     View Summary

    The authors conducted on-site load test and 3D Finite Element Analyses (3D-FEA) of an existing prestressed post-tensioned concrete bridge with four post-tensioned T-girders, whose span length was 36 m, constructed in 1960 so as to clarify structural behaviour and its capacity of the bridge superstructure. It was found that the 3D-FEA combined with the linear surface spring elements which represents restraint of adjacent members can well simulate the actual structural behavior, the capacity and failure mode. Besides it is also discussed about the reason why capacity of a girder in superstructure becomes greater than a single girder with same cross-sectional properties.

  • Weakly singular BIEM for analysis of cracks embedded in symmetric elastic whole space

    T. N. Pham, J. Rungamornrat, W. Pansuk, Y. Sato

    Lowland Technology International   20 ( 2 ) 169 - 186  2018

     View Summary

    In this paper, a weakly singular boundary integral equation method is developed for the stress analysis of an anisotropic, linearly elastic, cracked whole space possessing a plane of symmetry. This study should offer an alternative powerful tool essential for the modeling of both near-surface and deeply embedded defects in a rock/soil medium. A system of governing equations is established using a pair of weakly singular, weakform, displacement and traction integral equations for the cracked whole space along with the symmetric condition. The final equations contain only unknown crack-face data in a lowerhalf of the whole space. In addition to their capability to treat cracks of arbitrary shape, material anisotropy and general loading conditions, all involved kernels are weakly singular allowing all integrals to be interpreted in the sense of Riemann. A symmetric Galerkin boundary element method together with the Galerkin approximation is implemented to solve the governing integral equations for the unknown crack-face data. To further enhance the accuracy and efficiency of the proposed scheme, special basis functions are introduced to approximate the near-front field and the interpolation technique is adopted to evaluate all kernels for generally anisotropic materials. The solved crack-face displacement data is then utilized to postprocess for the essential fracture information along the crack front. Various scenarios are employed to verify the proposed technique and a selected set of results is presented to demonstrate its accuracy and computational robustness.

  • Shear capacity of high performance fiber reinforced concrete I-beams

    Withit Pansuk, Thuc N. Nguyen, Yasushiko Sato, J. A. Den Uijl, J. C. Walraven

    Construction and Building Materials   157   182 - 193  2017.12

     View Summary

    An experimental program was carried out to investigate the shear capacity of High-Performance Fiber-Reinforced Concrete (HPFRC) I-beams. The main parameters were assigned as the fiber content and presence of shear reinforcement. To study the effect of these main parameters on the shear capacity, testing of six I-beams and other control specimens was conducted. It can be observed from the results of the experimental study that the presence of fibers and shear reinforcement significantly improves the ultimate capacity and structural behavior of HPFRC members. Finally, the experimental results are discussed, and the shear capacity of HPFRC can be estimated by extending the code provisions stated in AFGC-Sétra 2013.

    DOI

  • Experimental and numerical investigation of static and fatigue behavior of mortar with blast furnace slag sand as fine aggregates in air and water

    Muhammad Aboubakar Farooq, Yasuhiko Sato, Toshiki Ayano, Kyoji Niitani

    Construction and Building Materials   143   429 - 443  2017.07

     View Summary

    The experimental and analytical study are attempted to clarify the static and fatigue behavior of mortar with blast furnace slag (BFS) sand as fine aggregates in compression in air and water. The cylindrical BFS mortar specimens were used for static and fatigue compression tests in air and water and results are compared with those of mortar using crushed sand (CS). The fatigue load was applied in the form of sine signal with a constant amplitude and the frequency of 5 Hz. The stress level is varied from 60%, 70% and 80% of the uniaxial compressive strength. The experimental results disclose that BFS mortar exhibits more fatigue life compared to CS mortar in air, while it is similar in water. Thereafter, the stress-strain relationships for each mortar under monotonic loading are formulated. Moreover, a simplified fatigue model for the assessment of plastic strain, total strain and fracture parameter at different number of loading cycles and for prediction of fatigue life is also proposed.

    DOI

  • Mechanical properties of concrete with blast furnace slag fine aggregates subjected to freeze-thaw cycles

    Muhammad Aboubakar Farooq, Kyoko Takeda, Yasuhiko Sato, Kyoji Niitani

    High Tech Concrete: Where Technology and Engineering Meet - Proceedings of the 2017 fib Symposium     65 - 72  2017

     View Summary

    This study presents the experimental investigation carried out to evaluate the performance of non air-entrained concrete with blast furnace slag (BFS) sand as full amount of fine aggregates under freeze thaw cycles in comparison with conventional air-entrained normal concrete. Cuboidal specimens were used for freeze-thaw test. The concrete specimens were subjected to freeze-thaw cycles (FTC) in 3% NaCl solution at the age of about 4 months. The duration of each freeze-thaw cycle was 8 h with temperature variation between +20 °C and -25 °C. The strain variation during each FTC was recorded using strain gauges attached to the concrete surface and change of relative dynamic modulus of elasticity was measured at certain number of FTC using ultrasonic pulse velocity method. The damage progress is discussed based on plastic tensile strain accumulated during freeze-thaw cycles. A particular number of specimens were taken out from freeze-thaw chamber after 50, 125 and 225 FTC. Thereafter, the static compressive strength tests were performed to determine the change in mechanical properties of concrete with blast furnace slag fine aggregates compared with normal concrete at different number of FTC. BFS concrete showed more compressive strength and Young's modulus for same FTC number compared to normal concrete, however, the rate of reduction of mechanical properties of air-entrained normal concrete is slightly slow.

    DOI

  • Structural performance assessment of bridge's girder using image measurement system and finite element analysis

    Wanakorn Prayoonwet, Tidarut Jirawattanasomkul, Yasuhiko Sato

    High Tech Concrete: Where Technology and Engineering Meet - Proceedings of the 2017 fib Symposium     1699 - 1706  2017

     View Summary

    This paper aimed to assess structural performance of superstructures of typical RC bridge in Thailand. The static load test was performed to measure both horizontal and vertical displacement in Reinforced Concrete (RC) girder using Image Measurement System (IMS). The RC girder's stiffness obtained from the IMS results is compared with that obtained from 3D Linear Finite Element Method. The stiffness from IMS is smaller than that from 3D FEM, indicating deterioration of RC girder. Besides, to predict the failure mode and capacity of RC girder, 2D Non-linear Finite Element Method. It was founded that the RC girder occurred shear and anchorage failure. In this paper, furthermore, the Load and Resistance Factor Rating (LRFR) is conducted to evaluate the performance of the bridge which has been designed by old LRFD specification. The results show that the moment rating factor and the shear rating factor for the designed load rating is equal to 1.20 and 1.01, respectively. From LRFR, the bridge still has sufficient capacity to carry both the AASHTO LRFD-design live load HL-93 and the AASHTO legal loads.

    DOI

  • Modeling of bond deterioration between steel bar and concrete subjected to freeze-thaw action

    Takeru Kanazawa, Yasuhiko Sato, Tomomasa Mikawa

    Journal of Advanced Concrete Technology   15 ( 8 ) 397 - 406  2017

     View Summary

    This study presents a new bond model based on the deterioration mechanisms observed during uniaxial tensile tests of reinforced concrete prismatic specimens subjected to freeze-thaw cycles. The test results demonstrated that the bond stress reduced, even though the specimens were exposed only to temperature fluctuation without the damage in concrete cover. The proposed model considers the bond deterioration mechanism caused by the temperature fluctuation in addition to the damage in concrete cover. Finally, the proposed model shows good agreement with the test results regardless of the dominant deterioration mechanism.

    DOI

  • Basic examination on assessing mechanical properties of concrete that has suffered combined deterioration from fatigue and frost damage

    Hiroshi Hayashida, Yasuhiko Sato, Tamon Ueda

    International Conference on Durability of Concrete Structures, ICDCS 2016     186 - 193  2016

     View Summary

    An examination including an evaluation of mechanical properties of concrete that had suffered combined deterioration from fatigue and frost damage was done using cylindrical specimens. The order of deterioration and degree of deterioration of the specimens were used as variables. The examination clarified that certain mechanical properties of concrete that had undergone combined deterioration were able to be evaluated by measuring the propagation speed of ultrasonic waves. The decrease in the elastic modulus and the ultrasonic velocity that accompanies the increase in the number of freeze-thaw cycles was smaller in the specimens that experienced fatigue first and then frost damage than in the specimens that experienced frost damage only. The values for mechanical properties (e.g., compressive strength, elastic modulus, and shrinkage strain) of the specimen that experienced frost damage first and then fatigue had already greatly decreased after the application of freeze- thaw cycles. Therefore, the decrease in the mechanical properties was small even with increases in the number of loading cycles. The decrease in the fatigue life of the specimen in the fatigue test was proportional to the deterioration from the preceding frost damage.

    DOI

  • Mechanical properties of oven-dried mortar exposed to high temperature considering different raw material

    Onnicha Rongviriyapanich, Yasuhiko Sato, Withit Pansuk

    Key Engineering Materials   711   504 - 510  2016

     View Summary

    Concrete structures can be deteriorated in extreme service conditions especially for fire incidents. For the evaluation of the post-fire performance, analytical methods are very powerful and useful. However, widely applicable mechanical models of fire-damaged material have not yet been proposed. To develop such models, the scale of control volume considering strength, stiffness and deformability is one of important factors. This paper presents an experimental study in which visual observations and mechanical properties of oven-dried mortar after exposed to the fire curves of ISO 834 and ASTM E119 for 90 minutes and to be left to cool down in air were conducted. Mortars were made from two different types of fine aggregate and cement. Experimental results indicate that the raw material made mortar is a prominent factor to introduce the different fire damage characteristics. Meanwhile, the mechanical properties of mortar in fire problem are strongly related to temperature that mortars were experienced to.

    DOI

  • Effect of concrete strength and amount of polyurea resin on concrete - Strand sheet bond

    M. Arazoe, A. Kobayashi, Y. Takahashi, Y. Sato

    Proceedings of the 8th International Conference on Fibre-Reinforced Polymer (FRP) Composites in Civil Engineering, CICE 2016     79 - 84  2016

     View Summary

    Bond performance of RC strengthened with polyurea resin and strand sheet depends on the concrete strength and the amount of polyurea resin. The present experimental study was undertaken in order to confirm the effect of above factors in the bond behaviour of concrete - strand sheet with a layer of polyurea resin by means of one side pull-out bond test method. Consequently, the specimen of the low strength concrete showed lower ultimate bond strength than that of the normal strength concrete at the same amount of polyurea resin regardless of presence or absence of the polyurea resin. However, the specimens with polyurea resin showed far higher ultimate strength than that of the specimens without polyurea resin regardless of the concrete strength. Furthermore, the bond strength was almost the same in the range of polyurea resin coating amount of 0.5-3kg/m2.

  • Modeling flexural behavior of RC beams strengthened with FRP by using RBSM

    Yasuhiko Sato, Khalid Farah

    Life-Cycle of Structural Systems: Design, Assessment, Maintenance and Management - Proceedings of the 4th International Symposium on Life-Cycle Civil Engineering, IALCCE 2014     1290 - 1297  2015

     View Summary

    The fiber-reinforced polymers (FRP) were used over the past years to strength the reinforced concrete (RC) beams and slabs by attaching it to their tension face. Despite considerable research over the last decade, reliable model to simulate the performance of strengthened beams still need more research. In this paper, a nonlinear numerical analysis code based on the rigid body spring model (RBSM) was extended to simulate the behavior of (RC) beams strengthened with externally bonded (FRP). The code supports the nonlinear constitutive laws for the different materials and nonlinear bond stress-slip relationships for steel - concrete and FRP-concrete interfaces. Previous experimental programs were used to validate the the model and confirm its ability to simulate the experimental observations. In all cases, very good agreement between the analytical and the experimental observations is obtained in terms of deflections, strains, internal forces, and failure mode, showing the capabilities of the model to evaluate the efficiency of proposed strengthening solutions.

    DOI

  • Modeling of physico-chemical property and mechanical characteristics of meso-scale mortar deteriorated by Ca leaching

    T. Miura, Y. Sato, H. Nakamura

    Life-Cycle of Structural Systems: Design, Assessment, Maintenance and Management - Proceedings of the 4th International Symposium on Life-Cycle Civil Engineering, IALCCE 2014     1678 - 1685  2015

     View Summary

    The purpose of this study is to grasp the change in mechanical behavior of meso-scale mortar specimens damaged by Ca leaching. Particularly, thin mortar specimens were immersed in demineralized water and NaCl solution for 0, 56, 112 and 168 days. After immersion tests, three points bending tests and double direct shear tests were carried out in order to determine elastic modulus, tensile strength, fracture energy and tensile softening curve from load displacement curves using back analysis and shear strength. In addition, chemical analysis was conducted so as to clarify how amount of calcium hydroxide and C-S-H and in the porosity quantitatively. Consequently, it was found that the change in mechanical behavior was strongly related to the change in the amount of cement hydrate and porosity. Furthermore, mechanical models that can consider the change in porosity were constructed and were evaluated adequacy itself.

    DOI

  • Strengthening effect of externally bonded CFRP sheets on pretensioned PC beams with ruptured strands in flexure

    K. Matsumoto, T. T.D. Nguyen, J. Niwa, A. Iwasaki, Y. Sato, T. Tsutsumi

    Life-Cycle of Structural Systems: Design, Assessment, Maintenance and Management - Proceedings of the 4th International Symposium on Life-Cycle Civil Engineering, IALCCE 2014     1283 - 1289  2015

     View Summary

    This paper presents the flexural strengthening effect of CFRP sheets on prestressed concrete (PC) beams having strands ruptured at the midspan. The increase in the number of sheets resulted in the reduction of tensile stress of the remaining prestressing strands. However, the increase in the number of sheets with insufficient sheet lengths did not provide a higher flexural strength because of the debonding from the sheet ends. The increase in the sheet lengths not only prevented the latter failure but also significantly improved the beam stiffness. More importantly, the debonding of the sheets was avoided by wrapping the transverse sheets for the whole beam span.

    DOI

  • Bond behaviors of RC strengthened with polyurea resin and CF sheet at high temperature

    M. Arazoe, T. Arai, S. Yamanobe, A. Kobayashi, Y. Sato

    Life-Cycle of Structural Systems: Design, Assessment, Maintenance and Management - Proceedings of the 4th International Symposium on Life-Cycle Civil Engineering, IALCCE 2014     1305 - 1312  2015

     View Summary

    Previously, beam bending tests had been conducted on strengthened RC beams with polyurea resin layer, which has low elastic modulus and high elongation, between the CFRP strand sheet (strand sheet for short) and concrete surface. It was found out that polyurea resin layer improves the bonding ability between the strand sheet and concrete surface. In this study, in order to examine the bonding ability of strand sheets with polyurea resin layer, a series of bonding test was carried out. Especially to verify the applicability of this method at elevated temperature for structure such as a chimney, bonding test at different temperature were selected. As a result, it was found out that bonding strength with polyurea resin was about 2.8 times more than that without polyurea resin at room temperature. Furthermore, it was found out that sufficient bonding performance can be achieved even at high temperature.

    DOI

  • Meso-Scale Analysis of the Mechanical Properties of Chemically-Deteriorated Mortar

    Y. Sato, T. Miura, H. Nakamura

    CONCREEP 2015: Mechanics and Physics of Creep, Shrinkage, and Durability of Concrete and Concrete Structures - Proceedings of the 10th International Conference on Mechanics and Physics of Creep, Shrinkage, and Durability of Concrete and Concrete Structures     1251 - 1258  2015

     View Summary

    How volume change of the cement hydrates affects mechanical characteristics of mortar after calcium leaching are discussed and prediction equations for elastic modulus, tensile strength, fracture energy and shear strength are proposed. Furthermore an analysis of mass transfer with chemical reaction based on a finite volume method is developed and is coupled with a mechanical analysis based on the RBSM. The validity of the coupled analytical method is discussed.

    DOI

  • Bond Deterioration Mechanism and Its Modeling for Reinforced Concrete Subjected to Freezing-Thawing Action

    T. Kanazawa, Y. Sato

    CONCREEP 2015: Mechanics and Physics of Creep, Shrinkage, and Durability of Concrete and Concrete Structures - Proceedings of the 10th International Conference on Mechanics and Physics of Creep, Shrinkage, and Durability of Concrete and Concrete Structures     1245 - 1250  2015

     View Summary

    A new bond model for reinforced concrete members considering material deterioration induced by freezing-thawing action has been developed. The developed model with the extensive applicability from non-damaged to severely damaged members can reasonably describe deterioration mechanism between steel bar and concrete.

    DOI

  • Analytical investigation on shear failure mechanism of RC T-beams with stirrups

    Takuro Nakamura, Yasuhiko Sato

    Concrete - Innovation and Design: fib Symposium Proceedings     53 - 54  2015

     View Summary

    Reinforced concrete T-beam is widely used in civil engineering structures and buildings. However, the evaluation method based on the shear resistance mechanism considering the effects of the top fange area has not been established in current structural design codes. The purpose of this study is to clarify the shear failure mechanism of RC T-beams with stirrups. The shear failure behaviours of the RC T-beams were investigated numerically with a three-dimensional nonlinear finite element method in which the width of the top flange, shear reinforcement ratio were varied. As a result, increasing in flange width of T-beam gives higher shear capacity with nonlinear relationship. The principal strain distribution and stirrups strain development of T-beams were different from the rectangular beam. In T-beams, the average shear stresses of web area in top flange were almost the same at the ultimate state, regardless of the flange width. In addition, the effect of shear reinforcement with respect to the increase of the average shear stress in fange area was not observed. The RC T-beam has a unique shear failure mechanism which is caused by T-shape cross-section and the horizontal crack.

  • Evaluation of structural properties of the freeze-thaw-damaged RC beam members by nonlinear finite-element analysis

    Hiroshi Hayashida, Yasuhiko Sato, Tamon Ueda

    Proceedings of the 4th International Conference on the Durability of Concrete Structures, ICDCS 2014     45 - 51  2014

     View Summary

    On RC beam members damaged by freeze-thaw cycles, the authors performed nonlinear finite-element analysis using distributed reinforcement and smeared cracking models, toward evaluating the structural properties of such RC beams. We then compared the analysis results to test results. The comparison found that the accuracy of analysis depends on the severity of concrete deterioration. It was clarified that the test values do not agree with the analysis values for RC beams that experience shear rigidity reduction from freezing damage to the compressive area or for RC beams that experience decreased rebar-concrete bonding strength from freezing damage to the tensile area. It was also clarified that the analysis may enable the evaluation of the rigidity to yield the failure mode and the maximum load for RC beams that have experienced no major decreases in shear rigidity and bonding strength. © 2014 4th International Conference on the Durability of Concrete Structures.

    DOI

  • Bonding and flexural behaviors of rc members with CFRP strand sheets - Polyurea soft layer system

    Masaki Arazoe, Akira Kobayashi, Yoshihiro Takahashi, Yasuhiko Sato

    Proceedings of the 7th International Conference on FRP Composites in Civil Engineering, CICE 2014    2014

     View Summary

    A strengthened method using CFRP strand sheets, which consist of bunch of hardened continuous fiber strands, and polyurea resin (shortly polyurea) with low elastic modulus have been newly developed by authors. In the method, layer of polyurea is inserted between concrete surface and FRP with the aim of improving bonding ability of the strand sheet. In this study, two kinds of test, bonding test and flexural test, were performed to clarify those effects of the polyurea soft layer on bonding ability of the strand sheet. To clarify the influence affected by temperature, bonding tests were carried out at two different temperatures, -20°C and 23°C. It was proved that inserting a polyurea soft layer was effective for improving bonding ability between the strand sheet and concrete surface at low temperatures and room temperatures, and flexural capacity of concrete beams strengthened with the strand sheet.

  • 鉄筋腐食したコンクリート構造物の構造・耐久性能評価の体系化研究委員会

    MISHIMA TETSUYA, YAMAMOTO TAKASHI, OSHITA HIDEKI, KANAKUBO TOSHIYUKI, KUNIEDA MINORU, SATO YASUHIKO

    コンクリート工学年次論文集(CD-ROM)   35   ROMBUNNO.9002  2013.06

    J-GLOBAL

  • Modeling of Tension Stiffening Behavior in FRP-Strengthened RC Members Based on Rigid Body Spring Networks

    Jian Guo Dai, Tamon Ueda, Yasuhiko Sato, Kohei Nagai

    Computer-Aided Civil and Infrastructure Engineering   27 ( 6 ) 406 - 418  2012.07

     View Summary

    Allowing for the tension stiffening effects resulting from the bond between steel reinforcement and surrounding concrete leads to effective deformation analysis of reinforced concrete (RC) members when using a nonlinear finite element analysis modeled on the smeared crack concept. Nowadays, externally bonded fiber reinforced polymer (FRP) composites are widely used for strengthening existing RC structures. However, it remains unclear to what extent the tension stiffening of postcracking concrete is quantitatively influenced by the addition of FRP composites, as a result of the bond between the FRP and the concrete substrate. This article presents a discrete model, which is based on rigid body spring networks (RBSN), for investigating the tension stiffening behavior of concrete in FRP-strengthened RC tensile members. A two-parameter fracture energy-based model was deployed to represent the bond-slip behavior of the FRP-to-concrete interface. The reliability of the RBSN model was verified through comparisons with previous test results. Further parametric analysis indicates that the tension stiffening of concrete is hardly influenced by the addition of FRP composites before the yield of steel reinforcement has occurred although concrete crack patterns and crack widths may be influenced by the bond-slip behavior of the FRP-to-concrete interface. © 2011 Computer-Aided Civil and Infrastructure Engineering.

    DOI

  • Failure behavior of RC beams in relation to the extent and location of frost damage

    Hiroshi Hayashida, Yasuhiko Sato, Tamon Ueda

    Proceedings of the 3rd International Conference on the Durability of Concrete Structures, ICDCS 2012    2012

     View Summary

    Loading tests were performed on RC beams with the depth and location of frost damage as variables. The results showed which side of the beams was damaged by frost (i.e., the compression side or the tension side) and indicated that the maximum bearing capacity, deformation properties and failure mode varied significantly with the extent of the deterioration. Specifically, with respect to deterioration on the compression side, deeper frost damage resulted in impaired performance in terms of rigidity and displacement under the maximum load, and the failure mode was more likely to shift to that of diagonal compression. For deterioration on the tension side, it was found that shallower frost damage corresponded to better deformation performance, with the failure mode shifting to a tied arch mechanism due to bond deterioration. However, deeper frost damage caused brittle diagonal tensile failure and may have resulted in reduced deformation performance.

  • Bonding characteristics and strengthening effect of strand sheet with soft layer

    Masaki Arazoe, Yasuhiko Sato, Yoshihiro Takahashi, Akira Kobayashi

    Proceedings of the 6th International Conference on FRP Composites in Civil Engineering, CICE 2012    2012

     View Summary

    We have developed advanced CFRP strand sheets which consist of bunch of hardened continuous fiber strands. It is assumed that the bonding ability of the strand sheet can be improved by putting a soft layer in between the strand sheet and concrete surface. In this study, the polyurethane resin was used to form a soft layer. In order to clarify the effectiveness of the polyurethane soft layer on the bonding ability of the strand sheet, bonding tests and beam bending tests in which the strand sheet was attached on concrete surface using epoxy resin with or without the polyurethane soft layer were carried out. As a result, it was found out that the polyurethane soft layer was effective for improving bonding ability between the strand sheet and concrete surface and flexural capacity of concrete beams strengthened with the strand sheet.

  • Uniaxial Tension Behavior of Reinforced Concrete Members Strengthened with Carbon Fiber Sheets

    Khalid Farah, Yasuhiko Sato

    JOURNAL OF COMPOSITES FOR CONSTRUCTION   15 ( 2 ) 215 - 228  2011.03

     View Summary

    A two-dimensional (2D) nonlinear numerical analysis code by using the rigid body spring method (RBSM) was developed by the writers at Hokkaido University to simulate the behavior of reinforced concrete (RC) members strengthened with fiber-reinforced polymer (FRP) sheets. The code supports the nonlinear constitutive laws for the different materials and nonlinear bond stress-slip relationships for steel-concrete and FRP sheet-concrete interfaces. This study uses the aforementioned code to examine the uniaxial tension behavior of RC members strengthened with carbon fiber sheets (CFS). Experimental results are compared with relevant numerical outputs to validate the model and confirm its ability to simulate the experimental observations. This study also assesses the influence of the amount of CFS strengthening on the tension-stiffening behavior of strengthened members. Finally, this research also suggests new analytical expressions for the average stress-strain relationships of concrete and steel in tension in the presence of stiffening contributions from internal steel reinforcement bars and externally bonded CFS reinforcement. DOI: 10.1061/(ASCE)CC.1943-5614.0000175. (C) 2011 American Society of Civil Engineers.

    DOI

  • Evaluation of tensile behaviour of mortar immersed in a NACL solution

    Taito Miura, Yasuhiko Sato

    Advances in Concrete Structural Durability - Proceedings of the 2nd International Conference on Durability of Concrete Structures, ICDCS 2010     147 - 156  2010

     View Summary

    The purpose of the present study was to determine the change in tensile behavior of a meso-scalc mortar specimen immersed in a solution of NaCl. In particular, mortar specimcns were immersed in a NaCl solution for 2 months, and then three-point bending tests and chemical analyses were conducted to determine the influence of the cement hydrate (CH and CSH) concentration on the tension-softening behavior of the material. To this end, tension- softening curves were obtained from load-displacement curves via a back analysis. Wc found that tensile strength and fracture energy were reduced as the concentration of CH decreased. Furthermore, the tensile-softening model for the deteriorated mortar was proposed. ©2010 by Hokkaido University Press All rights reserved.

  • Meso-scale analysis of mortar deteriorated by acid

    Y. Oiwa, Y. Sato, T. Miura

    Concrete under Severe Conditions: Environment and Loading - Proceedings of the 6th International Conference on Concrete under Severe Conditions, CONSEC'10   1   569 - 575  2010

     View Summary

    Concrete would be deteriorated by various factors in severe environment. Chemical erosion of concrete in acidity environment is one of important deterioration mechanism. It is not clarified, however, how chemical characteristic change affects mechanical characteristics. Meanwhile, a meso-scale approach in which both aggregate and mortar can be modeled is on the verge of becoming possible to apply to such durability problems. In this paper, the relationships between chemical characteristic change (amount of CH and CSH) and mechanical characteristic change are examined experimentally and then the mechanical behavior is simulated by Rigid Body Spring Method which is a typical meso-scale analysis. In particular, meso-scale constitutive laws are obtained from the bending tests of deteriorated mortar specimens after immersion test. Finally the applicability and availability of the analysis with the developed constitutive laws are discussed based on comparison with experimental. © 2010 Taylor & Francis Group, London.

  • Basic characteristics of FRP strand sheets and flexural behavior of RC beams strengthened with FRP strand sheets

    A. Kobayashi, Y. Sato, Y. Takahashi

    APFIS 2009 - Asia-Pacific Conference on FRP in Structures     93 - 98  2009

     View Summary

    When attaching continuous fiber sheets on concrete members on site, bonding defection of the continuous fiber sheets likely happens. FRP strips could solve the problem associated with the continuous fiber sheets, though they also have demerit due to less adhesion property caused by small adhesive area. To solve these problems, we have developed advanced FRP strand sheets which consist of bunch of individually hardened continuous fiber strands. The FRP strand sheets can be easily attached on the surface of concrete members with a single adhesive. Thus, the advanced strand sheets assure better construction quality and enable to cut down on application time and/or costs. Series of tensile, lap splice, and bonding tests were conducted in order to evaluate the material characteristics of CFRP strand sheets. Bending test of RC (Reinforced Concrete) beams was also conducted to evaluate strengthening effect of the CFRP strand sheets. In each test, specimens strengthened with CFRP strand sheets, with ordinal carbon fiber sheets or with CFRP strips were prepared. In the bending test, it was observed that both bending stiffness and capacity of RC beams were increased by strengthening with CFRP strand sheets. It was also observed that ultimate load, which was determined by delamination of strengthening material; of specimen strengthened with CFRP strand sheets was the greatest among all the specimens. Furthermore, the influence of concrete strength and depth of cover concrete on flexural strengthening effect of the FRP strand sheets were investigated.

  • Mesoscale simulation of influence of frost damage on mechanical properties of concrete

    Tamon Ueda, Muttaqin Hasan, Kohei Nagai, Yasuhiko Sato, Licheng Wang

    Journal of Materials in Civil Engineering   21 ( 6 ) 244 - 252  2009

     View Summary

    Mesoscale constitutive models of frost-damaged concrete are developed in this study through numerical simulation using a two-dimensional rigid body spring model (RBSM). The aim of the simulation is to predict the macrobehavior of frost-damaged concrete subjected to mechanical loading. The models also clarify the difference in failure behavior of concrete with and without frost damage. Zero strength elements and the concept of mesoscale plastic tensile strain are introduced into the normal RBSM springs to consider the experimentally observed cracking and plastic deformation caused by frost damage. The difference in the effect of frost damage on compression and tension behavior as found in the experiments is clearly predicted. Finally, analysis of a notched beam subjected to bending after different degrees of frost damage is carried out. The resulting load-deflection curves agree well with those obtained in the experiments. These good correlations confirm the applicability of the mesoscale model for predicting the macrobehavior of frost-damaged concrete. © ASCE 2009.

    DOI

  • Mesoscopic simulation and damage estimation of mortar under high-stress fatigue loading

    K. Matsumoto, Y. Sato, T. Ueda

    Creep, Shrinkage and Durability Mechanics of Concrete and Concrete Structures - Proceedings of the 8th Int. Conference on Creep, Shrinkage and Durability Mechanics of Concrete and Concrete Structures   2   1171 - 1177  2009

     View Summary

    Analytical system for mortar failure under time-dependent loading was extended to high strain rate range by improving the time-dependent constitutive model of Rigid Body Spring Model. Using the model, experimental results of mortar specimens subjected to high strain rate loading and fatigue loadings were well simulated. Furthermore, damage accumulation of mortar under fatigue loading was explained in terms of the degradation in residual strength. It was confirmed analytically that damage accumulation of mortar is not proportional to number of loading cycles but suddenly increase near the failure point.© 2009 Taylor & Francis Group.

  • Mesoscopic analysis of mortar under high-stress creep and low-cycle fatigue loading

    Koji Matsumoto, Yasuhiko Sato, Tamon Ueda, Licheng Wang

    Journal of Advanced Concrete Technology   6 ( 2 ) 337 - 352  2008.06

     View Summary

    Mesoscopic analyses of mortar failure under high-stress creep and low-cycle fatigue loading are presented using a newly developed time-dependent constitutive model for Rigid Body Spring Model, which is a discrete analysis method. The failure process over time was successfully expressed by adopting a four-component combined mechanical model as the time-dependent model of connected springs, and by developing a new method for determining the failure state for load-controlled analysis. The numerical model provides reasonable results not only for the stress-strain characteristics under cyclic loading but also for the inapplicability of Miner's law under varying stress levels. The mechanism of the time-dependent failure of mortar was clarified by investigating the local stress-strain behaviors. © 2008 Japan Concrete Institute.

    DOI

  • Stress-Strain relationship of frost-damaged concrete subjected to fatigue loading

    Muttaqin Hasan, Tamon Ueda, Yasuhiko Sato

    Journal of Materials in Civil Engineering   20 ( 1 ) 37 - 45  2008.01

     View Summary

    This study attempted to develop a model for the stress-strain relationship in compression of frost-damaged concrete subjected to fatigue loading. Concrete specimens were prepared and exposed to freeze-thaw cycles followed by application of static and fatigue loading. The strains induced during the freeze-thaw test were carefully measured as well as during a mechanical loading test. It was found that the static strength and the fatigue life of concrete decreases as increasing irreversible tensile strain was induced by frost action. A stress-strain model for frost-damaged concrete under application of static and fatigue loading based on the degradation of initial stiffness caused by frost damage was presented. The degradation of initial stiffness for damaged concrete was empirically formulated as a function of remaining expansion caused by freeze-thaw cycles. The plastic strain under the application of mechanical static and fatigue loading for frost-damaged concrete is higher than that for original concrete. Therefore, plastic strain for damaged concrete was formulated as not only the function of strain level under mechanical loading, but also the function of irreversible strain caused by frost action. The unloading and reloading stiffness factors were introduced to explain the change of stiffness as increasing the number of loading cycles by considering the effect of the degree of frost damage. © 2008 ASCE.

    DOI

  • Shear mechanism of reinforced concrete T-Beams with stirrups

    Withit Pansuk, Yasuhiko Sato

    Journal of Advanced Concrete Technology   5 ( 3 ) 395 - 408  2007.10

     View Summary

    As is well known, in the current design code, the shear strength of beams can be calculated based on the modified truss theory, which cannot take into account the effects of the top flange area of T-beams. Reported experimental data show that the top flange has an effect on the shear capacity of T-beams with shear reinforcement. To predict the shear capacity of T-beams more precisely, the effect of the concrete top flange area on the shear resisting mechanism must be clarified. Comparison of test results for rectangular and T-beams yielded insights into the shear resisting mechanism of T-beams. Verification and clarification of the shear resisting mechanism of T-beams were performed based on the 3D nonlinear finite element code (CAMUI). Finally, a simplified method for determining the failure criteria for shear of RC T-beams is proposed. Copyright © 2007 Japan Concrete Institute.

    DOI

  • Tension stiffening of high performance fiber reinforced concrete

    R. Shionaga, J. C. Walraven, J. A. Den Uijl, Y. Sato

    Concrete Structures - Stimulators of Development, Proceedings of the fib Symposium Dubrovnik 2007     259 - 266  2007

     View Summary

    High Performance Fiber Reinforced Concrete (HPFRC), which has a high compressive strength of about 130 N/mm2 and a high tensile ductility by the addition of short steel fibers, was used in this study. Axial tensile tests on reinforced HPFRC members were conducted in order to investigate the influence of fibers on tension stiffening. Therefore the fiber content and the dimensions of the fibers (aspect ratio) were varied in the HPFRC mixture . The average concrete stresses, which were derived from the test results after correction for the initial shrinkage strain, showed that an increase e of the fiber content and a larger aspect ratio lead to a higher tension stiffening. Moreover, a simplified equation to determine the tension stiffening in HPFRC was proposed on the basis of the axial tensile test results.

  • Bonding characteristics of fiber-reinforced polymer sheet-concrete interfaces under dowel load

    Jianguo Dai, Tamon Ueda, Yasuhiko Sato

    Journal of Composites for Construction   11 ( 2 ) 138 - 148  2007

     View Summary

    Based on a series of experimental tests on notched concrete beams externally bonded with unidirectional fiber-reinforced polymer (FRP) sheets, this paper investigates the bond characteristics of FRP sheet-concrete interfaces under dowel load, which acts vertically on the FRP sheet and leads to a mix-mode interface peeling. The peeling properties of FRP sheet-concrete interfaces under the dowel load are evaluated in terms of their interface dowel load-carrying capacity, critical interface peeling angle, and interface peeling fracture energy. Experimental parameters include strength of concrete substrate, tension stiffness of FRP sheets, properties of bonding adhesives, concrete surface treatment methods, and length of precrack set between the FRP sheet and concrete substrate. Analytical models clarifying the relationships among the interface dowel load-carrying capacity, the interface peeling angle, and the interface peeling fracture energy are built up and also verified by test results. Further, this paper shows how to use the interface peeling fracture energy calibrated from the present dowel tests for the practical design of spalling prevention, which is now becoming a popular application of FRP sheets for the maintenance and repair of existing concrete structures in Japan. © 2007 ASCE.

    DOI

  • FE analysis of ultra high performance fiber reinforced concrete

    W. Pansuk, Y. Sato, R. Shionaga, J. C. Walraven

    Computational Modelling of Concrete Structures - Proceedings of EURO-C 2006     397 - 404  2006

     View Summary

    FEM in combination with an appropriate material model may serve as a suitable tool to analyze the structural performance of UHPFRC. Some reported constitutive models considering the effect of steel fibers are installed into the 3D FE program. The comparisons between the numerical and the experimental results are performed to confirm the applicability of the proposed models from the view point of structural performance. Moreover, a sensibility analysis is conducted to evaluate the effect of the material parameters on shear behavior of beams with UHPFRC. A new concept for a combination of the constitutive models in FEM is introduced in the present study. In the analysis, the constitutive laws are varied for different fiber directions in a numerical specimen following the phenomenal fact that orientation number differs for different considering directions in 3D space. Finally, the advantage of simulation by the proposed technique compared with current FE methods and test results are demonstrated on the structural level. © 2006 Taylor & Francis Group.

  • Unified analytical approaches for determining shear bond characteristics of FRP-concrete interfaces through pullout tests

    Jianguo Dai, Tamon Ueda, Yasuhiko Sato

    Journal of Advanced Concrete Technology   4 ( 1 ) 133 - 145  2006

     View Summary

    The pullout test is a conventional test method for calibrating interfacial shear bond characteristics of Fiber Reinforced Polymer (FRP)-concrete interfaces. However, due to the small bending stiffness of FRP sheets/strips and the highly non-linear interface fracturing mechanism, a well-recognized analytical approach to the accurate interpretation of the pullout test results remains to be achieved despite extensive studies particularly when the aim is to calibrate a local bond stress-slip model, which is necessary for developing bond strength and anchorage length models avoiding the use of empirical formulations. This paper introduces a newly developed non-linear bond stress-slip model for analyzing full-range strain distributions in FRP and shear bond stress distributions in the interface bond layer during pullout tests, along with a new anchorage length model and bond strength model that were developed accordingly. Compared with other existing bond models, the bond model described here has two advantages besides its simplicity: (1) it incorporates the most important interface parameter, the so-called interfacial fracture energy, in all analytical processes and links it successfully with all other important bond parameters; (2) it is a general and unified approach that allows for the first time consideration of the effects of the adhesive bond layer in non-linear analysis of FRP-concrete interfaces. Further, a unified bond stress versus slip expression is formulated to show the differences in local bond stress-slip relationships at the loaded and free ends in pullout tests, so that the effects of the bond length used in a pullout test on the calibration of the interfacial bond stress-slip model can be clarified. The reliability of all proposed models is verified through a comprehensive comparison of the experimental and analytical results. Copyright © 2006 Japan Concrete Institute.

    DOI

  • Static and fatigue bond characteristics of interfaces between CFRP sheets and frost damage experienced concrete

    Jianguo Dai, Yuki Saito, Tamon Ueda, Yasuhiko Sato

    American Concrete Institute, ACI Special Publication   SP-230   1515 - 1530  2005.10

     View Summary

    Both short and long-term performances of repaired or strengthened concrete structures using external FRP bonding are greatly affected by states of bonding substrates, which are covercrete and may have experienced various damages. One of them is frost damage in cold regions. This paper intends to investigate how the initial frost damages in concrete influence the static and fatigue bond performances of CFRP/concrete interfaces. Concrete specimens were exposed to freeze and thaw cycles before being bonded with CFRP sheets. The initial frost damage of concrete was controlled approximately at three different levels in terms of its relative dynamic modulus of elasticity, which was 100% (non frost damage), 85% and 70%, respectively. Test results showed that failure modes of CFRP/concrete bonded joints with initial frost damage in concrete were the delamination of covercrete. By contrast the joints without initial frost damage failed in a thin concrete layer as usual. Moreover, CFRP/concrete joints with and without initial frost damage showed different manners in their interface bonding strength and stiffness. If the initial frost damage existed in concrete substrate the effective bond length of CFRP/concrete joints was increased due to the decrease of the bonding stiffness and interfacial fracture energy. Fatigue testing results indicated that the linear slopes of S-N curves of CFRP/concrete bonded joints were not influenced by the initial frost damage. The initial frost damage did not shorten the fatigue life of CFRP/concrete joints if a same relative tensile stress level was kept in the FRP sheets, where the relative tensile stress level was defined as a ratio of the applied tensile force in FRP sheets for the fatigue tests to the maximum static pullout one achieved in each test series.

  • Development of the nonlinear bond stress-slip model of fiber reinforced plastics sheet-concrete interfaces with a simple method

    Jianguo Dai, Tamon Ueda, Yasuhiko Sato

    Journal of Composites for Construction   9 ( 1 ) 52 - 62  2005.01

     View Summary

    A new analytical method for defining the nonlinear bond stress-slip models of fiber reinforced plastics (FRP) sheet-concrete interfaces through pullout bond test is proposed. With this method, it is not necessary to attach many strain gauges on the FRP sheets for obtaining the strain distributions in FRP as well as the local bond stresses and slips. Instead, the local interfacial bond stress-slip models can be simply derived from the relationships between the pullout forces and loaded end slips. Based on a series of pullout tests, the bond stress-slip models of FRP sheet-concrete interfaces, in which different FRP stiffness, FRP materials (carbon FRP, aramid FRP, and glass FRP), and adhesives are used, have been derived. Only two parameters, the interfacial fracture energy and interfacial ductility index, which can take into account the effects of all interfacial components, are necessary in these models. Comparisons between analytical results and experimental ones show good accordance, indicating the reliability of the proposed method and the proposed bond stress-slip models.

    DOI

  • Mesoscopic simulation of failure of mortar and concrete by 3D RBSM

    Kohei Nagai, Yasuhiko Sato, Tamon Ueda

    Journal of Advanced Concrete Technology   3 ( 3 ) 385 - 402  2005

     View Summary

    Concrete is a heterogeneous material consisting of mortar and aggregate at the meso scale. Evaluation of the fracture process at this scale is useful to clarify the material characteristic of concrete. The authors have conducted meso scale analysis of concrete over a past few years by Rigid Body Spring Model (RBSM). In this study, three-dimensional analyses of mortar and concrete are carried out, which is necessary for the quantitative evaluation of concrete behavior especially in compression. Constitutive models at the meso scale are developed for the 3D RBSM analysis. Failure behaviors and strengths in compression and tension of mortar and concrete are predicted well by the analysis. In biaxial compression test of concrete, crack in normal direction to plane of specimen is simulated that cannot be presented by two-dimensional analysis. Copyright © 2005 Japan Concrete Institute.

    DOI

  • 3D nonlinear punching shear simulation of steel-concrete composite slab

    Ryosuke Takahashi, Yasuhiko Sato, Katsuyuki Konno, Tamon Ueda

    Journal of Advanced Concrete Technology   3 ( 2 ) 297 - 307  2005

     View Summary

    In this study, a model for the interface between a concrete slab and a steel plate in composite slabs with studs is developed through a bending test for composite beams. A smeared reinforcing stud model is also implemented to consider the shear-reinforcing effect of taller studs. 3D nonlinear finite element analysis using the model for the interface and the reinforcing stud model developed in this study is found to predict punching shear behavior of composite slabs. Copyright © 2005 Japan Concrete Institute.

    DOI

  • Diagonal tensile failure mechanism of reinforced concrete beams

    Yasuhiko Sato, Toshiya Tadokoro, Tamon Ueda

    Journal of Advanced Concrete Technology   2 ( 3 ) 327 - 341  2004.10

     View Summary

    The mechanism of diagonal tensile failure of RC beams without shear reinforcement, which is difficult to solve by means of experimental and analytical study, is investigated. The close relationship between the fracture modes and the transfer stress at shear cracks is clarified, and the experimental results are verified by the finite element method taking into consideration the influence of a splitting tensile crack and dowel action. In RC members without shear reinforcement, the width of a shear crack increases owing to the occurrence of a splitting tensile crack along the main bars. As a result, the transfer stress of a shear crack cannot be generated and the shear crack grows and propagates rapidly. This paper also puts forth that FE analysis, in which not only shear crack but also splitting tensile crack are modeled discretely, can predict the size effect on diagonal tensile failure strength of RC beams without shear reinforcement.

    DOI

  • Mesoscopic simulation of failure of mortar and concrete by 2D RBSM

    Kohei Nagai, Yasuhiko Sato, Tamon Ueda

    Journal of Advanced Concrete Technology   2 ( 3 ) 359 - 374  2004.10

     View Summary

    Concrete is a heterogeneous material consisting of mortar and aggregate at the meso level. Evaluation of the fracture process at this level is useful to clarify the material characteristic of concrete. However, the analytical approach at this level has not yet been sufficiently investigated. In this study, two-dimensional analyses of mortar and concrete are carried out using the Rigid Body Spring Model (RBSM). For the simulation of concrete, constitutive model at the meso scale are developed. Analysis simulates well the failure behavior and the compressive and tensile strength relationship of mortar and concrete under uniaxial and biaxial stress conditions. Localized compressive failure of concrete is also simulated qualitatively.

    DOI

  • Stress-strain model of concrete damaged by freezing and thawing cycles

    Muttaqin Hasan, Hidetoshi Okuyama, Yasuhiko Sato, Tamon Ueda

    Journal of Advanced Concrete Technology   2 ( 1 ) 89 - 99  2004.02

     View Summary

    This study investigates the dependence of the mechanical behavior of concrete, such as strength, stiffness, and deformation capacity on the damage caused by freezing and thawing cycles (FTC). A stress-strain model for concrete damaged by freezing and thawing prior to the application of mechanical loading was proposed based on plasticity and fracture of concrete elements. The FTC fracture parameter was introduced to explain the degradation in initial stiffness of concrete resulting from freezing and thawing damage. Based on experimental data, the FTC fracture parameter was empirically formulated as a function of plastic tensile strain caused by freezing and thawing with the assumption that the plastic strain was caused by the combined effects of FTC and mechanical loading damage. The stress-strain relationships obtained by the proposed model were compared with the experimental data.

    DOI

  • 1257 MODE I FRACTURE BEHAVIORS OF FRP-CONCRETE INTERFACES :

    DAI Jianguo, UEDA Tamon, HASAN Muttaqin, SATO Yasuhiko

    Journal of the Japan Society for Composite Materials   25 ( 1 ) 1577 - 1582  2003

     View Summary

    The Mode II interlaminar fracture tests of hybrid composites with non-woven carbon tissue (NWCT) were carried out using the end-notched-flexure (ENF) specimen. The hybrid composites were made by interleaving NWCT prepreg between CFRP layers. CFRP specimen [024] as well as hybird specimen [012/T/012] were prepared to compare the Model II interlaminar fracture tough-ness. Here, the symbol "/T/" means that NWCT prepreg is located at a 0/0 mid-plane of the hybrid specimen. Three kinds of interlaminar cracks which have different positions in the NWCT layer were introduced to the hybrid specimen. It was found that the NWCT layer has the short fiber bridging effect due to in-plane random short carbon fibers and increases the interlaminar fracture toughness of laminated composites. The fracture surfaces and side-sections of the hybird specimens were observed with an optical microscope and a scanning elelctron microscope, and the failure mechanism was discussed.

    DOI CiNii

  • Study on behavior in tension of reinforced concrete members strengthened by carbon fiber sheet

    Tamon Ueda, Ryuichi Yamaguchi, Kazuteru Shoji, Yasuhiko Sato

    Journal of Composites for Construction   6 ( 3 ) 168 - 174  2002.08

     View Summary

    This paper presents experimental results on the behavior in tension of reinforced concrete members strengthened with carbon fiber sheets (CFS). CFS reduced the crack spacing and brought about good crack width control as well as a significant change in the average bond stress and the average stress of steel reinforcing bars and concrete. The deterioration mechanism of the CFS bond properties near cracks was presented.

    DOI

  • New approach for usage of continuous fiber as non-metallic reinforcement of concrete

    Tamon Ueda, Yasuhiko Sato

    Structural Engineering International: Journal of the International Association for Bridge and Structural Engineering (IABSE)   12 ( 2 ) 111 - 116  2002

     View Summary

    Continuous fiber such as carbon fiber, aramid fiber and glass fiber, have been accepted as a substitute for conventional steel reinforcement because of its good characteristics: high strength, lightness, anti-corrosiveness, anti-magnetism and flexibility. At the same time continuous fibers also show some major drawbacks when compared with steel. This article introduces new directions for continuous fiber to overcome its drawbacks and to utilize its unused advantage. The new directions necessitate the development of new materials.

    DOI

  • The influence of compression softening to the shear strength of RC members

    Toshiya Tadokoro, Yasuhiko Sato, Tamon Ueda

    Transactions of the Japan Concrete Institute   23   391 - 398  2001

     View Summary

    Modeling of compression softening is essential to predict the ultimate behavior of RC members. In this study, constitutive laws of concrete under compression-tension state are extended according to the concept of the fracture energy and the influence of compression softening on ultimate behavior of RC members failing in shear compression mode was examined. It was found that the ultimate strength and deformation strongly depended on compression softening, namely compression fracture energy. It was also found that the analytical results agreed well with experimental ones, when compression fracture energy of 40 N/mm was used for normal concrete with compressive strength of 20 MPa.

  • Uniaxial tensile behavior of reinforced concrete elements strengthened by carbon fiber sheet

    Yasuhiko Sato, Kazuateru Shouji, Tamon Ueda, Yoshio Kakuta

    American Concrete Institute, ACI Special Publication   SP-188   697 - 710  1999.08

     View Summary

    The uniaxial tensile tests of Reinforced Concrete elements with Carbon fiber sheet (RCC) are conducted to clarify the basic mechanical characteristics which affect the tension stiffness of RCC. This paper mainly presents the difference between RCC and ordinary Reinforced Concrete member (RC) in the load carrying capacity, the average crack spacing, stress and/or strain distributions of steel, and the average stress - strain relationship of concrete. Crack spacing of RCC becomes smaller between 25% and 60% of that in RC as the amount of Carbon Fiber Sheet (CFS) increases. The strain distributions of steel in RCC before and after the yielding of steel differ from those in RC. The tension stiffness developed by the bond action of CFS increases as the amount of CFS increases but that of steel becomes less. With the steel and CFS contributions combined, the tension stiffness of concrete as a whole generally becomes greater than that in RC. There is, however, a case in which tension stiffness of concrete in RCC decreases more than that in RC, because the average bond stress of steel rapidly decreases after the yielding of steel.

  • Experimental study on bond strength of continuous carbon fiber sheet

    Tamon Ueda, Yasuhiko Sato, Yasuyuki Asano

    American Concrete Institute, ACI Special Publication   SP-188   407 - 416  1999.08

     View Summary

    An experimental study on bond strength of Continuous Fiber Sheet (CFS) was conducted. Based on the experimental results the bond strength and various factors are clarified. Bond strength does not increase with bond length for bond length longer than 100 mm. As CFS stiffness increases, the maximum local and average bond stresses at delamination increase and CFS strain gradient decreases. CFS with a narrower width has a bond strength greater than that with a wider width. Non-uniform loading decreases the bond strength, however anchor steel plate with tensioned bolt increases it due to the bond between steel plate and CFS and confmement from the bolt. From the observed bond stress in CFS, the equation to predict the maximum local bond stress was proposed.

  • Flexural strengthening of reinforced concrete beams with carbon fiber sheets

    Yoshihiro Takahashi, Chihiro Hata, Yasuhiko Sato, Tamon Ueda, Toshiya Maeda

    American Concrete Institute, ACI Special Publication   SP-188   711 - 724  1999.08

     View Summary

    The simple-supported concrete beams reinforced with aramid FRP (AFRP) rods and carbon FRP (CFRP) sheets were tested to failure using a symmetric two-point concentrated static loading system. AFRP rods were used instead of steel reinforcing bars, and CFRP sheets were epoxy bonded to the tension face of the concrete beams to enhance their flexural strength. Moreover, a 5-cm wide strip of CFRP sheet in some places were wrapped around the web (hereafter, called "U· jacket") after the CFRP sheets were bonded. The strain distributions on AFRP rods and CFRP sheets, and flexural behavior of the beams with AFRP rods and CFRP sheets were examined experimentally. The results showed that; 1) peeling of CFRP sheets occurred near the maximum flexural moment region, 2) ultimate load and deflection of the beam with U-jackets were higher, and 3) the U-jacket was a significant factor affecting the ductile behavior of beams with CFRP sheets.

  • Development of continuous fiber flexible reinforcement

    Tetsuya Sugiyama, Saki Tomita, Satoshi Kouzaki, Yasuhiko Sato, Tamon Ueda, Akira Kobayashi

    American Concrete Institute, ACI Special Publication   SP-188   13 - 22  1999.08

     View Summary

    The authors have developed a continuous fiber flexible reinforcement (CFFR) which has good workability and can be used as a reinforcement in concrete. It consists of a plastic tube containing continuous fiber bundles and resin. The salient feature of this new material is that it can be easily formed at the construction site. The authors have conducted a study of fabrication methods of the material and an evaluation of its mechanical properties. This paper introduces the material and fabrication methods, and details the tensile strength of a member formed from this material. A member bent into a U shape was subjected to a load test to examine its basic properties. As a result, it was found that even when the material was bent, the applied tensile load was transmitted through it. Also, the load-deflection characteristic of the material and the stress concentration due to bending were influenced by the wall thickness of the plastic tube.

  • Study on continuous fiber flexible reinforcement as shear reinforcement for concrete members

    Saki Tomita, Satoshi Kozaki, Yasuhiko Sato, Akira Kobayashi

    Transactions of the Japan Concrete Institute   21   235 - 240  1999

     View Summary

    This study shows how reducing the thickness of the tube enclosing continuous fiber flexible reinforcement (CFFR) and providing mechanical anchorage at the end of CFFR improve the shear capacity of a beam specimen. It is also clarified in this study that from tensile tests on U shaped specimen of CFFR the shear capacity in a concrete beam reinforced with CFFR is greatly influenced by the deformational characteristics of CFFR, i.e., a slippage at bent portion of fibers and deformation of tube covering the fibers.

  • Mechanical property of recycled concrete under lateral confinement

    Katsuyuki Konno, Yasuhiko Sato, Tamon Ueda, Masaaki Onaga

    Transactions of the Japan Concrete Institute   20   287 - 292  1998

     View Summary

    The aim of this study is to clarify the strength and the deformational ability of recycled concrete. It was clarified that the deformational behavior of recycled concrete filled steel tube (RCFT) was similar to that of normal concrete filled steel tube (CFT). It was shown that the stiffness of RCFT could be predicted approximately with consideration of the Young's modulus of recycled concrete which were lower than that of normal concrete. It was also shown that of the dilatancy in the elasto-plastic range, which is related to the Poisson's ratio, is important to predict the strength.

  • Experimental study on flexural behavior of aramid rods reinforced concrete beam strengthened with externally bonded carbon fiber sheet

    Yoshihiro Takahashi, Chihiro Hata, Toshiya Maeda, Yasuhiko Sato

    Transactions of the Japan Concrete Institute   20   97 - 104  1998

     View Summary

    Simple-supported concrete beams reinforced with aramid FRP (AFRP) rods and carbon FRP (CFRP) sheets were tested up to failure under a symmetric two-point load application. AFRP rods were used instead of steel reinforcing bars, and CFRP sheets were bonded on the tension face. Moreover, in one specimen, three 5-cm wide strips of CFRP sheeting were wrapped around the web (U-jacket) after the CFRP sheets were bonded. The results showed that; 1) both the ultimate load and deflection of the beam with U-jackets were highly improved, and 2) the calculated deflection and strain correlated well with the measured values before the peeling failure.

  • Property of recycled concrete column encased by steel tube subjected to axial compression

    Katsuyuki Konno, Yasuhiko Sato, Yoshio Kakuta, Msaji Ohira

    Transactions of the Japan Concrete Institute   19   231 - 238  1997

     View Summary

    The property of recycled concrete column encased by steel tube subjected to axial compression was studied. It was found that the column, where progress of fracture is faster than the normal concrete, has enough capacity to be utilized though its rigidity and ultimate strength are smaller than those of the normal concrete.

  • Shear behavior of RC beams reinforced with carbon fiber sheet

    Yasuhiko Sato, Takayuki Tanaka, Tamon Ueda, Sadamu Ono

    Transactions of the Japan Concrete Institute   18   137 - 142  1996

     View Summary

    In this study, the shear resisting behavior of reinforced concrete (RC) beams with carbon fiber sheet (CFS) was examined experimentally. Shear strength of RC beams with CFS attached to the sides is defined as the summation of the shear force carried by concrete and the shear forces carried by stirrup and CFS in shear cracking zone. The concept for calculation of the shear forces carried by stirrup and CFS is also discussed.

  • Analytical prediction of cover cracking due to corrosion of reinforcement

    Hideki Kameya, Yasuhiko Sato, Tamon Ueda, Yoshio Kakuta

    Transactions of the Japan Concrete Institute   18   123 - 128  1996

     View Summary

    In this study splitting crack of cover concrete due to corrosion of reinforcing bar and the critical volume increment of the reinforcing bar which causes full penetration of the splitting crack to the concrete surface are analyzed by a nonlinear finite element method. As a result, relationships between the dimension of the surrounding concrete, which is the concrete cover and the bar spacing, and the characteristics of the splitting crack, which is its direction and the critical volume increment are clarified.

  • Shear strength of reinforced concrete deep beams with horizontal and vertical shear reinforcement

    Yasuhiko Sato, Tamon Ueda, Yoshio Kakuta

    Transactions of the Japan Concrete Institute   17   313 - 318  1995

     View Summary

    Based on the finite element analyses, the equation for shear strength of deep beams without shear reinforcement is modified to predict the shear strength of deep beams with horizontal and vertical shear reinforcement. It is confirmed that the modified equation can estimate the experimental results.

  • Study on failure criterion of FRP bent rods

    Hideyuki Kanematsu, Yasuhiko Sato, Akihisa Imamura, Tamon Ueda

    Transactions of the Japan Concrete Institute   16   205 - 210  1994

     View Summary

    Experiment on Fiber Reinforced Plastic (FRP) rods as shear reinforcement with the intersection of a shear crack in a beam is carried out in order to clarify the failure criterion of the FRP rod at the bent portion. The finite element analysis in which anisotropy of the FRP rod and bond slip between concrete and the FRP rod are considered, is also conducted. Strain and bond stress distributions of the FRP rod with bent portions are investigated in detail.

  • Analytical evaluation of shear resisting behavior of prestressed concrete beams reinforced with FRP rods

    Yasuhiko Sato, Tamon Ueda, Yoshio Kakuta

    Transactions of the Japan Concrete Institute   16   425 - 430  1994

     View Summary

    Non-linear finite element analysis is conducted in order to clarify the shear resisting behavior of prestressed concrete beams reinforced with FRP rods. Prestressing force, stiffness of tendon and web reinforcement are chosen as parameters. It is discussed how prestressing force and mechanical properties of reinforcement influence the shear strength as well as the shear force components in the shear resisting behavior.

▼display all

Misc

  • 隅角部補強ユニットを利用したL形隅角部の耐荷性能に関する実験的検討

    渡部孝彦, 村田裕志, 武田均, 佐藤靖彦

    コンクリート工学年次論文集(CD-ROM)   42  2020

    J-GLOBAL

  • 荷重履歴に着目したせん断補強筋を持たないRCはりの変形性状に関する検討

    竹田京子, 佐藤靖彦

    コンクリート工学年次論文集(CD-ROM)   42  2020

    J-GLOBAL

  • RC隅角部の配筋省力化技術の開発

    渡部孝彦, 村田裕志, 武田均, 佐藤靖彦

    大成建設技術センター報(CD-ROM)   ( 53 )  2020

    J-GLOBAL

  • Study on bonding behavior of FRP sheets and concrete bonded with high elongation elastic resin

    小林朗, 尾崎允彦, 佐藤靖彦, 荒添正棋, 立石晶洋, 小森篤也

    構造工学論文集 A(Web)   66A  2020

    J-GLOBAL

  • Quantitative evaluation of fatigue life for connection with rebar joint between precast PC slabs under wheel-type loads

    竹田京子, 佐藤靖彦

    構造工学論文集 A(Web)   66A  2020

    J-GLOBAL

  • 三次元有限要素解析による新しい鉄筋コンクリート隅角部構造の力学特性の評価

    吉光聖洋, 横田弘, 佐藤靖彦

    土木学会北海道支部論文報告集(CD-ROM)   ( 76 )  2020

    J-GLOBAL

  • MAINTENANCE OF NORTH BREAKWATER DOME IN WAKKANAI PORT USING DETERIORATION MAPPING

    長谷一矢, 横田弘, 佐藤靖彦

    土木学会論文集 E2(材料・コンクリート構造)(Web)   76 ( 4 )  2020

    J-GLOBAL

  • センサー機能付きCFRPプレートの付着特性と電気抵抗に関する検討

    立石晶洋, 佐藤靖彦, 高瀬祐一

    コンクリート工学年次論文集(CD-ROM)   41  2019

    J-GLOBAL

  • 疲労荷重下のせん断補強筋を有さないRC梁の損傷機構に関する解析的検討

    竹田京子, 佐藤靖彦

    プレストレストコンクリートの発展に関するシンポジウム論文集   28th  2019

    J-GLOBAL

  • 耐凍害性の向上を目的とした中空微小球のダムコンクリートへの適用実績

    渡部貴裕, 橋本学, 福井直之, 中村元郎, 室野井敏之, 林大介, 遠藤裕丈, 佐藤靖彦

    土木学会年次学術講演会講演概要集(CD-ROM)   74th  2019

    J-GLOBAL

  • コンクリートダムの施工における真空断熱材の越冬養生への適用実績

    室野井敏之, 福井直之, 中村元郎, 渡部貴裕, 山本秀哉, 佐藤靖彦

    土木学会年次学術講演会講演概要集(CD-ROM)   74th  2019

    J-GLOBAL

  • 継手によるプレキャストPC床版接合部の疲労耐久性の定量的評価

    竹田京子, 佐藤靖彦

    土木学会年次学術講演会講演概要集(CD-ROM)   74th  2019

    J-GLOBAL

  • ストランドシートで補強されたRC梁の曲げ耐力に関する実験的研究

    高橋義裕, 立石晶洋, 荒添正棋, 佐藤靖彦

    土木学会年次学術講演会講演概要集(CD-ROM)   74th  2019

    J-GLOBAL

  • せん断補強筋を持たないRCはりの静的載荷と疲労載荷による損傷過程と破壊機構に関する実験的検討

    竹田京子, 佐藤靖彦

    コンクリート構造物の補修,補強,アップグレード論文報告集(CD-ROM)   19  2019

    J-GLOBAL

  • FROST DAMAGE OF REINFORCED CONCRETE BEAMS AND ANALYTICAL EVALUATION OF ITS STATIC FAILURE BEHAVIOR

    金澤健, 佐藤靖彦, 高橋良輔

    土木学会論文集 E2(材料・コンクリート構造)(Web)   75 ( 4 )  2019

    J-GLOBAL

  • ひび割れと凍結融解作用による損傷を有するRC要素の1軸圧縮構成則の構築

    金澤健, 佐藤靖彦

    コンクリート工学年次論文集(CD-ROM)   40  2018

    J-GLOBAL

  • 支持条件と階段状漸増載荷の影響を考慮に入れた輪荷重走行試験におけるRC床版の疲労寿命予測に関する検討

    竹田京子, 佐藤靖彦

    コンクリート工学年次論文集(CD-ROM)   40  2018

    J-GLOBAL

  • 輪荷重走行試験におけるPC床版の疲労寿命予測に関する検討

    竹田京子, 佐藤靖彦

    プレストレストコンクリートの発展に関するシンポジウム論文集   27th  2018

    J-GLOBAL

  • 既設コンクリート構造物の構造性能評価研究小委員会報告書

    佐藤靖彦, 山本佳士, 上田尚史, 高橋良輔, 林大輔, 松本浩嗣, 伊藤始, 川口和広, 田所敏弥, 中村拓郎, 久末賢一, 保坂克也, 三好俊康, 村上祐貴, 谷田部勝博, 楊克倹

    コンクリート技術シリーズ   ( 116 )  2018

    J-GLOBAL

  • 3次元非線形有限要素解析による凍結融解作用を受けた鉄筋コンクリートはりの静的破壊挙動の評価

    金澤健, 佐藤靖彦, 高橋良輔

    コンクリート技術シリーズ   ( 116 )  2018

    J-GLOBAL

  • 凍結融解作用を受けた鉄筋コンクリート要素に生じる膨張の異方性

    金澤健, 佐藤靖彦

    土木学会年次学術講演会講演概要集(CD-ROM)   73rd  2018

    J-GLOBAL

  • 輪荷重走行試験におけるRC床版のせん断耐力低下を考慮した階段状漸増載荷の評価

    竹田京子, 佐藤靖彦

    土木学会年次学術講演会講演概要集(CD-ROM)   73rd  2018

    J-GLOBAL

  • RCボックスカルバートの隅角部に配する鉄筋ユニットブロック単体の力学的挙動についての解析

    吉光聖洋, 渡部孝彦, 武田均, 佐藤靖彦

    土木学会北海道支部論文報告集(CD-ROM)   ( 74 )  2018

    J-GLOBAL

  • 旧築別橋載荷試験におけるサンプリングモアレ法による変位計測

    安宍太郎, 佐藤靖彦, 前田芳巳, 大島義信

    土木学会北海道支部論文報告集(CD-ROM)   ( 74 )  2018

    J-GLOBAL

  • モアレ法を用いたひび割れ幅計測に関する基礎実験

    牛尾佳那子, 佐藤靖彦, 前田芳巳, 津田仁

    土木学会北海道支部論文報告集(CD-ROM)   ( 74 )  2018

    J-GLOBAL

  • 日本と欧米のあと施工アンカー設計手法の比較

    高橋宗臣, 佐藤靖彦, 石原力也

    コンクリート工学年次論文集(CD-ROM)   40  2018

    J-GLOBAL

  • 高炉スラグ細骨材を用いたコンクリートに関する研究小委員会(354委員会)成果報告書

    綾野克紀, 佐川康貴, 上野敦, 佐藤靖彦, 皆川浩, 青木優介, 井手一雄, 浦野真次, 齊藤和秀, 鈴木雅博, 高橋克則, 田中博一, 千々和伸浩, 中村英佑, 橋本親典, 橋本勝文, 藤井隆史, 二井谷教治, 柄澤英明, 細谷多慶, 蓑宮芳和, 森英一郎, 山越陽介, 吉澤千秋, YOGARAJHA Flakneswaran, 俵道和, 山田悠二

    コンクリート技術シリーズ   ( 117 )  2018

    J-GLOBAL

  • 鉄筋コンクリート隅角部における新しいユニット構造の耐荷機構の解析的評価

    吉光聖洋, 渡部孝彦, 武田均, 佐藤靖彦

    土木学会年次学術講演会講演概要集(CD-ROM)   73rd  2018

    J-GLOBAL

  • Investigation and Preventive Repair Strategy for North Breakwater Dome at Wakkanai Port

    横田弘, 佐藤靖彦, 吉田勝則

    コンクリート工学   55 ( 4 )  2017

    J-GLOBAL

  • 移動輪荷重下に置かれるRC床版の疲労寿命に関する解析的検討

    竹田京子, 佐藤靖彦

    土木学会北海道支部論文報告集(CD-ROM)   ( 73 )  2017

    J-GLOBAL

  • 各種要因が接着系あと施工アンカーの付着耐力に及ぼす影響

    佐原愛士, 佐藤靖彦, 高橋宗臣, 石原力也

    土木学会北海道支部論文報告集(CD-ROM)   ( 73 )  2017

    J-GLOBAL

  • 移動輪荷重下におけるRC床版の疲労耐久性評価式の提案

    濱田那津子, 佐藤靖彦

    土木学会北海道支部論文報告集(CD-ROM)   ( 73 )  2017

    J-GLOBAL

  • サンプリングモアレ法によるRC桁およびPC桁の変位計測

    高沢優人, 佐藤靖彦, 前田芳美, 津田仁

    土木学会北海道支部論文報告集(CD-ROM)   ( 73 )  2017

    J-GLOBAL

  • ポリウレア樹脂層を有するFRPシートとコンクリート間の付着機構に関する検討

    樺木達也, 佐藤靖彦

    土木学会北海道支部論文報告集(CD-ROM)   ( 73 )  2017

    J-GLOBAL

  • 上面増厚の厚さと付着界面の特性に着目したRCはり部材の挙動解析

    柳沼喜大, 佐藤靖彦

    土木学会北海道支部論文報告集(CD-ROM)   ( 73 )  2017

    J-GLOBAL

  • 凍結融解作用による鉄筋とコンクリート間の付着劣化機構とそのモデル化

    金澤健, 佐藤靖彦

    構造工学論文集 A(CD-ROM)   63  2017

    J-GLOBAL

  • 輪荷重走行試験におけるRC床版の疲労寿命予測に関する一検討

    竹田京子, 濱田那津子, 佐藤靖彦

    プレストレストコンクリートの発展に関するシンポジウム論文集   26th  2017

    J-GLOBAL

  • 各種要因が接着系あと施工アンカーの付着耐力に及ぼす影響に関する実験的検討

    佐原愛士, 佐藤靖彦, 高橋宗臣, 石原力也

    コンクリート構造物の補修,補強,アップグレード論文報告集   17  2017

    J-GLOBAL

  • 移動輪荷重下におけるRC床版の疲労耐久性評価式の提案

    濱田那津子, 濱田那津子, 竹田京子, 佐藤靖彦

    土木学会年次学術講演会講演概要集(CD-ROM)   72nd  2017

    J-GLOBAL

  • 炭素繊維シートで補強されたRC桁のせん断耐力に関する実験的研究

    高橋義裕, 立石晶洋, 荒添正棋, 佐藤靖彦

    土木学会年次学術講演会講演概要集(CD-ROM)   72nd  2017

    J-GLOBAL

  • 実橋梁の変位測定および測定結果に基づく曲げ剛性評価に関する一検討

    高沢優人, 高沢優人, 佐藤靖彦, 前田芳巳, 津田仁

    土木学会年次学術講演会講演概要集(CD-ROM)   72nd  2017

    J-GLOBAL

  • Experimental Investigation of Load Bearing Capacity of RC Beam under the Combined Deterioration of Fatigue Followed by Frost Damage

    林田宏, 佐藤靖彦, 上田多門

    寒地土木研究所月報   ( 754 ) 2 - 8  2016.03

    CiNii J-GLOBAL

  • 稚内港北防波堤ドームの劣化度評価および補修計画の立案

    上田裕章, 吉田勝則, 横田弘, 佐藤靖彦

    土木学会北海道支部論文報告集(CD-ROM)   ( 72 )  2016

    J-GLOBAL

  • 積雪寒冷地に約40年供用されたダムコンクリートのスケーリング抵抗性に関する実験的検討

    竹田京子, 佐藤靖彦, 長谷川武春

    土木学会北海道支部論文報告集(CD-ROM)   ( 72 )  2016

    J-GLOBAL

  • セメント種類が高温に曝されたモルタルのひび割れ性状に及ぼす影響

    小山ゆりえ, RONGVIRIYAPANICH Onnicha, 佐藤靖彦

    土木学会北海道支部論文報告集(CD-ROM)   ( 72 )  2016

    J-GLOBAL

  • 骨材界面の強度の変化がモルタルの力学的挙動に及ぼす影響

    羽根佑歩, 佐藤靖彦

    土木学会北海道支部論文報告集(CD-ROM)   ( 72 )  2016

    J-GLOBAL

  • 凍結融解作用による損傷を考慮したRCはり部材の3次元非線形有限要素解析

    金澤健, 佐藤靖彦, 高橋良輔, 林田宏

    コンクリート構造物の補修,補強,アップグレード論文報告集   16  2016

    J-GLOBAL

  • 劣化-構造連成解析による硫酸環境下のRCはり部材の残存耐力予測

    渡部孝彦, 佐藤靖彦

    コンクリート構造物の補修,補強,アップグレード論文報告集   16  2016

    J-GLOBAL

  • 積雪寒冷地のダムコンクリートのスケーリング抵抗性とその進行予測

    竹田京子, 佐藤靖彦, 長谷川武春

    コンクリート構造物の補修,補強,アップグレード論文報告集   16  2016

    J-GLOBAL

  • 積雪寒冷地のダムコンクリートのスケーリング進行予測に関する検討

    竹田京子, 佐藤靖彦, 長谷川武春

    土木学会年次学術講演会講演概要集(CD-ROM)   71st  2016

    J-GLOBAL

  • ストランドシートで下面補強されたRC桁の曲げ耐力に関する実験的研究

    高橋義裕, 小林朗, 荒添正棋, 佐藤靖彦

    土木学会年次学術講演会講演概要集(CD-ROM)   71st  2016

    J-GLOBAL

  • 積雪寒冷地のコンクリートダムのスケーリングに対する抵抗性について

    米坂俊介, 佐藤靖彦, 佐藤英隆

    土木学会年次学術講演会講演概要集(CD-ROM)   71st  2016

    J-GLOBAL

  • 硫酸劣化を生じた鉄筋コンクリート部材の寿命予測解析

    渡部孝彦, 佐藤靖彦

    土木学会年次学術講演会講演概要集(CD-ROM)   71st  2016

    J-GLOBAL

  • 面取り部に接着された炭素繊維シートの曲げ引張強度および付着特性

    立石晶洋, 小林朗, 荒添正棋, 佐藤靖彦, 高橋義裕

    土木学会年次学術講演会講演概要集(CD-ROM)   71st  2016

    J-GLOBAL

  • コンクリート圧縮強度がポリウレア樹脂層を有するストランドシート-コンクリート間の付着特性に及ぼす影響

    荒添正棋, 小林朗, 高橋義裕, 佐藤靖彦

    土木学会年次学術講演会講演概要集(CD-ROM)   71st  2016

    J-GLOBAL

  • 低温および高温環境下に置かれる接着系あと施工アンカーの付着耐力について

    宮崎剛, 佐藤靖彦, 佐原愛士, 高橋宗臣

    土木学会年次学術講演会講演概要集(CD-ROM)   71st  2016

    J-GLOBAL

  • 低温および高温環境下に置かれる接着系あと施工アンカーの温度モニタリングについて

    高橋宗臣, 佐藤靖彦, 佐原愛士, 宮崎剛

    土木学会年次学術講演会講演概要集(CD-ROM)   71st  2016

    J-GLOBAL

  • 凍結融解作用による損傷機構に基づいた鉄筋とコンクリート間の付着劣化モデル

    金澤健, 佐藤靖彦

    土木学会年次学術講演会講演概要集(CD-ROM)   71st  2016

    J-GLOBAL

  • あと施工アンカーの耐久性の評価方法の確立と設計の高度化研究委員会 委員会報告書

    国枝稔, 杉山智昭, 内田慎哉, 有木克良, 山崎大輔, 長井宏平, 加藤絵万, 濱崎仁, 大垣正之, 高橋宗臣, 安藤重裕, 伊藤嘉則, 西崎到, 中野克彦, 佐藤靖彦, 向井智久, 笠裕一郎, 田所敏弥, 井口重信, 坂岡和寛, 西田宏司

    日本コンクリート工学会論文集   JCI-C90  2016

    J-GLOBAL

  • 硫酸劣化を考慮した持続荷重を受ける無筋コンクリートはりの破壊解析

    渡部孝彦, 佐藤靖彦

    コンクリート工学年次論文集(CD-ROM)   38  2016

    J-GLOBAL

  • Assessment Method of Structural Performance of Existing Bridges Based on Simple Inspections

    佐藤靖彦, 渡辺忠朋, 橋本一, 北島幹士

    コンクリート工学   53 ( 2 )  2015

    J-GLOBAL

  • 既設橋梁の構造性能判定法の提案-材料の維持管理から構造物の維持管理への転換へ向けて-

    佐藤靖彦, 渡邊忠朋, 橋本一, 北島幹士, 清兼誠司

    橋梁と基礎   49 ( 6 )  2015

    J-GLOBAL

  • 骨材がカルシウム溶脱を生じたコンクリートの力学的特性に与える影響についての基礎的研究

    今野克幸, 佐藤靖彦

    セメント技術大会講演要旨(CD-ROM)   69th  2015

    J-GLOBAL

  • 2020年の橋梁 2章 橋梁関連の技術 コンクリート構造の設計と維持管理の連携

    佐藤靖彦, 横田弘

    橋梁と基礎   49 ( 8 )  2015

    J-GLOBAL

  • Relationships Between Transformation of Cement Hydrates and Meso-scale Mechanical Characteristics of Mortar Deteriorated by Sulfate Attack

    三浦泰人, 佐藤靖彦, 中村光

    コンクリート工学論文集(Web)   26  2015

    J-GLOBAL

  • 疲労後に凍害を与えて複合劣化させたRCはり部材の耐荷性能

    林田宏, 佐藤靖彦

    土木学会年次学術講演会講演概要集(CD-ROM)   70th  2015

    J-GLOBAL

  • 骨材および骨材界面領域がCa溶脱性状に及ぼす影響の解析的評価

    三浦泰人, 佐藤靖彦, 中村光

    土木学会年次学術講演会講演概要集(CD-ROM)   70th  2015

    J-GLOBAL

  • 断面修復厚さがRC部材の破壊性状に及ぼす影響

    柳沼喜大, 佐藤靖彦, 太田哲司, 花田剛志

    土木学会年次学術講演会講演概要集(CD-ROM)   70th  2015

    J-GLOBAL

  • ポリウレア樹脂変形層を用いて炭素繊維シート補強したRC梁のせん断補強実験

    荒添正棋, 小林朗, 高橋義裕, 佐藤靖彦

    土木学会年次学術講演会講演概要集(CD-ROM)   70th  2015

    J-GLOBAL

  • ストランドシート補強RC梁の曲げ挙動に与えるコンクリート強度の影響について

    高橋義裕, 小林朗, 荒添正棋, 佐藤靖彦

    土木学会年次学術講演会講演概要集(CD-ROM)   70th  2015

    J-GLOBAL

  • 寒冷条件に置かれる接着系あと施工アンカーの引張耐力の評価

    佐原愛士, 佐藤靖彦, 高橋宗臣, 櫻井和人

    土木学会年次学術講演会講演概要集(CD-ROM)   70th  2015

    J-GLOBAL

  • 実橋から切り出したRC床版を対象とした補修効果について

    柳沼喜大, 佐藤靖彦, 太田哲司, 花田剛志

    土木学会北海道支部論文報告集(CD-ROM)   ( 71 )  2015

    J-GLOBAL

  • 橋梁の構造性能点検診断法に基づく対策の考え方に関する一考察

    高沢優人, 佐藤靖彦

    土木学会北海道支部論文報告集(CD-ROM)   ( 71 )  2015

    J-GLOBAL

  • 接着系アンカーの引抜き力に対する設計式の比較検討

    佐原愛士, 佐藤靖彦, 高橋宗臣, 櫻井和人

    土木学会北海道支部論文報告集(CD-ROM)   ( 71 )  2015

    J-GLOBAL

  • 実橋梁を用いた既存の判定法と構造性能判定法の試行的比較

    高沢優人, 佐藤靖彦, 長谷川直久, 北島幹士

    土木学会年次学術講演会講演概要集(CD-ROM)   70th  2015

    J-GLOBAL

  • 疲労と凍害で複合劣化したRCはりの耐荷力に関する実験的検討

    林田宏, 佐藤靖彦

    コンクリート構造物の補修,補強,アップグレード論文報告集   15  2015

    J-GLOBAL

  • 析出物の影響を考慮した硫酸による劣化予測解析による劣化領域の評価

    三浦泰人, 佐藤靖彦, 中村光

    コンクリート構造物の補修,補強,アップグレード論文報告集   15  2015

    J-GLOBAL

  • コンクリート構造物の安全確保のためのシステムに関する研究小委員会成果報告書

    鎌田敏郎, 国枝稔, 秋山充良, 浅本晋吾, 大島義信, 服部晋一, 三木朋広, 山村正人, 石田雅博, 今井卓也, 稲葉尚文, 岩波光保, 笠井尚哉, 小林薫, 佐藤靖彦, 竹田宣典, 長縄卓夫, 福永靖雄, 堀倫裕, 松田浩, 森雅司

    コンクリート技術シリーズ   ( 108 )  2015

    J-GLOBAL

  • 示方書連絡調整小委員会報告書-次世代の「コンクリート標準示方書」に向けて-

    佐藤靖彦, 秋山充良, 石田哲也, 伊代田岳史, 加藤佳孝, 斉藤成彦, 牧剛史, 山本貴士, 浅田尚, 浅本晋吾, 阿波稔, 岩波光保, 上田隆雄, 上田尚史, 上田洋, 臼井達哉, 大島正記, 片健一, 加藤絵万, 国枝稔, 蔵重勲, 古賀裕久, 小林孝一, 齋藤隆, 坂井吾郎, 坂口淳一, 佐川康貴, 桜井邦昭, 塩畑英俊, 田所敏弥, 田中博一, 田中泰司, 千々和伸浩, 築嶋大輔, 土屋智史, 長井宏平, 半井健一郎, 西田孝弘, 日比野誠, HENRY Michael

    コンクリート技術シリーズ   ( 107 )  2015

    J-GLOBAL

  • 鉄筋コンクリート構造の疲労破壊-破壊機構と性能評価の将来像を探る-

    岩城一郎, 佐藤靖彦, 土屋智史, 春日昭夫, 子田康弘, 中島章典, 田中泰司, 渡辺忠朋, 藤山知加子, 阿合延明, 千々和伸浩, 荒井明夫, 檀勤, 石田哲也, 中野聡, 磯部龍太郎, 中村拓郎, 江頭慶三, 兵頭彦次, 尾上幸造, 林田宏, 門万寿男, 平塚慶達, 上原子晶久, 古内仁, 河村直哉, 細田暁, 小松怜史, 細野宏巳, 斉藤成彦, 牧剛史, 坂口淳一, 松崎裕, 定歳道夫, 松本浩嗣, 鈴木康範, 森本仁志, 高橋茂樹, 渡辺健, 田中喜一郎

    コンクリート技術シリーズ   ( 109 )  2015

    J-GLOBAL

  • 化学的劣化により変質したメゾレベルのモルタルの力学的性質の関係性評価

    三浦泰人, 佐藤靖彦, 中村光

    コンクリート工学年次論文集(CD-ROM)   37 ( 1 ) 715-720  2015  [Refereed]

    Rapid communication, short report, research note, etc. (scientific journal)  

     View Summary

    モルタルのメゾレベルの試験体を用いてイオン交換水,NaCl溶液,硫酸溶液による浸漬実験を行った。浸漬後,力学試験および物理化学的性質を同定することで,Ca溶脱および硫酸による劣化が生じた試験体の力学的性質の変化を評価した。具体的には,浸漬後の試験体を用いて曲げ試験を行うとともに,得られた荷重変位曲線から逆解析を行うことで力学的性質を同定した。加えて,同一試験体を用いて化学的劣化により変化する物理化学的性質を測定した。さらに,既往の曲げ強度の推定式を基に,化学的劣化に伴って変化する各力学的性質の関連性を評価した。

    J-GLOBAL

  • Relationships Between Transformation of Cement Hydrates and Meso-scale Mechanical Characteristics of Mortar Deteriorated by Sulfate Attack

    Miura Taito, Sato Yasuhiko, Nakamura Hikaru

    Concrete Research and Technology   26 ( 0 ) 1 - 9  2015

     View Summary

    In this study, meso-scale thin mortar specimens were immersed in a sulfuric acid solution for 60 days and then subjected to three-point bending tests and shear tests to clarify the mechanical behaviors of mortar in containing cement hydrates transubstantiated under sulfate attack. In particular, tensile behaviors, namely elastic modulus, tensile strength and fracture energy, and shear strength, were determined from the load-displacement curves using back analysis and shear tests, respectively. Following the mechanical tests, chemical analyses were also carried out to clarify how the amount of hydrates, which were quantities of CH and C-S-H, the existence of precipitates, porosity and pore volume distribution affect mechanical characteristics. As a result, it was found that the relationships between physico-chemical properties and elastic modulus and tensile strength differ from the relationships between physico-chemical properties and fracture energy and shear strength. Furthermore, the applicability of the proposed model based on the relationships between porosity and strength was verified through comparison of the calculated and experimental results.

    DOI CiNii

  • 凍結融解作用および塩化物イオンの浸透に伴うセメント硬化体特性の変化

    橋本勝文, 横田弘, 佐藤靖彦, 杉山隆文

    セメント・コンクリート   ( 803 )  2014

    J-GLOBAL

  • 高温にさらされたモルタルのひび割れ性状の観察

    石塚智美, RONGVIRIYAPANICH Onnicha, 佐藤靖彦

    土木学会北海道支部論文報告集(CD-ROM)   ( 70 )  2014

    J-GLOBAL

  • Establishment of JSCE Recommendations for Design and Construction of Post-installed Anchors in Concrete

    梅原秀哲, 中村光, 新藤竹文, 佐藤靖彦, 古市耕輔

    コンクリート工学   52 ( 7 )  2014

    J-GLOBAL

  • Evaluation of Relationships Between Mechanical Characteristics and Physico-Chemical Properties of Mortar Influenced by Ca Leaching at Meso-Scale Level

    三浦泰人, 佐藤靖彦

    コンクリート工学論文集(Web)   25  2014

    J-GLOBAL

  • メソスケールでの引張強度のばらつきがコンクリートの圧縮破壊に及ぼす影響の解析的評価

    今野克幸, 小野達仁, 佐藤靖彦

    コンクリート工学年次論文集(CD-ROM)   36  2014

    J-GLOBAL

  • ポリウレア樹脂層を有する炭素繊維シート補強工法の高温時における付着特性に関する研究

    新井崇裕, 山野辺慎一, 荒添正棋, 佐藤靖彦, 佐藤靖彦

    コンクリート工学年次論文集(CD-ROM)   36  2014

    J-GLOBAL

  • ストランドシート補強RCはりの曲げ耐力

    高橋義裕, 小林朗, 荒添正棋, 佐藤靖彦

    土木学会年次学術講演会講演概要集(CD-ROM)   69th  2014

    J-GLOBAL

  • 準微視的スケールでのモルタルの物理・化学的性質に及ぼす硫酸濃度の影響

    渡部孝彦, 佐藤靖彦

    土木学会年次学術講演会講演概要集(CD-ROM)   69th  2014

    J-GLOBAL

  • 凍結融解作用を受けたコンクリート中の鉄筋の付着構成則に関する考察

    金澤健, 佐藤靖彦, 三河智将

    土木学会年次学術講演会講演概要集(CD-ROM)   69th  2014

    J-GLOBAL

  • 高温時におけるポリウレア樹脂層を有する炭素繊維シート補強工法の付着特性(2)-解析的検討-

    新井崇裕, 山野辺慎一, 荒添正棋, 小林朗, 佐藤靖彦

    土木学会年次学術講演会講演概要集(CD-ROM)   69th  2014

    J-GLOBAL

  • 高温時におけるポリウレア樹脂層を有する炭素繊維シート補強工法の付着特性(1)-実験的検討-

    荒添正棋, 小林朗, 山野辺慎一, 新井崇裕, 佐藤靖彦

    土木学会年次学術講演会講演概要集(CD-ROM)   69th  2014

    J-GLOBAL

  • 疲労と凍害の複合劣化を受けたコンクリートの圧縮強度と超音波伝播速度を用いた劣化度評価に関する基礎的検討

    林田宏, 佐藤靖彦

    土木学会年次学術講演会講演概要集(CD-ROM)   69th  2014

    J-GLOBAL

  • 化学的劣化がメソスケールモルタルの寸法効果に及ぼす影響に関する解析的検討

    渡部孝彦, 佐藤靖彦, 三浦泰人

    土木学会北海道支部論文報告集(CD-ROM)   ( 70 )  2014

    J-GLOBAL

  • 有限要素解析によるディープビームのせん断破壊評価に関する基礎検討

    土田僚, 渡辺亘司, 佐藤靖彦

    土木学会北海道支部論文報告集(CD-ROM)   ( 70 )  2014

    J-GLOBAL

  • 構造性能評価に基づく点検・診断法による中小橋梁の性能予測

    佐藤靖彦, 渡辺忠朋

    日本学術会議材料工学連合講演会講演論文集   58th  2014

    J-GLOBAL

  • 疲労と凍害の複合劣化を受けたコンクリートの力学特性評価に関する基礎的検討

    林田宏, 佐藤靖彦

    コンクリート構造物の補修,補強,アップグレード論文報告集   14  2014

    J-GLOBAL

  • コンクリート構造物の設計と維持管理の連係による性能確保システム研究小委員会成果報告書

    横田弘, 佐藤靖彦, 岩城一郎, 岩波光保, 上田洋, 木村嘉富, 武若耕司, 野島昭二, 信田佳延, 村上祐貴, 山本平, 渡辺忠朋

    コンクリート技術シリーズ   ( 105 )  2014

    J-GLOBAL

  • NUMERICAL ANALYSIS FOR MORTAR DEGRADATED BY SULFATE ACID ATTACK CONSIDERING INFLUENCES OF ETTRINGITE AND GYPSUM

    三浦泰人, 佐藤靖彦

    セメント・コンクリート論文集   67 ( 1 ) 216 - 223  2014

     View Summary

    The purpose of this study is to develop the analytical method which can evaluate the change in physico-chemical property of mortar immersed in sulfuric acid solution. In this analytical approach, influences of sulfate acid attack were considered by diffusivity change of sulfate ions and physical change caused by chemical reaction of cement hydrate with sulfate ions. In the analysis, deposition condition of ettringite and gypsum was given by pH value and porosity which were calculated by the change in cement hydrate based on the experimental results. Finally, the validity of the analysis was discussed through parametric analyses in which the porosity value was varied.

    DOI CiNii J-GLOBAL

  • Evaluation of Relationships Between Mechanical Characteristics and Physico-Chemical Properties of Mortar Influenced by Ca Leaching at Meso-Scale Level

    Miura Taito, Sato Yasuhiko

    Concrete Research and Technology   25 ( 0 ) 109 - 118  2014

     View Summary

    In this study, thin mortar specimens were immersed in either ion exchanged water or NaCl solution for 360 days for the purpose of evaluating the relationships between changes in mechanical characteristics and physico-chemical properties caused by Ca leaching. Following the immersion test, bending and shear tests were carried out to determine the elastic modulus, flexural strength, tensile strength, fracture energy, tensile softening curve and shear strength. Furthermore, physico-chemical properties such as calcium hydroxide and porosity were also determined by chemical analysis. Based on these results, the relationships between the mechanical characteristics and physico-chemical properties were evaluated. Bending strength, tensile strength, fracture energy and shear strength were found to be strongly related to the amount of cement hydrate and porosity, both for the ion exchanged water immersed and the NaCl solution immersed specimens.

    DOI CiNii

  • Integrated Evaluation of Structural Performance over Time of Concrete Structures with Chloride Induced Damage

    三島徹也, 山本貴士, 大下英吉, 金久保利之, 国枝稔, 佐藤靖彦, 秋山充良, 上原子晶久, 村上祐貴

    コンクリート工学   52 ( 3 ) 243 - 250  2014

     View Summary

    This paper presents some of the results achieved by Technical Committee on Systematization to Evaluate Structure and Durability Performance in Corroded RC Structure, which works to establish the use of numerical structural analysis as an evaluation method that allows numerical representation in space and time of durability of concrete structures with chloride induced damage(hereinafter, structural performance over time), and an index of structural performance over time allowing the evaluation of total structural systems. This paper covers in particular methods to evaluate the spatial variability of the amount of corrosion that affects structural performance using probabilistic and statistical techniques, and constitutive models related to reinforcement corrosion and the bond between concrete and corroded reinforcement, which are essential for the finite element analysis of corroded concrete structures. Further, an index of structural performance over time is proposed and formulated, and trial calculation results for total structural systems are introduced.

    DOI CiNii J-GLOBAL

  • Revisions in "Design" Volume of Standard Specifications for Concrete Structures 2012

    MAEKAWA K., SATO T., WATANABE T., SHIMOMURA T., NAKAMURA H., SATO Y., MARUYA T., MISHIMA T.

    Concrete Journal   51 ( 6 ) 488 - 492  2013.06

     View Summary

    This document outlines the revisions made to the “Design” volume of the Standard Specifications for Concrete Structures 2012. The aim of these revisions was to raise the level of performance assessment and verification methods, building on the basic organization of the 2007 version and drawing from advances in technology in the past few years. Specifically, various technical items, including chloride attack and steel corrosion, volume change of concrete (drying shrinkage, autogenous shrinkage, temperature change), prediction of cracking, shear strength formula, long-term deformation of structures, nonlinear analysis, restorability of structures and repairability of members, have been revised and mutual consistency has been enhanced.

    DOI CiNii

  • 鉄筋腐食したコンクリート構造物の構造・耐久性能評価の体系化研究委員会

    三島徹也, 山本貴士, 大下英吉, 金久保利之, 国枝稔, 佐藤靖彦

    コンクリート工学年次論文集(CD-ROM)   35  2013

    J-GLOBAL

  • ポリウレア樹脂を柔軟層として使用した連続繊維シートによるRC梁のせん断補強効果の実験的評価

    荒添正棋, 小林朗, 高橋義裕, 佐藤靖彦

    コンクリート工学年次論文集(CD-ROM)   35  2013

    J-GLOBAL

  • イオン交換水に浸漬させたモルタルの物理化学的性質と力学的性質の関係

    三浦泰人, 佐藤靖彦, 今野克幸, GERDES Andreas

    コンクリート工学年次論文集(CD-ROM)   35  2013

    J-GLOBAL

  • ポリウレア樹脂層を有するストランドシート補強RCはりの曲げ挙動

    高橋義裕, 小林朗, 荒添正棋, 佐藤靖彦

    土木学会年次学術講演会講演概要集(CD-ROM)   68th  2013

    J-GLOBAL

  • 希硫酸溶液に浸漬させたモルタルの物理・化学・力学的性質

    渡辺亘司, 三浦泰人, 佐藤靖彦

    土木学会年次学術講演会講演概要集(CD-ROM)   68th  2013

    J-GLOBAL

  • ポリウレア変形層を介して炭素繊維シートを接着補強したRC梁のせん断補強実験

    荒添正棋, 小林朗, 高橋義裕, 佐藤靖彦

    土木学会年次学術講演会講演概要集(CD-ROM)   68th  2013

    J-GLOBAL

  • 凍結融解作用を受けたコンクリートの圧縮特性に関する一考察

    金澤健, 佐藤靖彦

    土木学会年次学術講演会講演概要集(CD-ROM)   68th  2013

    J-GLOBAL

  • 塩化物イオンによるセメント硬化体の変質および物質透過性

    城ケ崎雄太, 横田弘, 橋本勝文, 佐藤靖彦, 三浦泰人

    コンクリート構造物の補修,補強,アップグレード論文報告集   13  2013

    J-GLOBAL

  • 配合条件がモルタルの引張軟化特性に及ぼす影響

    大河内孝彦, 三浦泰人, 佐藤靖彦

    土木学会北海道支部論文報告集(CD-ROM)   ( 69 )  2013

    J-GLOBAL

  • 炭素繊維ストランドシートとコンクリート間の付着強度に関する検討

    天羽健, 佐藤靖彦, 荒添正棋, 小林朗

    土木学会北海道支部論文報告集(CD-ROM)   ( 69 )  2013

    J-GLOBAL

  • 常温・低温下におけるポリウレア樹脂層を有する炭素繊維ストランドシートの付着耐力

    小川泰成, 佐藤靖彦, 小林朗, 荒添正棋

    土木学会年次学術講演会講演概要集(CD-ROM)   68th  2013

    J-GLOBAL

  • 界面にポリウレア樹脂を塗布されたCFRPストランドシート補強RCはりの曲げ挙動に関する実験的研究

    高橋義裕, 荒添正棋, 小林朗, 佐藤靖彦

    コンクリート工学年次論文集(CD-ROM)   35  2013

    J-GLOBAL

  • Prediction of Dry Shrinkage of Concrete Made with Recycled Coarse Aggregate

    Konno Katsuyuki, Sato Yasuhiko, Katsura Osamu, Okuyama Hidetoshi

    Concrete Research and Technology   24 ( 3 ) 135 - 148  2013

     View Summary

    The cement paste adhering to recycled aggregate increases the unit weight of water and reduces the confinement effect of aggregate. Therefore, the authors presented a method to estimate the increase in unit weight of water and the reduction of the confinement effect of aggregate by means of regression analyses using data in references. Next, a formula to predict dry shrinkage for concrete made with recycled coarse aggregate, based on the JSCE prediction formula for normal concrete, was developed by taking into account the increase in unit weight of water and the reduction of the confinement effect of aggregate. Since the proposed method does not require any tests to estimate the characteristics of the cement paste adhering to recycled aggregate, it allows easy calculation of shrinkage strain. As a result of verification using prior experimental results, it was concluded that the predicted value of dry shrinkage of recycled concrete has sufficient precision comparable to that of the prediction of dry shrinkage of normal concrete using the JSCE prediction formula.

    DOI CiNii

  • Revisions in "Design" Volume of Standard Specifications for Concrete Structures 2012

    Maekawa K, Sato T, Watanabe T, Shimomura T, Nakamura H, Sato Y, Maruya T, Mishima T

    Concrete Journal (Tokyo. 1963)   51 ( 6 ) 488 - 492  2013

     View Summary

    This document outlines the revisions made to the "Design" volume of the Standard Specifications for Concrete Structures 2012. The aim of these revisions was to raise the level of performance assessment and verification methods, building on the basic organization of the 2007 version and drawing from advances in technology in the past few years. Specifically, various technical items, including chloride attack and steel corrosion, volume change of concrete (drying shrinkage, autogenous shrinkage, temperature change), prediction of cracking, shear strength formula, long-term deformation of structures, nonlinear analysis, restorability of structures and repairability of members, have been revised and mutual consistency has been enhanced.

    DOI CiNii

  • Application of Recycled Aggregate Concrete to the Concrete around Turbines in the Redevelopment Construction of Hydroelectric Power Plant

    ISHIGURO T, KITSUI K, MINETA M, SAITO T, SATO Y

    Concrete Journal (Tokyo. 1963)   50 ( 11 ) 998 - 1005  2012.11

     View Summary

    Application example of recycled aggregate concrete is extremely few even though many studies on quality of recycled aggregates for the structural concrete have been conducted so far. Based on several experimental investigations, therefore, we have attempted an application of low quality recycled coarse aggregates, which are made from demolished concrete of an old hydroelectric power plant, to renovation work of the power plant. In this paper, both the characteristics of the recycled aggregate concrete and cost performance of this project are reported.

    DOI CiNii

  • 第3回建設分野におけるFRPに関するアジア太平洋国際会議 (The Third Asia-Pacific Conference on FRP in Structures (APFIS 2012)) の開催・参加報告

    佐藤 靖彦, 下村 匠, 金久保 利之

    コンクリート工学 = Concrete journal   50 ( 6 ) 564 - 565  2012.06

    DOI CiNii

  • U字補強を有するストランドシート補強RCはりの曲げ挙動

    高橋義裕, 小林朗, 荒添正棋, 佐藤靖彦

    土木学会年次学術講演会講演概要集(CD-ROM)   67th  2012

    J-GLOBAL

  • Degradation and Cracking of Permanent Bricks of Steel Ladles : Long Term Destruction of Refractories -1-

    GOTO K., MIKI T., KIYOTA Y., TAKEUCHI T., TAKEUCHI H., HINO Y., KASAI A., SAKAGUCHI N., OSUGI Y., WADA A., NISHIZAWA S., OKITA K., UEDA T., SATO Y., MATSUMOTO H., LI Xiaodong

    耐火物 = Refractories   63 ( 2 ) 94 - 95  2011.02

    CiNii

  • Static and Fatigue Properties of Typical Refractory : Long Term Destruction of Refractories -2-

    LI Xiaodong, GOTO K., MIKI T., KIYOTA Y., TAKEUCHI T., TAKEUCHI H., HINO Y., KASAI A., SAKAGUCHI N., OSUGI Y., WADA A., NISHIZAWA S., OKITA K., UEDA T., SATO Y., MATSUMOTO H.

    耐火物 = Refractories   63 ( 2 ) 96 - 97  2011.02

    CiNii

  • 凍結防止剤の種類に着目した凍結融解後のモルタルの力学特性

    横山直樹, 佐藤靖彦, 橋本勝文, 三浦泰人

    土木学会北海道支部論文報告集(CD-ROM)   ( 67 )  2011

    J-GLOBAL

  • 硫酸溶液に浸漬させたモルタルの引張特性に関する実験的評価

    三浦泰人, 佐藤靖彦

    土木学会北海道支部論文報告集(CD-ROM)   ( 67 )  2011

    J-GLOBAL

  • 橋の構造を題材とした初等国語科目および総合科目での教育実践

    田中岳, 佐藤靖彦, 末武義崇

    土木学会北海道支部論文報告集(CD-ROM)   ( 67 )  2011

    J-GLOBAL

  • 凍結融解試験の温度履歴がモルタルの引張特性に及ぼす影響

    橋本勝文, 佐藤靖彦, 横田弘, 三浦泰人

    土木学会北海道支部論文報告集(CD-ROM)   ( 67 )  2011

    J-GLOBAL

  • CFRPストランドシートおよび高強度PPによるRC梁のせん断補強に関する実験

    荒添正棋, 小林朗, 高橋義裕, 佐藤靖彦

    土木学会年次学術講演会講演概要集(CD-ROM)   66th  2011

    J-GLOBAL

  • 凍害環境下における凍結防止剤成分の浸透に伴う水和生成相の変化

    橋本勝文, 横田弘, 杉山隆文, 佐藤靖彦

    セメント技術大会講演要旨(CD-ROM)   65th  2011

    J-GLOBAL

  • 温度履歴の異なる凍結融解試験によるモルタルの引張特性評価

    橋本勝文, 横田弘, 佐藤靖彦, 三浦泰人

    コンクリート工学年次論文集   33 ( 1 ) 929-934  2011  [Refereed]

    Rapid communication, short report, research note, etc. (scientific journal)  

  • INFLUENCE OF FROST DAMAGE WITH DEICING AGENTS ON HYDRATION PRODUCTS AND TENSILE SOFTENING BAHAVIOR

    HASHIMOTO Katsufumi, YOKOTA Hiroshi, SATO Yasuhiko, SUGIYAMA Takafumi

    Cement Science and Concrete Technology   65 ( 1 ) 400 - 405  2011

     View Summary

    Frost damage, which is the deterioration due to freeze and thaw of pore solution is causes scaling, pop-out and cracks on surface of concrete members, is an important issue in the durability of concrete structures in cold regions. Deicing agents are sprayed in order to prevent frost damage. By contrast, it has been reported that chlorides of deicing agents accelerate the deterioration due to frost damage under freeze-thaw environment. It is generally known that phase changes of hydration products, such as formation of friedel's salt and ettringite, occur due to penetration of chloride ion. Ettringite formation leads volume expansion and cracks. Since the acceleration of frost damage due to chlorides penetration, the use of deicing agents which is not containing chloride ions, such as potassium acetate and calcium-magnesium acetate, has been proposing. However, it has not been shown that chemical alteration due to penetration of deicing agents influence on increase of strain and decrease of structural characteristic value with frost damage under freeze-thaw environment. Therefore, this study aimed to investigate the influence of deicing agents under freeze-thaw environment on 1)progress of frost damage, 2)phase changes of hydration products and 3)decrease of structural characteristic value. As the results, 1)penetration of deicing agents containing chloride ions influenced on the strain hysteresis and resulted in the increase of residual strain and water absorbing ratio, 2)ettringite formation with displacement and dissolution of monosulfate hydrates was a contributory factor for frost damage acceleration and 3)chemical alteration and increase of residual strain due to penetration of chlorides led decrease of tensile strength, elastic modulus and fractural energy.

    DOI CiNii

  • 橋の構造を題材とした初等国語科目および総合科目での教育実践とその効果 : 感想文とビデオ分析のなかから(【一般A-11】初等・中等教育(2),一般研究発表【A】,発表要旨)

    田中 岳, 佐藤 靖彦, 末武 義崇

    日本教育学会大會研究発表要項   70   262 - 263  2011

    DOI CiNii

  • Application Example of Nonlinear Analysis in the Field of Concrete Structures

    SATO Yasuhiko

    耐火物 = Refractories   62 ( 9 ) 521 - 526  2010.09

    CiNii

  • Asia-Pacific Conference on FRP in Structures 2009

    佐藤 靖彦, 小林 朗

    コンクリート工学 = Concrete journal   48 ( 6 ) 47 - 48  2010.06

    CiNii

  • CFRPストランドシートで補強されたRC梁の疲労特性について

    葛西隼平, 橋田直樹, 佐藤靖彦, 小林朗, 高橋義裕

    土木学会北海道支部論文報告集(CD-ROM)   ( 66 )  2010

    J-GLOBAL

  • 低温下におけるモルタルの強度と変形について

    大河内孝彦, 佐藤靖彦

    土木学会北海道支部論文報告集(CD-ROM)   ( 66 )  2010

    J-GLOBAL

  • 凍結融解作用を受けるコンクリート中の鉄筋の挙動

    三河智将, 佐藤靖彦

    土木学会北海道支部論文報告集(CD-ROM)   ( 66 )  2010

    J-GLOBAL

  • 樹脂接合された鋼-自己充填型鋼繊維補強モルタル合成部材の曲げ性状

    山崎大輔, 佐藤靖彦, 塩永亮介

    土木学会北海道支部論文報告集(CD-ROM)   ( 66 )  2010

    J-GLOBAL

  • NaCl溶液に浸漬したモルタルの引張軟化特性のモデル化

    三浦泰人, 佐藤靖彦

    土木学会年次学術講演会講演概要集(CD-ROM)   65th  2010

    J-GLOBAL

  • Asia-Pacific Conference on FRP in Structures 2009の参加報告

    佐藤 靖彦, 小林 朗

    コンクリート工学   48 ( 6 ) 6_47 - 6_48  2010

    CiNii

  • STUDY ON AXIAL TENSILE BEHABIOR OF HIGH PERFORMANCE FIBER REINFORCED MORTAR WITH REINFORCING BAR

    SHIONAGA Ryosuke, SATO Yasuhiko, C. WALRAVEN Joost

    Journal of Japan Society of Civil Engineers, Ser. E1 (Pavement Engineering)   66 ( 4 ) 366 - 379  2010

     View Summary

    This Paper presents experimental and numerical results on axial tensile tests of prism members with HPFRM (High Performance Fiber Reinforced Mortar) and conventional reinforcing bar. With increasing fiber content in the HPFRM, the tension stiffening effect was improved as well as cracks being distributed with finer crack width. In addition the orientation of the fibers affected both the tension stiffening and the crack distribution. To evaluate these structural behaviors the analytical simulation using 2D Rigid Body Spring Model was applied with some improvements on the material constitutive law for unique characteristics on the HPFRM.

    DOI CiNii

  • FRACTURE MECHANISM AND PREDICTION OF DEFORMATION OF MORTAR UNDER TIME-DEPENDENT LOADS BY MESO-SCALE ANALYSIS

    MATSUMOTO Koji, SATO Yasuhiko, UEDA Tamon

    Journal of Japan Society of Civil Engineers, Ser. E1 (Pavement Engineering)   66 ( 4 ) 380 - 398  2010

     View Summary

    Time-dependent constitutive law of Rigid-Body Spring Model (RBSM) was developed by separating mortar deformation into four components based on material information from micro to meso scale. In addition, the analysis could track residual strength up to the failure under creep and fatigue loading by installing a new method for determining failure state for load-controlled analysis. The analytical model could simulate mortar behavior under monotonic, creep and fatigue loading in terms of change in strength, stress-strain-time and S-N relationship. Furthermore, fracture mechanism of mortar under creep and fatigue loading was numerically explained. That is, failure happens when the material strength becomes less than the applied stress as a result of crack propagation with stress release-redistribution due to relaxation or unloading-reloading.

    DOI CiNii

  • Modeling of tension stiffening effect on high performance fiber reinforced mortar

    Shionaga Ryosuke, Sato Yasuhiko

    Kozo Kogaku Ronbunshu. A   56   938 - 946  2010

     View Summary

    This paper represents a tension stiffening effect on a High Performance Fiber Reinforced Mortar (HPFRM), which has a compressive strength of 130 N/mm2 and high tensile ductility by the addition of short steel fibers. Uni-axial tensile tests on the reinforced HPFRM with various fiber content and fiber orientation were conducted. On basis of the experimental results and the analytical simulations using Rigid Body Spring Model (RBSM), a simplified equation to determine the tension stiffening effect on the HPFRM was proposed. The accuracy of the model was verified through simulations with non-liner FEM analyses on reinforced HPFRM members.

    DOI CiNii

  • Evaluation of Tensile Softening Behavior of Cement-paste and Mortar Deteriorated by NaCl Solution

    MIURA Taito, SATO Yasuhiko

    Concrete Research and Technology   21 ( 3 ) 77 - 86  2010

     View Summary

    In this study, cement paste and mortar specimens were immersed in NaCl solution for 2 months. After that three points bending test of the specimens and chemical analyses were conducted so as to determine tension softening curves, which can be applicable to meso-scale analysis, from load-displacement curves using a back analysis and to clarify how amount of cement hydrates affects the tension softening behavior. It was found, as a result, that tensile strength, Young's modulus and fracture energy of mortar specimens become smaller as the amount of cement hydrate CH decreases. Furthermore tension softening model which can consider the change in amount of cement hydrates was proposed.

    DOI CiNii J-GLOBAL

  • A study on material deterioration of RC beam components due to frost damage and their structural performance

    林田 宏, 佐藤 靖彦, 上田 多門

    Monthly report   ( 679 ) 11 - 18  2009.12

    CiNii

  • 水中におけるコンクリートの疲労特性について

    小田光葉, 佐藤靖彦

    土木学会北海道支部論文報告集(CD-ROM)   ( 65 )  2009

    J-GLOBAL

  • RCはり部材の凍結融解劣化性状に関する実験

    針谷龍史, 佐藤靖彦, 上田多門, 林田宏

    土木学会北海道支部論文報告集(CD-ROM)   ( 65 )  2009

    J-GLOBAL

  • 酸性抗廃水によるセメントペーストの化学的劣化に関する一実験

    藤井謙一, 佐藤靖彦

    土木学会北海道支部論文報告集(CD-ROM)   ( 65 )  2009

    J-GLOBAL

  • 登別温泉水に浸漬したモルタルの化学・力学的特性に関する一実験

    三浦泰人, 佐藤靖彦

    土木学会北海道支部論文報告集(CD-ROM)   ( 65 )  2009

    J-GLOBAL

  • CFRPストランドシート補強RCはりの静的挙動に関する一考察

    橋田直樹, 佐藤靖彦

    土木学会北海道支部論文報告集(CD-ROM)   ( 65 )  2009

    J-GLOBAL

  • CFRPストランドシートの剥離耐力向上に関する実験的研究

    高橋義裕, 佐藤靖彦, 小林朗

    土木学会年次学術講演会講演概要集(CD-ROM)   64th ( Disk 2 )  2009

    J-GLOBAL

  • FRPストランドシートで曲げ補強したRCはりの耐荷性状関する実験的検討

    小林朗, 高橋義裕, 佐藤靖彦

    土木学会年次学術講演会講演概要集(CD-ROM)   64th ( Disk 2 )  2009

    J-GLOBAL

  • Analytical study on neutralization of concrete taking acid rain and crack into account

    KISHIMOTO Yoshihiko, SATO Yasuhiko, HOKOI Shuichi

    Proceedings of the Japan Concrete Institute   30 ( 1 ) 669 - 674  2008

    CiNii

  • 各種補強材により下面補強されたRCはりの曲げ耐力に関する実験的研究

    高橋義裕, 佐藤靖彦, 小林朗

    土木学会年次学術講演会講演概要集(CD-ROM)   63rd ( Disk 2 )  2008

    J-GLOBAL

  • Utilization of nonlinear finite element analysis method

    NAKAMURA Hikaru, KANEKO Yoshio, SATO Yasuhiko, SATO Yuichi, SAITO Shigehiko, TSUTSUMI Tadahiko

    Proceedings of the Japan Concrete Institute   30 ( 1 ) 33 - 40  2008

     View Summary

    本研究委員会は,非線形有限要素解析法の信頼性の向上と利用の拡大を目的に調査・研究活動を行った。具体的には,非線形有限要素法の基礎・基本を手引書の形で整理した上で,その手引書に基づく実解析を通じ,解析上の留意点を分かりやすくまとめた。さらには,非線形有限要素法を活用した検討が,実構造物の施工性の改善や安全性の向上に大きく貢献できる事例を提示した。

    CiNii

  • Bending behavior on reinforced thin slabs using high strength fiber reinforced mortar

    SHIONAGA Ryosuke, SATO Yasuhiko, WALRAVEN Joost C.

    Proceedings of the Japan Concrete Institute   30 ( 1 ) 309 - 314  2008

     View Summary

    100N/mm^2以上の圧縮強度を有し,鋼繊維を混入した高強度繊維補強モルタルを適用した鉄筋コンクリート部材の変形性能および耐荷性能を把握するため,薄肉の試験体による曲げ載荷試験を実施した。実験のパラメータとして,鉄筋量および鋼繊維の混入率,種類,配向性を変えることで,それらが部材の曲げ靭性やひび割れ性状に与える影響を定量的に把握した。さらに,直接引張試験より得られた引張応力下の力学モデルを適用した非線形EEM解析による検証解析により,鉄筋を有する高強度繊維補強モルタル部材の耐荷挙動のシミュレーションを可能とした。

    CiNii J-GLOBAL

  • Damage evaluation of mortar under fatigue loading by RBSM

    松本 浩嗣, 佐藤 靖彦, 上田 多門

    Proceedings of the Japan Concrete Institute   30 ( 3 ) 97 - 102  2008

     View Summary

    著者が提案している剛体バネモデルの時間依存構成モデルを改良し,モルタルの時間依存破壊シミュレーションを高ひずみ速度域に拡張した。これにより,ひずみ速度の増加がモルタルの強度増進に与える影響,さらには,実際の疲労載荷速度下におけるモルタルの破壊過程が再現可能となり,実験結果を良好に表すことができた。また,残存強度変化を調べることで,疲労荷重下におけるモルタルの累積損傷度の評価を行った。モルタルの累積損傷は載荷回数に対して線形ではなく,ある時点を境に急激に増加することを確認した。

    CiNii

  • Failure behavior of RC beams strengthened by carbon fiber plates

    佐藤 靖彦, 小林 朗, 高橋 義裕

    Proceedings of the Japan Concrete Institute   30 ( 3 ) 1519 - 1524  2008

     View Summary

    炭素繊維プレートにより曲げ補強された鉄筋コンクリートはりの破壊性状と耐力に関する実験的研究を行った。実験変数は,接着枚数(1枚,2枚,3枚),接着の仕方(積層と並列),接着長を変えることによる端部でのプレート剛性の低減の有無である。プレートを積層接着すると付着応力が増加し,はく離破壊が早期に発生すること,プレートを2もしくは3枚並列に接着すると,積層する場合よりも耐力が増加するものの,プレートを1枚だけ接着した場合の耐力を下回る可能性があることを明らかにした。また,はく離破壊を支配する端部の付着強度は,剛性が大きいほど増加するが,上限値が存在する可能性を示した。

    CiNii

  • Study on material properties of FRP strand sheets and flexural strengthening effect of FRP strand sheets

    小林 朗, 佐藤 靖彦, 高橋 義裕, 立石 晶洋

    Proceedings of the Japan Concrete Institute   30 ( 3 ) 1561 - 1566  2008

     View Summary

    連続繊維シート接着工法の施工性の改善やFRPプレート接着工法の補強性能の改善を日的として連続繊維ストランド1本ずつに樹脂を含浸・硬化させたFRPストランドシートを新たに開発した。このFRPストランドシートの引張試験,継手試験,付着強度試験を行ない材料特性を評価した。さらにFRPストランドシートで補強したRCはりの曲げ載荷試験を行いその補強効果について検討した。FRPストランドシートを接着することでRCはりの曲げ剛性および曲げ耐力は増加し,同種の連続繊維を用いた連続繊維シートに比べ剥離荷重が高くなった。FRPストランドシートの引張剛性の違いによって,破壊モードに違いが見られた。

    CiNii

  • 剛体バネモデルを用いたモルタルの時間依存破壊解析

    松本浩嗣, 佐藤靖彦, 上田多門

    土木学会北海道支部論文報告集(CD-ROM)   ( 63 )  2007

    J-GLOBAL

  • Experimental sturdy on shear capacity of RC beams strengthened by FRP post-embedded method

    小林 朗, 佐藤 靖彦, 高橋 義裕

    Proceedings of the Japan Concrete Institute   29 ( 3 ) 1585 - 1590  2007

    CiNii

  • Basic experiment on concrete deterioration caused by fatigue and freezing-thawing action

    今野 克幸, 佐藤 靖彦

    Proceedings of the Japan Concrete Institute   29 ( 1 ) 903 - 908  2007

     View Summary

    本研究では,疲労荷重がコンクリートの耐凍害性に与える影響について検討するために,疲労荷重と凍結融解作用の組合せ方を変化させた実験を行った。すなわち,初期状態を軽微な乾燥状態としたコンクリートを対象とした,疲労と凍結融解を交互に作用させた複合劣化試験を行い,それら作用の順序や回数がコンクリートの相対動弾性係数と静弾性係数の推移及び残存強度に及ぼす影響を検討した

    CiNii

  • Influence of water permeability on neutralization process in concrete

    岸本 嘉彦, 佐藤 靖彦, 中村 麻里亜, 鉾井 修一

    Proceedings of the Japan Concrete Institute   29 ( 1 ) 951 - 956  2007

     View Summary

    本研究は,コンクリート構造物の上面近傍に透水性の大きい層が存在することに着目し,上面近傍の透水性の差異が中性化の進行に及ぼす影響を明らかにすることを目的とする。まず,円柱試験体の上面近傍の透水係数を測定した。次に,材料内の熱水分移動と化学物質移動を考慮した中性化反応モデルを提案した。この解析モデルを用い,測定した透水係数の差異が,酸性雨に曝される条件下の中性化の進行に及ぼす影響を検討した。

    CiNii

  • Analysis of deformational behavior of mortar under freezing and thawing

    大岩 祐司, 佐藤 靖彦, 上田 多門, 松本 浩嗣

    Proceedings of the Japan Concrete Institute   29 ( 1 ) 1179 - 1184  2007

     View Summary

    本研究において,剛体バネモデル解析法を用いた,モルタルの凍結融解時の変形挙動の解析方法を開発した。その手法は,固相,液相,気相の3相を考えた熱水分同時移動方程式に基づきモルタル内の温度,水分量,氷の量(含氷率)を求め,得られた温度と氷の膨張によるひずみを初期ひずみとして剛体バネモデル解析法に引き渡し,モルタルの凍結及び融解時の変形挙動を求めるものである。

    CiNii

  • Time-dependent fracture simulation of mortar under sustained and cyclic loading by RBSM

    MATSUMOTO Koji, SATO Yasuhiko, UEDA Tamon

    Proceedings of the Japan Concrete Institute   29 ( 3 ) 811 - 816  2007

     View Summary

    離散解析手法のひとつである剛体バネモデルの時間依存型構成則を構築し,持続および繰り返し荷重を受けるモルタルの破壊解析を行った。連結バネの時間依存モデルには,4成分系力学モデルを採用し,かつ,荷重制御解析における新しい破壊判定方法を用いることにより,破壊までの載荷時間及び終局ひずみの評価が可能となった。解析では,時間の経過に伴う変形挙動を表現することに成功した。また,連結バネの応力-ひずみ挙動を調べ,モルタルの時間依存破壊メカニズムに対する検証を行った。

    CiNii

  • Tensile behavior of high strength fiber reinforced mortar with reinforcing bars

    SHIONAGA Ryosuke, SATO Yasuhiko, WALRAVEN Joost C.

    Proceedings of the Japan Concrete Institute   29 ( 3 ) 1459 - 1464  2007

     View Summary

    現在,多種の高性能繊維補強セメント系複合材の開発が国内外で進められている中,材料単体の引張性能の実験的評価は多くなされているものの,鉄筋コンクリート部材としての引張性能の把握は十分になされていない。本論文では,鉄筋補強された高強度繊維補強モルタル部材の一軸引張試験結果より,銅繊維の混入量が多いほど,鋼繊維のアスペクト比が高いほど部材の引張剛性や耐荷力が向上することを確認した。さらに試験体製作時に違えた鋼繊維の配向性の差によってもこれら力学的特性に大きな差が生じることも示された。

    CiNii J-GLOBAL

  • Influence of CFRP sheet length and U-jacket on flexural behavior of RC beams

    TAKAHASHI Yoshihiro, SATO Yasuhiko

    Proceedings of the Japan Concrete Institute   29 ( 3 ) 1477 - 1482  2007

     View Summary

    RCはり下面に曲げ補強として2層のCFRPシートを貼付し(1層目のコンクリートに直接貼付されるシート長を変化させ,2層目のシート長は154mmで一定),さらに剥離防止のためのU字補強量を変化させたRCはりに静的二点対称荷重を作用させた載荷試験を行った。本研究では,1層目のCFRPのシート長を64cm,108cm,154cmと,シートの剥離制御を目的とし下面からウェブに渡るU字状の巻上げ補強(以下「U字補強」と呼ぶ)量を0,4,8,12,16本と変化させた。はりの最大荷重は,U字補強16本の場合,1層目シート長によらずほぼ同じ値を示した。また,U字補強量増加により終局変位が増加した。

    CiNii J-GLOBAL

  • 剛体バネモデルによるモルタルの時間依存解析

    松本浩嗣, 上田多門, 佐藤靖彦

    土木学会北海道支部論文報告集(CD-ROM)   ( 62 )  2006

    J-GLOBAL

  • Analytical investigation of concrete made of recycled fine aggregate

    今野 克幸, 佐藤 靖彦

    Proceedings of the Japan Concrete Institute   28 ( 1 ) 1469 - 1474  2006

     View Summary

    再生細骨材を用いたコンクリートの強度低下の要因について,数値解析による検討結果を示した。また,数値解析に用いる主な構成則として再生細骨材を用いたモルタルの最大せん断応力および粗骨材と再生細骨材を用いたモルタルの界面の付着強度を実験により求めた。

    CiNii

  • Shear capacity of ultra high performance fiber reinforced concrete beam

    PANSUK Withit, SATO Yasuhiko, UEDA Tamon, SHIONAGA Ryosuke

    Proceedings of the Japan Concrete Institute   28 ( 2 ) 1405 - 1410  2006

    CiNii

  • FRPグリッドにより補強されたRCはりのせん断性状

    小林朗, 佐藤靖彦, 上田多門, 岩崎健

    土木学会北海道支部論文報告集(CD-ROM)   ( 61 )  2005

    J-GLOBAL

  • 疲労荷重下でのFRPシートの付着劣化について

    古内仁, 齋藤佑樹, 上田多門, 佐藤靖彦, DAI Jianguo

    土木学会北海道支部論文報告集(CD-ROM)   ( 61 )  2005

    J-GLOBAL

  • 鉄筋の付着特性に及ぼす鉄筋本数の影響

    大岩祐司, 上田多門, 佐藤靖彦, HASAN Muttaqin

    土木学会北海道支部論文報告集(CD-ROM)   ( 61 )  2005

    J-GLOBAL

  • 下面曲げ補強RC梁に対する貼付CFRPシート幅の影響について

    高橋義裕, 佐藤靖彦

    土木学会北海道支部論文報告集(CD-ROM)   ( 61 )  2005

    J-GLOBAL

  • 損傷を有するコンクリートの凍結融解作用後の圧縮強度

    福島佳志美, 佐藤靖彦, 上田多門, HASAN Muttaqin

    土木学会北海道支部論文報告集(CD-ROM)   ( 61 )  2005

    J-GLOBAL

  • CFRPシート曲げ補強RC梁の曲げ挙動に及ぼすシート幅の影響に関する実験的研究

    高橋義裕, 佐藤靖彦

    土木学会年次学術講演会講演概要集(CD-ROM)   60th ( Disk 2 )  2005

    J-GLOBAL

  • 非線形解析によるコンクリート構造物の性能照査-手順と検証例・照査例-

    中村光, 佐藤靖彦, 斉藤成彦, 松尾豊史, 矢部明人, 渡辺忠朋, 別府万寿博, 小原孝之, 森田修二, 金子雄一, 川上誠, 幸左賢二, 山谷敦, 余国雄, 高橋良輔, 高木康宏, 田所敏弥, 田中浩一

    コンクリート技術シリーズ   ( 66 )  2005

    J-GLOBAL

  • CFRPシートで曲げ補強されたRCはりの耐力及び変形に関する実験的研究

    高橋 義裕, 佐藤 靖彦

    コンクリート工学年次論文集   27 ( 2 ) 1423 - 1428  2005

     View Summary

    鉄筋コンクリート梁下面に曲げ補強として貼付するCFRPシート幅の変化とシート層数との関係に着目し静的二点対称荷重を作用させた載荷試験を行った。本研究では,CFRPのシート幅(85mmと170mm)及び層数(1層~4層)と変化させ,さらにシートの剥離制御を目的とし下面からウェブに渡るU字状の巻上げ補強(以下U字補強と呼ぶ)を行った。はりの最大荷重は,シート幅85mmで4層貼付した場合とシート幅170mmで2層の場合とでは,ほぼ同じ値を示した。しかし,U字補強したシート幅85mm4層と幅170mm2層とではシート幅170mm2層の方が最大荷重は約17%の増加であった。

    CiNii

  • Three-dimensional mesoscopic simulation of concrete under biaxial stress condition by RBSM

    NAGAI Kohei, SATO Yasuhiko, UEDA Tamon

    Proceedings of the Japan Concrete Institute   27 ( 2 ) 175 - 180  2005

    CiNii

  • Influence of Top Flange to Shear Resisting Mechanism of Reinforced Concrete T-Beams

    PANSUK Withit, SATO Yasuhiko, TAKAHASHI Ryosuke, UEDA Tamon

    Proceedings of the Japan Concrete Institute   27 ( 2 ) 859 - 864  2005

    CiNii

  • FAILURE CRITERION FOR FRP ROD UNDER LOCALIZED STRESS

    KONNO Katsuyuki, UEDA Tamon, SATO Yasuhiko, OBARA Takayuki

    土木学会論文集 = Proceedings of JSCE   ( 774 ) 83 - 98  2004.11

    DOI CiNii

  • 再生粗骨材を用いたコンクリートの凍結融解抵抗性

    佐藤 靖彦, 佐々木 慎一, 奥山 英俊, 今野 克幸

    コンクリート工学年次論文集   26 ( 1 ) 1503 - 1508  2004

     View Summary

    再生粗骨材を用いたコンクリートの凍結融解抵抗性を実験的に明らかにした。すなわち,原コンクリートがnon-AEコンクリートであっても再生コンクリートの平均吸水率を3%以下とすることで高い凍結融解抵抗性を確保できること,また,大きな収縮ひずみ(本実験では750μ以上)を経験した後の凍結融解抵抗性は著しく低下することを明らかにした。

    CiNii

  • 横方向の緊張力を導入した角柱供試体の終局耐力に関する解析的検討

    あべ松 隆太, 上田 多門, 佐藤 靖彦, 中井 裕司

    コンクリート工学年次論文集   26 ( 2 ) 271 - 276  2004

     View Summary

    本研究室で開発された3次元非線形有限要素プログラムを使用し,拘束筋として緊張されたPC鋼材を用いた角柱供試体の一軸圧縮試験を解析し十分な解析精度を得ることができた。そのプログラムを使用し補強筋比・緊張力量をパラメーターとした解析を行い,それらを変数とし終局耐力との関係を明らかにした。

    CiNii

  • せん断補強筋の定着不良がRCはりのせん断耐力に及ぼす影響

    前川 宏一, 中村 光, 佐藤 靖彦, TOONGOENTHONG Kukrit

    コンクリート工学年次論文集   26 ( 2 ) 973 - 978  2004

     View Summary

    せん断補強鉄筋の定着不良がRCはりのせん断抵抗機構に及ぼす影響を検討する目的で,せん断補強鉄筋の定着フック及び端部近傍の付着を除去したはりを製作し,せん断耐力の低下と破壊モードを実験的に検証した。せん断補強鉄筋によるせん断負担分がコンクリートの負担分と同程度に高く,トラス機構が顕著となるせん断スパン比に対しては,定着不良がトラス機構の保持を困難なものにする場合があることを確認した。さらに,せん断補強鉄筋の有効性は,鉄筋端部の付着劣化域を簡便に考慮した非線形ひび割れ解析で凡そ評価が可能であることを示した。

    CiNii J-GLOBAL

  • 初期荷重を受けCFRPシート補強されたRC梁の曲げ挙動

    高橋 義裕, 佐藤 靖彦

    コンクリート工学年次論文集   26 ( 2 ) 1699 - 1704  2004

     View Summary

    初期荷重をRCはりに作用させ,ある程度の損傷をRCはりに与え後にCFRPシートを下面に貼付し,再度静的曲げ載荷試験を行った。本研究では,CFRPのシート層数を変化させ(1層~3層),さらにシートの貼付方法としてはコンクリートとシートとの間に緩衝材を塗布した場合,さらにシートの剥離制御を目的とし下面からウェブ全高さに渡り5cm幅シートによりU字状に巻き上げたU字補強を行った場合について検討した。はりの最大耐力は,全てにおいて緩衝材を塗布し,さらにU字補強を行った場合が最大値を示した。また,シート層数の増加割合ほど耐力は増加しなかった。

    CiNii

  • Analytical Study on Influence of Mortar-Aggregate Interface Character on Concrete Strength by RBSM

    NAGAI Kohei, SATO Yasuhiko, UEDA Tamon

    Proceedings of the Japan Concrete Institute   26 ( 2 ) 151 - 156  2004

    CiNii

  • Dowel Effects on Interface Shear Bond Force Transfer in Concrete Beams Strenthened with FRP Sheets

    DAI Jianguo, UEDA Tamon, SATO Yasuhiko

    Proceedings of the Japan Concrete Institute   26 ( 2 ) 883 - 888  2004

    CiNii

  • Influence of Top Flange to Shear Capacity of Reinforced Concrete T-Beams

    PANSUK Withit, SATO Yasuhiko, TAKAHASHI Ryosuke, UEDA Tamon

    Proceedings of the Japan Concrete Institute   26 ( 2 ) 991 - 996  2004

    CiNii

  • SHEAR TRANSFERRING MECHANISM ALONG DIAGONAL CRACKS AND DIAGONAL TENSION FAILURE BEHAVIOR OF RC MEMBERS

    TADOKORO Toshiya, SATO Yasuhiko, UEDA Tamon

    土木学会論文集   ( 739 ) 195 - 211  2003.08

    DOI CiNii J-GLOBAL

  • 1257 MODE I FRACTURE BEHAVIORS OF FRP-CONCRETE INTERFACES

    DAI Jianguo, UEDA Tamon, HASAN Muttaqin, SATO Yasuhiko

    Proceedings of the Japan Concrete Institute   25 ( 1 ) 1577 - 1582  2003.07

     View Summary

    The Mode II interlaminar fracture tests of hybrid composites with non-woven carbon tissue (NWCT) were carried out using the end-notched-flexure (ENF) specimen. The hybrid composites were made by interleaving NWCT prepreg between CFRP layers. CFRP specimen [0<SUB>24</SUB>] as well as hybird specimen [0<SUB>12</SUB>/T/0<SUB>12</SUB>] were prepared to compare the Model II interlaminar fracture tough-ness. Here, the symbol "/T/" means that NWCT prepreg is located at a 0/0 mid-plane of the hybrid specimen. Three kinds of interlaminar cracks which have different positions in the NWCT layer were introduced to the hybrid specimen. It was found that the NWCT layer has the short fiber bridging effect due to in-plane random short carbon fibers and increases the interlaminar fracture toughness of laminated composites. The fracture surfaces and side-sections of the hybird specimens were observed with an optical microscope and a scanning elelctron microscope, and the failure mechanism was discussed.

    CiNii

  • 資源の活用 寒冷地における再生コンクリートの実用化に向けた試み

    佐藤 靖彦, 田口 史雄, 桂 修

    コンクリートテクノ   22 ( 3 ) 27 - 30  2003.03

    CiNii

  • 付着モルタルが再生コンクリートの力学特性に及ぼす影響の解析的評価

    奥山 英俊, 長井 宏平, 佐藤 靖彦

    コンクリート工学年次論文集   25 ( 1 ) 1235 - 1240  2003

     View Summary

    本研究では,再生粗骨材に付着するモルタルが再生コンクリートの力学特性に及ぼす影響を,付着モルタル及び界面の強度特性の差異を考慮できる剛体バネモデル(RBSM)により検討した。その結果,付着モルタルと原骨材間の界面強度(旧界面)及び付着モルタルの強度が大きければ圧縮強度は大きくなるが,モルタル付着率が小さく,旧界面と新モルタルと旧モルタルとの界面(新界面)との距離が狭いと,ばらつきが大きくなることが明らかとなった。

    CiNii

  • 持続荷重および繰返し荷重を受けるコンクリートの変形性状に関する検討

    立石 晶洋, 佐藤 靖彦, 角田 與史雄

    コンクリート工学年次論文集   25 ( 2 ) 1123 - 1128  2003

     View Summary

    持続および繰返し荷重を受けるコンクリートの変形性状を明らかにするためにコンクリート平板の一軸圧縮試験を行った。各種荷重による変形性状の差異を比較する指標として,除荷時の弾性係数と残留ひずみを軸ひずみおよび軸直角ひずみとの関係に着目した。その結果,軸ひずみは作用荷重の影響を大きく受けること,コンクリートの損傷過程は,いずれの荷重に対しても,軸直角ひずみを指標として一義的に表せることを明らかにした。

    CiNii

  • 初期荷重を受けたRCはりに対するCFRP補強について

    高橋 義裕, 佐藤 靖彦

    コンクリート工学年次論文集   25 ( 2 ) 1873 - 1878  2003

     View Summary

    初期荷重をRCはりに作用させ,ある程度の損傷をRCはりに与え後にCFRPシートを下面に貼付し,再度静的曲げ載荷試験を行った。本研究では,CFRPのシート層数を変化させ(1層~3層),さらにシートの貼付方法としてはコンクリートとシートとのに緩衝材を塗布しその有無による影響等について実験的に検討した。初期荷重による損傷をうけたはりの最大耐力は,初期荷重を受けなかったはりの最大耐力を上回ることはなかった。また,シート層数が3層で緩衝材を塗布した場合には初期荷重によるシートひずみへの影響は殆ど見られなかった。

    CiNii J-GLOBAL

  • 講座 非線形解析の特徴と留意点

    佐藤 靖彦, 中村 光

    プレストレスト・コンクリ-ト   45 ( 1 ) 121 - 130  2003.01

    CiNii

  • SHEAR DEFORMATION OF REINFORCED CONCRETE BEAM

    UEDA Tamon, SATO Yasuhiko, ITO Tsunemasa, NISHIZONO Katsuhide

    Doboku Gakkai Ronbunshu   711   205 - 215  2002.08

     View Summary

    This paper presents the experimental results on shear deformation of concrete beams with shear reinforcement, which was measured by laser speckle method. The results indicate that besides flexural deformation the significant amount of shear deformation occurred after shear cracking, which was caused by the localized shear deformation along shear cracks. Based on the experimental results, a rather simple mechanical model for prediction of the deformation is proposed. The model consists of a truss model that calculates the shear deformation and a modified Branson's model with the tension shift concept to calculate the flexural deformation. The model can predict the experimental results well.

    DOI CiNii

  • A simulation of shear behavior of steel-concrete composite slab by 3D nonlinear FEM.

    高橋良輔, 佐藤靖彦, 上田多門

    構造工学論文集 A   48A ( 3 )  2002

    J-GLOBAL

  • 骨材の平均吸水率に着目した再生コンクリートの特性評価

    今野 克幸, 松村 宇, 佐藤 靖彦, 田口 史雄

    コンクリート工学年次論文集   24 ( 1 ) 1245 - 1250  2002

     View Summary

    本研究ではコンクリートを作製する際に用いた粗骨材として普通骨材,再生骨材,それらを混合したものを用いており(以降,それらを総称して使用骨材と呼ぶ),使用骨材の平均的な吸水率を変化させ,再生コンクリートの圧縮強度,凍結融解抵抗性,乾燥収縮特性を明らかにする目的で実験を行った.再生骨材は3種類用意しており,使用骨材の平均的な吸水率が等しくなるよう普通骨材と再生骨材の混合割合を調整した供試体も作製した.使用骨材の平均的な吸水率に着目した結果,平均吸水率がコンクリートの圧縮強度と凍結融解抵抗性に与える影響は見られなかったが,乾燥収縮ひずみの大きさに与える影響は顕著であった.

    CiNii

  • 3次元非線形FEM解析による鉄筋コンクリート部材の純ねじり耐力に関する一考察

    高橋 良輔, 佐藤 靖彦, 上田 多門

    コンクリート工学年次論文集   24 ( 2 ) 67 - 72  2002

     View Summary

    本研究では,過去に提案されている構成モデルを組み合わせた3次元非線形有限要素プログラムを開発し,鉄筋コンクリート棒部材の純ねじり解析を行い,本プログラムの検証とせん断流に着目した考察を行った。その結果,本プログラムによる解析結果は,概ね実験値に一致し,また,せん断流の幅は鉄筋比によって影響を受けないこと,中空断面鉄筋コンクリート棒部材において,せん断流路幅分の厚さがあればそのねじり耐力は中実断面の場合とほぼ同じに取り扱えることが解析的に確認された。

    CiNii

  • 緩衝材を用いた炭素繊維シート補強RCはりの曲げ挙動

    佐藤 靖彦, 伊藤 智之, 小牧 秀之, 前田 敏也

    コンクリート工学年次論文集   24 ( 2 ) 1375 - 1380  2002

     View Summary

    剥離抑制を目的として弾性係数が小さい緩衝材を用いた炭素繊維シート補強鉄筋コンクリートはりの静的及び疲労載荷試験を行った。静的試験結果より,接着端部から約300mmの区間における炭素繊維シートの平均付着応力の最大値は緩衝材を用いた方が大きく,その結果,剥離が抑制され耐力が増加すること,また,200万回の繰返し荷重を受けた後であっても,緩衝材を用いない場合と同等かそれ以上の残存耐力を有していることを明らかにした。

    CiNii

  • 炭素繊維で曲げ補強したRCはりの耐力及び変形に関する実験的研究

    高橋 義裕, 佐藤 靖彦

    コンクリート工学年次論文集   24 ( 2 ) 1393 - 1398  2002

     View Summary

    RCはりの下面に炭素繊維(CFRP)シートを貼付し曲げ試験を行った。実験供試体は全部で10体で,CFRPのシート層数をパラメータとし,シートの貼付方法としてコンクリートとシートとの間の緩衝材の有無とU字巻き上げ補強の有無について実験的に検討した。緩衝材を設けた供試体では,その最大荷重は緩衝材を設けなかった供試体に対し最大で46%増加した。また,供試体にU字巻き上げ補強を併用すことにより,終局変位の増加と若干の最大荷重の増加が確認できた。

    CiNii

  • Tensile Stress-Crack Width Model for Plain Concrete Damaged by Freezing and Thawing Action

    HASAN Muttaqin, NAGAI Kohei, SATO Yasuhiko, UEDA Tamon

    Proceedings of the Japan Concrete Institute   24 ( 2 ) 109 - 114  2002

    CiNii

  • Numerical Simulation of Fracture Process of Concrete Model by Rigid Body Spring Method

    NAGAI Kouhei, SATO Yasuhiko, UEDA Tamon, KAKUTA Yoshio

    Proceedings of the Japan Concrete Institute   24 ( 2 ) 163 - 168  2002

    CiNii

  • Improving the Load Transfer and Effective Bond Length for FRP Composites Bonded to Concrete

    DAI Jianguo, SATO Yasuhiko, UEDA Tamon

    Proceedings of the Japan Concrete Institute   24 ( 2 ) 1423 - 1428  2002

    CiNii

  • Deformational Characteristics of Concrete Pier Reinforced with Carbon Fiber Flexible Reinforcement

    OKUBO Seiichiro, SATO Yasuhiko, TULADHAR Roshan, KOBAYASHI Akira

      23 ( 1 ) 853 - 858  2001.06

    CiNii

  • 3178 繰返し荷重を受けるコンクリートの変形性状について(疲労)

    佐藤 公紀, 佐藤 靖彦, 角田 與史雄

    コンクリート工学年次論文集   23 ( 3 ) 1063 - 1068  2001.06

     View Summary

    本研究において、静的および繰返しの圧縮荷重を受けるコンクリートの破壊に至るまでの変形性状を実験的に明らかにした。すなわち、破壊に至るまでの軸ひずみと体積ひずみとの関係は、荷重条件によらずほぼ等しいこと、繰返し荷重下の弾性係数の変化は全ひずみのみによって表せ得ること、塑性ひずみは載荷時間の影響を大きく受けることを明らかにすると共に、クリープひずみを用いて繰返し荷重を受けるコンクリートの塑性ひずみの算定方法を提案した。

    CiNii

  • Deformational Characteristics of Concrete Pier Reinforced with Carbon Fiber Flexible Reinforcement

    OKUBO Seiichiro, SATO Yasuhiko, TULADHAR Roshan, KOBAYASHI Akira

    Proceedings of the Japan Concrete Institute   23 ( 1 ) 853 - 858  2001.06

     View Summary

    炭素繊維フレキシブル筋(以下CFFR)をせん断補強筋として用いたコンクリート橋脚模型の一方向繰返し載荷、正負交番繰返し載荷を行い,その変形特性について実験的に検討した。CFFRは、本実験のような大変形を起こす供試体においてその効果を十分に発揮し、補強部材の変形性能を大きく向上させ得ることが明らかとなった。また繊維のひずみは折り曲げ部を超えて生ずるが、その伝達率はひずみが増加するにつれ、既往のU字型引張試験で得られた値に収束する傾向があった。

    CiNii

  • The Influence of Compression Softening to Shear Strength for RC Members

    TADOKORO Toshiya, SATO Yasuhiko, UEDA Tamon

    Proceedings of the Japan Concrete Institute   23 ( 3 ) 61 - 66  2001.06

     View Summary

    鉄筋コンクリート(以下RCと略す)部材の終局挙動を数値解析によって予測,再現するためにはコンクリートのひずみ軟化特性のモデル化が不可欠である.本研究では,破壊エネルギーの概念に基づいた圧縮・引張場における圧縮軟化モデルを2軸圧縮場に拡張し,せん断圧縮破壊するRC部材の終局挙動に及ぼす影響について検討した.その結果,せん断圧縮破壊するRC部材の耐力および終局変形は圧縮軟化特性,つまり圧縮破壊エネルギーに大きく依存すると言え,圧縮強度20(MPa)のコンクリートを用いた場合,圧縮破壊エネルギーを40(N/mm)とすると耐力,終局変形,破壊モードおよび圧壊領域を概ね推定できることが確認できた.

    CiNii

  • The Influence of Compression Softening to Shear Strength for RC Members

    TADOKORO Toshiya, SATO Yasuhiko, UEDA Tamon

      23 ( 3 ) 61 - 66  2001.06

    CiNii

  • 繰返し荷重を受けるコンクリートの変形性状について

    佐藤 公紀, 佐藤 靖彦, 角田 與史雄

    コンクリート工学年次論文報告集   23 ( 3 ) 1063 - 1068  2001.06

     View Summary

    本研究において、静的および繰返しの圧縮荷重を受けるコンクリートの破壊に至るまでの変形性状を実験的に明らかにした。すなわち、破壊に至るまでの軸ひずみと体積ひずみとの関係は、荷重条件によらずほぼ等しいこと、繰返し荷重下の弾性係数の変化は全ひずみのみによって表せ得ること、塑性ひずみは載荷時間の影響を大きく受けることを明らかにすると共に、クリープひずみを用いて繰返し荷重を受けるコンクリートの塑性ひずみの算定方法を提案した。

    CiNii

  • Fost Resistance of Re-used Concrete a Few Cycles

    FUJIMOTO Naofumi, SATO Yasuhiko, KONNO Katsuyuki, IMAMURA Akihisa

      22 ( 2 ) 1165 - 1170  2000.06

    CiNii

  • A Study on Compressive Fatigue Behavior of Concrete in Water

    FUJIMOTO Masayuki, SATO Yasuhiko, KAKUTA Yoshio

      22 ( 3 ) 205 - 210  2000.06

    CiNii

  • A Study on the Bond Fatigue Behavior of Carbon Fiber Sheet

    MORIWAKI Wataru, SATO Yasuhiko, UEDA Tamon, KAKUTA Yoshio

      22 ( 3 ) 271 - 276  2000.06

    CiNii

  • Experimental Study on Shear Strength of RC Slabs Externally Strengthened with Carbon Fiber Sheets

    TAKAHASHI Yoshihiro, SATO Yasuhiko

      22 ( 3 ) 721 - 726  2000.06

    CiNii

  • Frost Resistance of Re-used Concrete a Few Cycles

    FUJIMOTO Naofumi, SATO Yasuhiko, KONNO Katsuyuki, IMAMURA Akihisa

    Proceedings of the Japan Concrete Institute   22 ( 2 ) 1165 - 1170  2000.06

     View Summary

    再生骨材を用いたコンクリートの耐凍害性に及ぼす水セメン比、置換率、および、粗骨材を繰り返し利用することによる影響について検討した.さらに凍結融解試験後の供試体を用いた曲げ試験および圧縮試験を行い、力学特性に及ぼす凍害の影響についても検討した、その結果、粗骨材吸水率が大きくても、水セメント比を小さくバージン骨材との併用率を大きくすることにより耐凍害性が改善されること、再生骨材、再々生および再々再生コンクリート間に大きな差異が認められないことを示した.

    CiNii

  • A Study on Compressive Fatigue Behavior of Concrete in Water

    FUJIMOTO Masayuki, SATO Yasuhiko, KAKUTA Yoshio

    Proceedings of the Japan Concrete Institute   22 ( 3 ) 205 - 210  2000.06

     View Summary

    本研究において,上限応力および環境条件(水中と気中)を変えたコンクリートの圧縮疲労試験を行い,その基本的な変形特性を明らかにすることを試みた。破壊に至るまでに蓄積されるエネルギー量は,応力比(上限応力/圧縮強度)が大きいほど,また,気中よりも水中の方が小さくなること,塑性ひずみを疲労破壊直前の全ひずみで除した場合,蓄積エネルギーの増加に対する塑性ひずみの変化は,応力比のみの関数として表すことが可能であることなどを明らかにした。

    CiNii

  • A Study on the Bond Fatigue Behavior of Carbon Fiber Sheet

    MORIWAKI Wataru, SATO Yasuhiko, UEDA Tamon, KAKUTA Yoshio

    Proceedings of the Japan Concrete Institute   22 ( 3 ) 271 - 276  2000.06

     View Summary

    コンクリートにエポキシ樹脂を用いて接着した炭素繊維シートの疲労荷重下における付着挙動に及ぼす炭素繊維シートの積層数と作用最大引張力の影響を実験的に明らかにした。また実験結果より、炭素繊維シートの付着応力-すべり関係の特徴を定性的に明らかにした。

    CiNii

  • Experimental Study on Shear Strength of RC Slabs Externally Strengthened with Carbon Fiber Sheets

    TAKAHASHI Yoshihiro, SATO Yasuhiko

    Proceedings of the Japan Concrete Institute   22 ( 3 ) 721 - 726  2000.06

     View Summary

    相対する二辺が単純支持され、他の二辺が自由のRCスラブの下面に炭素繊維シートを貼付し,スラブ上面の中央及び自由縁に向かって荷重が偏心して作用した場合のスラブの破壊性状・たわみ性状・主鉄筋のひずみ性状・シートのひずみ性状・一部供試体においてはコンクリート表面のひずみ性状を実験的に検討した。実験に用いた供試体は全部で9体である。中央載荷の場合は押抜きせん断破壊であった。下面にシートを貼付することによりその最大荷重は,シート無し供試体の約1.3倍の値を示した。また,荷重が自由縁近傍に作用した場合,シートの補強効果は殆ど期待できない。

    CiNii

  • FUNDAMENTAL STUDY ON BOND MECHANISM OF CARBON FIBER SHEET

    SATO Yasuhiko, ASANO Yasuyuki, UEDA Tamon

    Doboku Gakkai Ronbunshu   648   71 - 87  2000.05

     View Summary

    The aim of this study is to clarify the bond mechanism of Carbon Fiber Sheet (CFS) attached to concrete using epoxy resin and to propose the numerical methods which can simulate the bond behavior of CFS and its bond strength. A bond-slip-strain relation for CFS has been developed based on the bond characteristic which was clarified by means of experimental observation. A numerical method using the bon d-slip-strain relation can simulate the actual bond behavior. This paper also reports that a bond strength equation developed by the numerical analysis can predict the experimental results with good accuracy.

    DOI CiNii

  • オランダ デルフト工科大学から

    佐藤 靖彦

    コンクリート工学 = Concrete journal   37 ( 11 ) 54 - 56  1999.11

    CiNii

  • Experimental Study on Reinforcing Effect of RC Slabs Externally Strengthened with Carbon Fiber Sheets

    TAKAHASHI Yoshihiro, SATO Yasuhiko

    Proceedings of the Japan Concrete Institute   21 ( 3 ) 541 - 546  1999.06

     View Summary

    相対する二辺が単純支持され、他の二辺が自由のRCスラブの下面に炭素繊維シートを貼付し,スラブ上面の中央に静的集中荷重が作用した場合のスラブの破壊性状・たわみ性状・主鉄筋のひずみ性状・シートのひずみ性状について実験的に検討した。実験に用いた供試体は全部で6体である。その内1体は,シートを貼付しない供試体で基準供試体とした。他の5体の供試体の内訳は,下面全面にシートを貼付したもの3体,下面にシートを10cm間隔でゼブラ状に貼付したもの2体である。供試体全て押抜きせん断破壊であった。下面にシートを貼付することによりその最大荷重は,基準供試体の最大で1.58倍の値を示した。

    CiNii

  • A Study on Continuous Fiber Flexible Reinforcement as Shear Reinforcement for Concrete Members

    TOMITA Saki, KANZAKI Satoshi, SATO Yasuhiko, KOBAYASHI Akira

    Proceedings of the Japan Concrete Institute   21 ( 3 ) 1501 - 1506  1999.06

     View Summary

    本論文において、連続繊維フレキシブル筋の被覆チューブの厚さを薄くし、さらに、端部定着を施すことによりRCはりのせん断耐力が大きくなることを明らかにした。さらに、被覆チューブの厚さを実験変数としたU字型引張試験を通じて、折り曲げ部で繊維が滑り抜けていること、チューブの変形が引張荷重方向の変位を大きくし、繊維の効果を発揮させにくくしていることがせん断耐力に大きな影響を及ぼす要因であることを示した。

    CiNii

  • SHEAR RESISTING CAPACITY OF A REINFORCED CONCRETE PIER RETROFITTED WITH CARBON FIBER SHEET

    SIRBU Gabriel, YOSHIHIRO Torii, SATO Yasuhiko, UEDA Tamon

      20   233 - 238  1999.04

     View Summary

    This paper presents the study results of a reinforced concrete pier with carbon fiber sheet (CFS) retrofitting. Plain reinforced concrete specimens were used for comparison. The experimental variables are: type of loading, ratio of CFS reinforcement. Specimens were subjected to static monotonic lateral loading or static cyclic lateral loading.

    CiNii

  • 1072 Experimental Study of Flexural Behavior of Aramid FRP Rods Reinforced Concrete Beam with Externally Bonded Carbon Fiber Sheet

    TAKAHASHI Yoshihiro, HATA Chihiro, MAEDA Toshiya, SATO Yasuhiko

    Proceedings of the Japan Concrete Institute   20 ( 1 ) 509 - 514  1998.06

     View Summary

    矩形断面はりの引張主鉄筋に降伏現象のないアラミドロッドを用い,はり下面に炭素繊維シートを貼付し,二点対称集中荷重を作用させ,ロッド及びシートのひずみ性状,はりの曲げ性状,及び破壊性状について実験的に検討した。その結果,曲げ補強のため供試体下面に貼付した炭素繊維シートの積層数の違い(一層と三層)による終局耐力の差はほとんど見られなかった。しかし,曲げ補強シート貼付後さらにシートでU字巻き上げ補強することにより下面シートの剥離進行が制御され,終局耐力及び終局変位が増加した。また,下面のシートが剥離する前までのはりの変形は,断面分割法により概ね予測することができた。

    CiNii

  • Shear Resisting Capacity of a Reinforced Concrete Pier Retrofitted with Carbon Fiber Sheet

    SIRBU Gabriel, YOSHIHIRO Torii, SATO Yasuhiko, UEDA Tamon

      20 ( 1 ) 533 - 538  1998.06

     View Summary

    This paper presents the study results of a reinforced concrete pier with carbon fiber sheet (CFS) retrofitting. Plain reinforced concrete specimens were used for comparison. The experimental variables are: type of loading, ratio of CFS reinforcement. Specimens were subjected to static monotonic lateral loading or static cyclic lateral loading.

    CiNii

  • 3159 Mechanical Property of Recycled Concrete under Lateral Confinement

    KONNO Katsuyuki, SATo Yasuhiko, UEDA Tamon, ONAGA Masaaki

    Proceedings of the Japan Concrete Institute   20 ( 3 ) 949 - 954  1998.06

     View Summary

    本研究では,再生骨材コンクリートの力学的特性として拘束下における強度および変形性能を把握することを目的としている.充填するコンクリートの一軸圧縮強度の変化にともなうコンクリート充填鋼管柱の変形性状は再生骨材コンクリートを用いた場合も普通骨材コンクリートを用いた場合と同様であることを明らかにした.また,再生骨材コンクリートのヤング係数は普通骨材コンクリートに比較して小さいことを考慮すれば,再生骨材コンクリート充填鋼管柱の剛性を概ね推定できることを示したが,強度の推定にはボアソン比と相関がある弾塑性域での体積膨張を考慮することが重要であることを示した.

    CiNii

  • Effect of loading speed on fatigue characteristics in water of reinforced concrete members.

    藤本将行, 水河洋介, 佐藤靖彦, 上田多門

    土木学会年次学術講演会講演概要集 第5部   53rd  1998

    J-GLOBAL

  • Mechanical Characteristics of Concrete Member with Continuous Fiber Frexible Reinforcement.

    富田早季, 佐藤靖彦, 上田多門, 角田与史雄, 小林朗

    日本コンクリート工学協会論文集   ( 43 )  1998

    J-GLOBAL

  • SHEAR STRENGTH OF REINFORCED AND PRESTRESSED CONCRETE BEAMS WITH SHEAR REINFORCEMENT

    SATO Yasuhiko, UEDA Tamon, KAKUTA Yoshio

      ( 29 ) 233 - 247  1997.06

    CiNii

  • 2091 A Damage of Concrete under Cyclic Loading

    TADOKORO Toshiya, SATO Yasuhiko, UEDA Tamon, KAKUTA Yoshio

    Proceedings of the Japan Concrete Institute   19 ( 2 ) 567 - 572  1997.06

     View Summary

    本研究は、無筋の梁部材を用い、繰返し荷重を受けるコンクリートのひび割れ進展のメカニズムを明らかにすることを試みた。梁の曲げひび割れの下縁で、除荷時に圧縮力が作用することにより、ひび割れ先端部分に引張力が作用する。その結果、新たなひび割れが成長することを実験的に明らかにした。また、ひび割れが閉じようとする時に、ひび割れ面で圧縮力が作用することを考慮に入れた構成則を用いた有限要素解析により実験結果を反映することが可能となった。

    CiNii

  • 2237 Characteristics of Column of Recycled Concrete Encased by Steel Tube Subjected to Axial Compression

    KONNO Katsuyuki, SATO Yasuhiko, KAKUTA Yoshio, OHIRA Masaji

    Proceedings of the Japan Concrete Institute   19 ( 2 ) 1443 - 1448  1997.06

     View Summary

    本研究において,再生骨材を用いたコンクリート充填鋼管柱の軸圧縮特性を実験及び解析的に検討した.すなわち,再生骨材を用いたコンクリートは,普通骨材を用いたコンクリートに比べ,内部の損傷(破壊)速度がより大きく,このため,部材剛性及び終局耐力が若干低下するが,実用に耐えうる性能を有していることを明らかにした.

    CiNii J-GLOBAL

  • 2265 Flexural Capacity and Deformation of Reinforced Concrete Beam with Carbon Fiber Sheet

    TAKAHASHI Yoshihiro, SATO Yasuhiko, MAEDA Toshiya, UEDA Tamon

    Proceedings of the Japan Concrete Institute   19 ( 2 ) 1611 - 1616  1997.06

     View Summary

    本研究において、鉄筋コンクリートはりの下面に炭素繊維シートを貼り付けた場合と、剥離破壊を抑制することを目的として、下面に貼り付けた炭素繊維シートにさらにその上から炭素繊維シートをU字に巻き付けた場合におけるRCはりの破壊性状、変形及び耐力の差異を明らかにした。

    CiNii

  • Shear capacity of reinforced concrete column reinforced by carbon fiber sheet.

    佐藤靖彦, 上田多門, シルブ ガブリエル

    自然災害における地盤の防災および構造物の復旧と補強シンポジウム論文集    1997

    J-GLOBAL

  • SHEAR STRENGTH OF REINFORCED AND PRESTRESSED CONCRETE BEAMS WITH SHEAR REINFORCEMENT

    SATO Yasuhiko, UEDA Tamon, KAKUTA Yoshio

    土木学会論文集 = Proceedings of JSCE   544   43 - 52  1996.08

    DOI CiNii

  • 2244 Shear Behavior of RC Beams Reinforced with Carbon Fiber Sheet

    SATO Yasuhiko, TANAKA Takayuki, UEDA Tamon, ONO Sadamu

    Proceedings of the Japan Concrete Institute   18 ( 2 ) 1469 - 1474  1996.06

     View Summary

    本研究において、炭素繊維シートで補強した鉄筋コンクリートはりのせん断性状を実験的検討により明らかにした。すなわち、炭素繊維シートを側面に補強した鉄筋コンクリートはりのせん断力は、コンクリートが受け持つせん断力と斜めひび割れ域での炭素繊維シート及びスターラップにより受け持たれるせん断力の和として表されることを明らかにするとともに、炭素繊維シート及びスターラップが受け持つせん断力の算定方法の考え方を提示した。

    CiNii

  • SHEAR STRENGTH OF PRESTRESSED CONCRETE BEAMS WITH FRP TENDON

    SATO Yasuhiko, UEDA Tamon, KAKUTA Yoshio

    COMPOSITE CONSTRUCTION III   ( 27 ) 189 - 208  1996.06

    CiNii

  • Analytical Prediction of Cover Cracking Due to Corrosion of Reinforcement.

    亀谷英樹, 佐藤靖彦, 上田多門, 角田与史雄

    コンクリート工学年次論文報告集   18 ( 1 ) 783 - 788  1996

     View Summary

    本研究では、主鉄筋が複数一列に配置されたはり部材における鉄筋腐食によるかぶりコンクリートのひび割れの性状とその発生までに要する鉄筋膨張率について有限要素法を用いた解析的な検討を行った。その結果、かぷり厚さ及びあき長さの差異による腐食ひび割れの発生方向と限界膨張率との関係を明らかにした。

    CiNii J-GLOBAL

  • QUANTITATIVE EVALUATION OF SHEAR STRENGTH OF CONCRETE BEAMS REINFORCED WITH FRP RODS

    SATO Yasuhiko, UEDA Tamon, KAKUTA Yoshio

    土木学会論文集   520 ( 520 ) 157 - 169  1995.08

    DOI CiNii J-GLOBAL

  • SHEAR STRENGTH OF PRESTRESSED CONCRETE BEAMS WITH FRP TENDON

    SATO Yasuhiko, UEDA Tamon, KAKUTA Yoshio

    土木学会論文集   520 ( 520 ) 213 - 224  1995.08

    DOI CiNii J-GLOBAL

  • FINITE ELEMENT ANALYSIS ON SHEAR RESISTING MECHANISM OF CONCRETE BEAMS WITH SHEAR REINFORCEMENT

    UEDA Tamon, PANTARATORN Nares, SATO Yasuhiko

    Journal of Materials, Concrete Structures and Pavements   520   273 - 286  1995.08

    DOI CiNii

  • 2140 Shear Strength of Deep Beams with Horizontal Bars and Stirrups

    SATO Yasuhiko, UEDA Tamon, KAKUTA Yoshio

    Proceedings of the Japan Concrete Institute   17 ( 2 ) 839 - 844  1995.06

     View Summary

    本研究において、有限要素解析に基づき、せん断補強筋を持たないディープビームに対するせん断耐力式を、水平補強筋及びスターラップを有するディープビームに対して適用できるよう修正した。本研究で提示したせん断耐力式により、実験結果を概ね評価できることを確認した。

    CiNii

  • Shear Resisting Model of Reinforced and Prestressed Concrete Beams Based on Finite Element Analysis

    Sato Yasuhiko, Ueda Tamon, Kakuta Yoshio

    Bulletin of the Faculty of Engineering,Hokkaido University   ( 171 ) p1 - 17  1994.10

    CiNii

  • 有限要素解析による連続繊維補強コンクリ-トはりのせん断耐荷性状の定性的評価

    佐藤 靖彦, 上田 多門, 角田 与史雄

    土木学会論文集   ( 484 ) p51 - 60  1994.02

    DOI CiNii

  • Analytical Evaluation on Shear Resisting Behavior of Prestressed Concrete Beams Reinforced with FRP Rods.

    佐藤靖彦, 上田多門, 角田与史雄

    コンクリート工学年次論文報告集   16 ( 2 ) 1087 - 1092  1994

    CiNii J-GLOBAL

  • 2048 Sectional Force of Statically Indeterminate Prestressed Concrete Beams Using FRP Rods as Prestressing Tendons

    TAKAHASHI Yoshihiro, KAKUTA Yoshio, SATO Yasuhiko

    Proceedings of the Japan Concrete Institute   15 ( 2 ) 289 - 292  1993.06

    CiNii

  • 2149 Analytical Evaluation on Shear Resisting Behavior of Concrete Beams Reinforced with FRP Rods as Web Reinforcement

    SATO Yasuhiko, UEDA Tamon, KAKUTA Yoshio

    Proceedings of the Japan Concrete Institute   15 ( 2 ) 881 - 886  1993.06

    CiNii

  • 2118 Experimental Study on Shear Failure of Concrete Slabs Reinforced with Grid-Shaped FRP Bars

    TAKAHASHI Yoshihiro, KAKUTA Yoshio, SATO YaSuhiko

    Proceedings of the Japan Concrete Institute   14 ( 2 ) 685 - 688  1992.05

    CiNii

  • 2109 Effect of the Stiffness of Reinforcement on Punching Shear Strength of FRP Reinforced Concrete Slabs

    SATO Yasuhiko, TAKAHASHI Yoshihiro, UEDA Tamon, KAKUTA YoShio

    Proceedings of the Japan Concrete Institute   14 ( 2 ) 631 - 636  1992.05

    CiNii

  • 2145 Punching Failure of Concrete Slabs Reinforced with FRP Rods

    SATO Yasuhiko, FURUUCHI Hitoshi, KAKUTA Yoshio, TAKAHASHI Yoshihiro

    Proceedings of the Japan Concrete Institute   13 ( 2 ) 855 - 860  1991.06

    CiNii

▼display all

Industrial Property Rights

  • コンクリート構造物の補強方法

    特許第4194894号

    小林 朗, 佐藤 靖彦

    Patent

    J-GLOBAL

Awards

  • 構造工学論文集Vol.66A論文賞

    2020.06   土木学会  

  • 吉田賞

    2020.06   土木学会  

  • セメント協会論文賞

    2013.05   セメント協会  

  • Best Basic Research Paper

    2005.06   アメリカ土木学会 Journal of composites for construction  

  • 吉田賞

    2003.06   土木学会  

  • コンクリート工学協会賞(論文賞)

    1995.05   日本コンクリート工学協会  

▼display all

Research Projects

  • 道路橋RCおよびPC床版の荷重推定と寿命予測法の開発

    日本学術振興会  科学研究費助成事業 基盤研究(B)

    Project Year :

    2020.04
    -
    2023.03
     

    佐藤 靖彦, 高橋 良輔

  • Disaster management of structures and infrastructures affected by the anticipated Nankai Trough earthquake for resilience enhancement

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)

    Project Year :

    2019.04
    -
    2023.03
     

  • Deterioration of interfacial bond property under combined effects and prediction of performance of members after intervenion

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)

    Project Year :

    2014.04
    -
    2017.03
     

    UEDA Tamon, ZHANG Dawei, KOMORI Atsuya, TAKAHASHI Jun, FUJIMA Seiji

     View Summary

    This study discloses that interfacial bond strength of FRP external bonding as strengthening of concrete structures slightly reduces or slightly increases after 18-months immersion of water, and that bond strengths of overlaying reduces with increase in temperature up to 60 degree but recovers partially after lowering temperature. Prediction formula for bond properties were proposed based on the test results. As technologies for enhancement of structural performance after strengthening, analytical methods of FRP external bonding with inserted polyurea resin layer, prediction model of strengthening effect by anchor bar for overlaying and prediction model for enhanced fatigue strength by resin injection into cracks were presented.
    For frost attack effects, prediction models for concrete damage under combined effect with fatigue and for accelerated frost damage under combined effect with salt attack were presented together with measuring method of frost damage distribution.

  • Performance recovery and life extension of deteriorated reinforced concrete members by repeated applications of repair

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research

    Project Year :

    2014.04
    -
    2017.03
     

    YOKOTA Hiroshi, SATO Yasuhiko

     View Summary

    This research focused on the performance recovery and life extension of deteriorated concrete members with repeated applications of electrochemical chloride extraction or section repair using fiber reinforced polymer cement mortar. These repair techniques are applicable for performance recovery, but may simultaneously provide detrimental effects on the micro structure of cement hydrate products. It was found from this experimental study that the repeated applications are beneficial for performance recovery and the detrimental effects are not so severely significant as those provided by the single application. Accordingly, it was concluded that the multiple applications of repair may have some limitations to realize the life extension because they accumulate local damages in cement hydration products.

  • Determinaion of damage index on long un-reinforced concrete structures relating to disaster prevention

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

    Project Year :

    2012.04
    -
    2015.03
     

    YOKOTA Hiroshi, WATANABE Yasunori, SATO Yasuhiko, KATO Ema, HASHIMOTO Katsufumi

     View Summary

    This research focused on how the comprehensive damage grading system is established for a long un-reinforced concrete structure along coastlines from the viewpoints of structural performance and functions of disaster prevention. Major damage induced in this type of structure is concrete cracking due to shrinkage of concrete and differential settlement of the structural body; accordingly, crack width, depth and position are categorized and modeled into the structural analysis tool. Moreover, shear transfer behavior between the crack surfaces was experimentally made clear. Finally, structural analysis taking into account the above behavior was carried out to quantify remaining structural performance of damaged structures. In conclusion, new criteria for damage evaluation have been proposed to access the function and performance of cracked un-reinforced concrete structures. These results may contribute to realize more effective and objective maintenance work.

  • Mechanical characteristics modeling of concrete under environmental action based on meso-scale perspective

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)

    Project Year :

    2012.04
    -
    2015.03
     

    SATO yasuhiko, SUGIYAMA Takafumi, HASHIMOTO Katsufumi

     View Summary

    Concrete structures in hot spring area, underground structures, sewerage structures are suffered from mechanical actions such as earthquake and at the same time environmental actions. However, understandings on the mechanical characteristics of concrete under combined actions are not progressing. In this study, therefore, a mass transfer model; chemical reaction analysis method for prediction of cement hydrates and porosity change under environmental actions (Ca leaching and acid attach) and a fracture analysis method considering reduction in strength, Young's modulus and facture energy based on meso scale perspective are developed and those methods are integrated so as to predict the mechanical characteristics of semi-macro concrete.

  • Development of General Method for Strengthening Design with Consideration of Life Cycle

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)

    Project Year :

    2010
    -
    2012
     

    UEDA Tamon, FURUUCHI Hitoshi, SATO Yasuhiko, ZHANG Dawei

     View Summary

    In order to develop the unified design method for strengthening by external bonding and overlaying, the followings are presented: Prediction models for various debonding types at interface between substrate concrete and reinforcing materials, Influences of fatigue, moisture, freeze thaw cycles and interface roughness on interface bond strengths, Optimum reinforcing material properties and reinforcing methods (dimension and location), Experimental evidence of enhancement of ultimate member strength by overlaying under traffic loads, and (5) Applicability of 3D numerical analysis to simulate member strength after strengthening. After compiling all the results, latest guidelines for strengthening of concrete structures as well as strength prediction models after strengthening are presented.

  • Durability Design and Conservation for Concrete Structures in Cold Region Subjected to Combined Deterioration Effects

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)

    Project Year :

    2007
    -
    2009
     

    UEDA Tamon, GOTO Yasuaki, HASEGAWA Takuya, HAMA Yukio, TAGUCHI Fumio, ENDOH Hirotake, HAYASHIDA Hiroshi, SATO Yasuhiko, WANG Licheng

     View Summary

    In concrete structures in cold regions frost damage is occurred by freeze-thaw cycles of water in the concrete. This study presents the method to measure the degree of frost damage in actual structures using ultrasonic wave. The relationship between the frost damage degree and degraded material properties is observed. The deterioration mechanism under the combined effects of frost damage and wet-dry cycles/salt attack is clarified, and then the models to simulate the deterioration is proposed. The model for numerical analysis of structures with frost damage after being repaired by overlaying is also proposed.

  • Long-term Durability Evaluation of Concrete and Construction of Exposure Environment

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)

    Project Year :

    2006
    -
    2007
     

    HISADA Makoto, SATO Yasuh, SAEKI Tatsuhiko, KISHI Toshiharu, HATTORI Atsushi, TAKEWAKA Koji

     View Summary

    The purpose of this study is to evaluate the durability of concrete through the nation-wide testing and local climate monitoring. The test has been started since 2003, and still continuing.
    From these investigations, following conclusion was clarified.
    A. For the first year
    (1) The climate condition at Tsukuba was much severe than that at Kurihama in both summer and winter. In other word, Tsukuba was colder than Kurihama in winter season, and Tsukuba was hotter than Kurihama in summer season.
    (2) Therefore, the compressive strength of concrete exposed in Tsukuba were remarkably influenced more than that in Kurihama.
    B. For the fifth year
    (1) From the results of climate condition at 17 places, several classifications could be done as the influent condition for the durability of concrete.
    (2) The curing condition at early stage of concrete production is quite important for the long term durability of concrete.

  • A Study on LCC reduction technique for traffic infrastructure under the condition of antifreezing admixture usage

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)

    Project Year :

    2004
    -
    2006
     

    UEDA Tamon, KANIE Shunji, NAWA Toyoharu, UCHIDA Kenetsu, HASIMOTO Yuichi, SATO Yasuhiko

     View Summary

    The following conclusions can be drawn.
    (1)A model for evaluating life cycle cost of pavements considering winter road traffic situation was proposed. An algorithm for the model which was developed by applying the sensitivity analysis of the probit stochastic user equilibrium (PSUE) was also proposed. Drivers' route choice behavior induced by deterioration of surface condition of pavements, change in traffic capacities brought by repair works in summer, and change in traffic capacities brought by antifreezing admixture dispersion in winter was endogenously expressed in the model. As a result, a plan for repair works and dispersion of antifreezing admixture which minimizes the life cycle cost by taking above mentioned driviers' behavior into account was obtained by carrying out a numerical experiment.
    (2)The integrated database combining the data of varieties, such as the road surface condition, the drive condition, the weather information and so on was created. As a case study using this database, the research solved the relation between the road surface condition and the drive condition in winter, and showed that the useful information to the traffic administrator and the road user could be created. This result showed the validity of the anti-freezing agent in the case of many, and clarified further the conditions on which that effect fades.
    (3)A calculation example of 2 dimensional Moving Element Method (MEM) with a vehicle model was introduced and it is verified that an interactive behavior between a vehicle and plate can be successfully analyzed by this method. The developed MEM has following advantages against conventional time-domain FEM for continuous structure under the loading due to a moving vehicle, (a) MEM can fix the loading position in the model regardless of time elapsingwhereas FEM needs large model corresponding to the moving range of the vehicle, (b) Since limited area or length near the loading point is finitely modeled for MEM, the degrees of freedom required for the analysis become smaller than those for a conventional FEM.
    (4)Damage evaluation method for infrastructure based on fractal analysis was developed.
    (5)A bond model for FRP sheet which can consider the influence of Young's modulus of resign and sheet was developed.
    (6)Surface protective agent which can penetrate into 40 mm depth from concrete surface was developed.

  • 疲労と凍結融解を同時に受ける鉄筋コンリートはり部材の非線形解析による寿命予測

    日本学術振興会  科学研究費助成事業 若手研究(B)

    Project Year :

    2003
    -
    2005
     

    佐藤 靖彦

     View Summary

    本研究は,疲労と凍結融解を同時に受ける鉄筋コンクリートはり部材の寿命予測手法を構築することを目的として行った.すなわち,凍結融解による劣化と疲労荷重による損傷を考慮できるFEMプログラムを開発し,かつ,部材レベルでの促進試験を行い,実験結果と解析結果とを比較することにより本解析手法の妥当性を示すとともに,劣化メカニズムを解明する.3年間の研究成果を以下に列挙する.
    ・鉄筋コンクリートはり部材の凍結融解試験を実施した.その結果,凍結融解により劣化することにより,はりの破壊形式が曲げ降伏破壊からせん断圧縮破壊へ移行し,さらに大きな劣化度を有する場合には,せん断圧縮破壊から曲げ圧縮破壊へと移行することを明らかにした.
    ・鉄筋の定着強度が,凍結融解作用により大きく低下することを実験的に明らかにした上で,凍害による損傷を考慮できる付着構成則の開発を行った.
    ・静的荷重を作用させることでコンクリートに予め損傷(マイクロクラック)を与えた場合,凍結融解抵抗性が著しく低下することを明らかにした.さらに,初期損傷を有するコンクリートが凍結融解作用を受ける場合のコンクリートの応力ひずみ構成則を開発した.
    ・既往の実験結果に加え,温度や湿度を制御した疲労及びクリープ試験を通じて,コンクリートの変形性状を明らかにするとともに,静的荷重を対象として開発された弾塑性破壊モデル(前川モデル)を基本とした変形モデル,すなわち,持続荷重や疲労荷重を受けるコンクリートの破壊までの応力-ひずみ関係の定量化を行った.さらに,この変形モデルを2次元非線形有限要素解析プログラムに組み込んだ.
    ・本研究で開発した構成則を導入した有限要素解析を実施し,凍害による劣化が,鉄筋コンクリートはり部材の変形と耐力に及ぼす影響を明らかにした.

  • 微生物を利用した再生骨材の製造とその品質に関する研究

    日本学術振興会  科学研究費助成事業 萌芽研究

    Project Year :

    2003
    -
    2004
     

    佐藤 太裕, 角田 與史雄, 佐藤 靖彦, 伊藤 正澄, 松村 宇, 佐藤 太裕

     View Summary

    本研究は,バクテリアリーチングにおいて利用されてきた方法を基本とし,微生物を利用して再生骨材を製造し,その品質を明らかにすることで,再生骨材の製造に微生物を利用することの有用性を示そうとするものである.
    本研究において,多種多様な微生物の中から硫黄酸化細菌と鉄酸化細菌に着目した基礎実験を行った.すなわち,細菌の有無,骨材の有無,コンクリート塊の大きさ,炭酸化の有無がペースト及びモルタルの劣化度に及ぼす影響を実験的に明らかにした.得られた知見を以下に列挙する.
    ・硫黄酸化細菌及び鉄酸化細菌が増加すると培地のPHを低下させ,モルタルをよく剥離させ,カルシウムイオンを溶脱させる.
    ・硫黄酸化細菌と鉄酸化細菌の活動は,コンクリート塊のサイズが5-20mmの範囲の方が,5mm以下の範囲よりも活発化した.これは塊のサイズが小さいと培地に溶け出すアルカリ量が多くなるためである.それゆえ,微生物を摂取する前に炭酸化させた方が良い.
    ・硫黄酸化細菌と鉄酸化細菌が骨材に及ぼす影響は工学的に無視できる.
    ・酸性硫黄温泉水を培地として利用した場合,効率よくカルシウムイオンを遊離させることができる.しかし,コンクリート塊の表面に生成される腐食性生物が硫酸イオンの浸透を阻止する為,反応速度が著しく低下する.

  • Development of Highway Maintenance System using Deterministic Model for Structure Degradation in Cold Region

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)

    Project Year :

    2002
    -
    2004
     

    KAGAYA Seiichi, OBATA Takashi, NAWA Toyoharu, SATO Yasuhiko, HASHIMOTO Yuichi, HAGIWARA Toru

     View Summary

    The influences from dispersion of antifireezing admixture, toward function of road transport and toward deterioration of road facilities, are analyzed in this study. This study aimes for the enhancement of systems of operation and maintenance for dealing with the influences. Firstly, an examination on the technologies of operation and maintenance for road network which support transport system is made. Then, a Web-based database system which can capture the real road traffic situation in winter, both temperaly and spatialy, is developed. Finally, an examination on the optimal amount of antifreezing admixture dispersion problem considering the changes in modal shares made by passengers is also carried out. An efficient usage of antifreezing admixture will be brought out by both technologies regarding the effective road maintenance, and regarding the control of passengers' travel behaviors determined by characteristics of transport network.
    A detailed mechanism of deterioration in concrete structure caused by antifreezing admixture is captured. An examination on the strengthening resistibility to penetration of sodium into cement, which is known as main material of concrete, is carried out, new tangible method for that is then developed. An examination on priority decision making system for maintenance and repair works is carried out by taking steel structure as an example. Furthermore, a development of diversification risk system targeted to destruction of structure, by taking disaster as am example, is made an attemp. Those works will make it possible to develop both structures which are hard to be deteriorated by sodium, and well-designed structure management system.
    Some important achievements, which could contribute to a development of road management system, have been made in this study by assuming usage of antifreezing admixture. However, a development of comprehensive management system comprised of technologies mentioned above are intended for in the first stage, only indication on the direction toward the comprehensive system is made against our objectives. Some examinations on what kinds of effects are botained by organizing the technologies dealt with in the present study will be made in the fixture.

  • Research on Simply Connection of Members for Mixed Structure

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

    Project Year :

    2002
    -
    2003
     

    KAKUTA Yoshio, FURUUCHI Hitoshi, UEDA Tamon, HAYASHIKAWA Toshio, SATO Yasuhiko

     View Summary

    The followings are summary of what have been obtained in the experimental research of the loop joint.
    From static tension tests with loop joint, two types failure mode of yielding of longitudinal bar and crushing of core concrete in the loop joint are observed. In case of crushing the core concrete, ultimate strength is large as the loop height, the splice length and the bar diameter are increased Mechanical model for estimating the compressive stress of the core concrete is conducted. The capacity of the compressive stress can he estimated to define the limit stress determined form the concrete strength and the bar diameter From the fatigue tests using beam specimens, it is shown that the fatigue life may be decrease due to occur the local bending at the joint.
    The followings are summary of what have been obtained in the experimental research of the bearing-type connection.
    It is clarify that a cracking load is computed by using EC beam theory with the bond strength of the hearing-type connection and a compression zone at the connection resists to the shear force after cracking when the connection are subjected to bending moment. The equation for the shear transfer strength is conducted in such this case.

  • Unified Bond Model for Externally Bonded Reinforcement

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

    Project Year :

    2001
    -
    2003
     

    UEDA Tamon, KONNO Katsuyuki, SATO Yasuhiko, FURUUCHI Hitoshi

     View Summary

    This study presents a unified local bond stress-slip model for interface between concrete and externally bonded reinforcing material (shear bond model). The shear bond model was derived based on a reinforcing material stress-slip relationship at loaded end of pullout bond test, so that necessary measurement was simplified and the data scatter problem was minimized. The shear bond model needs only two material constants, interfacial fracture energy and interfacial ductility factor. The shear bond model was expanded to be bond stress-slip-reinforcing material strain model to express cases with a short bond length. Both original and expanded shear bond models consider effects of mechanical properties of reinforcing materials, adhesive materials and concrete substrate. Besides the shear band model, the prediction formula for interfacial fracture energy, effective bond length and bond strength for given anchorage length are presented. Reliability of the proposed unified shear bond model together with the proposed formula for interfacial fracture energy, effective bond length and bond strength for a given bond length is presented by comparing the calculated results with experimental results.
    Tension bond model is examined experimentally and it is disclosed that the bond strength (or interfacial fracture energy) is not affected by stiffness of adhesive materials, which is different from the cases of shear bond model. A test method to represent a mixed mode for bond (shear and tension bond) is newly developed. Using this method, an interaction diagram of shear bond strength and tension bond strength is presented, which shows that the shear bond strength is reduced only by 10% even under tension bond stress equal to 90% of the tension bond strength. The theoretical method to calculate punching out capacity of reinforcing material externally bonded in orthogonal direction is also presented.

  • 性能評価に基づくコンクリート構造物のライフサイクルマネージメントに関する研究企画

    日本学術振興会  科学研究費助成事業 基盤研究(C)

    Project Year :

    2002
     
     
     

    杉山 隆文, 下村 匠, 中村 光, 山田 義智, 佐藤 靖彦

     View Summary

    本研究の目的は,コンクリート構造物の性能をライフサイクルを通じて適切にかつ合理的に維持するための管理技術の構築について,共同で行う研究計画に対して企画調査を行うことであった.そこで本研究では,コンクリート構造物の劣化・損傷,性能低下,対策,対策後の性能回復・向上,再劣化,性能の再低下における時間的なサイクルの過程を定量的にシミュレートするモデルの開発に対して,材料の専門家と構造の専門家が共同して,現状の技術レベルおよび課題の抽出,モデル開発の有効性を中心に企画調査を実施することとした.
    本企画調査によって,補修材料のうち例えば,コンクリートの表面保護材料の耐久性が不明であり,補修後の維持管理やライフサイクルを通じたメンテナンスを考えた場合,早急にこれらの材料の耐久性の定量化が重要であることを明らかにした.これに対して,特に本研究では,シート接着鉄筋コンクリート供試体の電食試験結果と,シートの塩化物イオン拡散係数を仮定した数値解析結果とを比較することにより,シートおよび樹脂層の拡散係数を導出し,時間軸における評価手法の開発の妥当性を検討した.さらに,断面修復材のうち高耐久性のある材料についても電気泳動法によって塩化物イオン拡散係数を算出し,耐久性の合理的な評価の可能性を検討した.一方,特に厳しい海洋環境下や凍結融解作用下で劣化したコンクリート構造物の補修,補強や再劣化の実態調査では,補修後に再補修が必要となるケースが見られ,室内実験での材料評価に加えて,施工の要因を採り入れた総合的な対策が重要であることも明らかになった.
    以上より本研究は,コンクリート構造物のライフサイクルマネージメントの合理化,高度化に必要となる具体的な研究計画を立案できる可能性や必要とされる要素技術を明らかにした.

  • Unified Approach for Evaluation of Shear Strength and Ultimate Deformation of Concrete Members Reinforced with Various Materials

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

    Project Year :

    2000
    -
    2002
     

    UEDA Tamon, KONNO Katsuyuki, SATO Yasuhiko, FURUUCHI Hitoshi

     View Summary

    The summary of conclusions obtained by experimental and numerical analyses in this study is as follows :
    ・The equation to predict the fracturing strength of Carbon Continuous Fiber Flexible Reinforcement (C-CFFR) at bent portion and the model to predict the transferred tensile force by C-CFFR at bent portion were proposed. Three dimensional finite element analyses, in which the proposed strength equation and the force transfer model for C-CFFR were introduced, could predict the mechanical properties of C-CFFR observed in the experiment.
    ・It was observed that the ultimate deformation of concrete columns with Polyacetal Continuous Fiber Flexible Reinforcement (P-CFFR) as tie reinforcement was greater than that of columns with steel tie reinforcement whose volume ratio is the same. This is because P-CFFR did not fracture even at ultimate deformation and because P-CFFR can be arranged inside the core concrete. The prediction formulae for P-CFFR strains were proposed based on the experimental results.
    ・The unified model for bond stress-slip relationship at the interface between continuous fiber sheet and concrete was proposed for finite element analysis of concrete members reinforced with continuous fiber sheet. Based on the finite element analysis of reinforced concrete prism with continuous fiber sheet subjected to uniaxial tension, it was found that the concrete tension stiffness is greater than the case without continuous fiber sheet.
    ・In order to obtain the precise prediction of the shear tension strength of reinforced concrete members, which is necessary for finite element analysis to predict shear and ultimate deformation of concrete members reinforced with various materials, it is necessary to model precisely the force transfer along the major shear crack.

  • Development of Analytical System for Damage and Deterioration of Concrete Structures

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

    Project Year :

    1999
    -
    2001
     

    SHIMOMURA Takumi, SATO Yasuhiko, SUGIYAMA Takafumi, NAKAMURA Hikaru, TOKUSHIGE Hidenobu, KONNO Katsuyuki

     View Summary

    The objective of this research project is to develop an analytical system that can predict performance of concrete structures subjected to various load and environmental actions. Following results were obtained.
    1) A computer program for numerical simulation of time-dependent performance change of RC bridges subjected to chloride attack was developed. It can predict effectiveness of some rehabilitation techniques as desalination method and retrofitting of CF sheet on service life of structures.
    2) Material models in the computational system mentioned above were improved, which are material transport models in cracked concrete, corrosion model of reinforcing bar in concrete and tension stiffening model for corroded RC members.
    3) 3D nonlinear FEM program that can simulate post peak behavior of various types of RC structures was developed.
    4) A testing apparatus to examine gas permeability in cracked concrete was developed. Using this apparatus, resistance of damaged concrete against ingress of aggressive agent was investigated.
    5) Constitutive models for concrete were improved to ensure a damage analysis of concrete structures under various conditions. A constitutive model for plane concrete under cyclic tensile and compressive stress was formulated. A constitutive model for plane concrete damaged by freeze-thaw action was formulated. A constitutive model for bonding behavior of CF sheet and concrete under static and cyclic load was formulated.

  • Study on FE analysis of damage process due to fatigue loading and shear fatigue strength of RC members in water

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B).

    Project Year :

    1999
    -
    2000
     

    KAKUTA Yoshio, SATO Yasuhiko, FURUUCHI Hitoshi, UEDA Tamon

     View Summary

    The followings are summary of what have been obtained in this research.
    /FE analysis considering strength and stiffness reductions caused by damage due to fatigue loading can predict fatigue life of RC beams without stirrups. However the analysis cannot evaluate its deformation precisely because time-dependent deformation is not considered.
    /Longitudinal strain and volumetric strain curve observed under compressive stress does not differ from different loading conditions.
    /Longitudinal strain and Young's modulus curve observed under compressive stress does not differ from different loading conditions.
    /Plastic strain in fatigue test increases as applied maximum force becomes greater.
    /A constitutive model which can consider influence of loading speed was developed. The plastic strain in the model consists of plastic strain caused by cracks and creep strain. The model can be applicable to the both cases of static and fatigue loading.
    /It was clarified through the numerical analysis using the proposed model that creep strain greatly affects fatigue life, fatigue strength predicted by the model is slightly greater than that calculated by an empirical equation and ultimate strain decreases linearly as stress at failure becomes smaller.
    /In static test after fatigue test in water, shear force carried by stirrups in a RC beam increases as applied shear force increases but shear force carried by concrete does not because redistribution caused by compression failure in concrete compression zone takes place.
    /To develop fatigue design method of RC members in water, not only fatigue strength of plain concrete but also shear resisting forces in truss mechanism in RC member must be quantified.

  • Study on Fretting Fatigue of Prestressing Cable at, Deviator

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

    Project Year :

    1998
    -
    1999
     

    KAKUTA Yoshio, SATO Yasuhiko, FURUUCHI Hitoshi, UEDA Tamon

     View Summary

    The followings are summary of what have been obtained in this research.
    ・ Fatigue strength of prestressing strand under effect of fretting is apparently smaller than that under ordinary fatigue loading.
    ・ Fretting fatigue strength is influenced by stress range, slip range and contacting force. The greater stress range is, and the greater contacting force is, the smaller becomes the fatigue strength. The experimental fact indicates that how slip range influences fretting fatigue strength may depend on magnitude of slip range. Extent of influence of stress range and slip range is greater than that of contacting force.
    ・ It is necessary to consider effect of slip range in the direction normal to strand axis besides that in the direction of the strand axis.
    ・ Fretting fatigue occurs at contacting point between strands rather than between wires in the same strand. This fact indicates that there is the effect of slip range.
    ・ Although contacting force is considered greater at inner contacting points than at outer one at deviator, location of fretting fatigue fracture was found almost evenly. This fact indicates either that with magnitude of contacting force observed in the experiment fretting fatigue strength is hardly affected by change in contacting force, or that actual contacting force in the experiment did not change by the location.
    ・ Grouting in protection tube for cable and resin coating of strand can increase fretting fatigue strength, However, it is difficult to prevent fretting fatigue fracture by providing them only.
    ・ Restriction of grout movement by taper inside protection tube or spacer of strand for reduction of contacting can prevent fretting fatigue fracture.

  • 静的及び繰返し荷重下における連続繊維シートの付着・定着機構

    日本学術振興会  科学研究費助成事業 奨励研究(A)

    Project Year :

    1998
    -
    1999
     

    佐藤 靖彦

     View Summary

    本研究の主たる実績を以下に示す。
    1.本研究において,静的荷重下における連続繊維シートの付着機構を実験的に明らかにし,得られた付着機構に基づき付着応力-すべり-ひずみ関係(以下「付着モデル」)を構築した。本付着モデルは,コンクリート強度,積層数,接着幅の影響を考慮できるものであり,実際の剥離発生・進展過程,さらには,剥離耐力を精度良く予測できるものである。
    2.疲労荷重を受ける連続繊維シートの付着機構および疲労寿命を実験的に明らかにし,静的荷重に対して開発された付着モデルの疲労荷重を受ける場合への拡張を図った。一定の荷重比(上限荷重/静的付着耐力)で比べた場合,連続繊維シートの剛性が大きい方ほど,局部的な付着応力が静的荷重時の局部付着強度に比べ小さくなることにより,疲労寿命が長くなることを明らかにした。また,付着モデルを用いた数値計算より,局部付着応力比(局部付着応力の上限値/静的局部付着強度)と疲労寿命との関係は,剛性によらずほぼ一義的な関係で記述できることを示した。
    3.本付着モデル及び鉄筋に対する既往の付着モデルを用いた,連続繊維シートで補強した鉄筋コンクリートの一軸引張挙動の数値シミュレーション手法を構築した。本手法は,連続繊維シートの剛性が大きいほどひび割れ間隔が小さくなることや鉄筋の付着応力が小さくなることなどの実験的事実を定量的に評価することができる。また,本手法を用い,連続繊維シート補強鉄筋コンクリートの平均応力-平均ひずみ関係をも構築した。本関係において,コンクリートの平均応力-平均ひずみ関係は,コンクリートの引張強度とともに鉄筋比およびシートの補強筋比により表される。

  • AN INVESTIGATION ON THE DYNAMIC BEHAVIOR OF SUBMERGED FLOATING TUNNELS

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

    Project Year :

    1997
    -
    1999
     

    MIKAMI Takashi, KANIE Shunji, YOSHIMURA Jin, SATO Yasuhiko

     View Summary

    The purpose of this study is to investigate the characteristics of the dynamic behavior of submerged floating tunnels under wave and seismic action, which are critical forces in design. Moreover, effective beam model for discussion on the design of structure is also presented.
    The most important findings under wave force are summarized as follows;
    For leg arrangement Type-A :
    1. Although lateral displacement is great, slack is least likely to occur with this arrangement.
    2. The rigidity of the joints between tunnel elements has a major effect on the lateral displacement of the tunnel as a whole. The ideal type of joint for Type-A would be a pin joint. Lateral displacement and the maximum bending moment in rigid joints increases with the angle of wave incidence.
    For leg arrangement Type-C :
    1. Lateral displacement is much less than in type A, but slack is more likely to occur.
    2. No significant variations in lateral displacement are found with different joint rigidities.
    The results of analysis under seismic wave can be summarized as follows:
    1. If the natural period of the structures is long enough comparing to the predominant period of seismic wave, maximum response of displacement or bending moment for design are approximately predictable by an analysis with simultaneous excitation. When the natural period of the structure is close to the predominant period of seismic wave, propagation velocity plays an important role for dynamic response and it should be taken into account.
    2. For prediction of sectional force like the bending moment at the joints, propagation velocity should be carefully decided.
    In order to discuss the global behavior of the structure, a beam model on elastic foundation is developed for submerged floating tunnel with tension legs spaced at equal interval. It Is shown that the approximation of a uniform continuous elastic foundation is reasonable whenever kィイD2vィエD2hィイD13ィエD1/(6EI)≦0.2.

  • A DESIGN METHOD OF ROAD TUNNELS IN COLD REGION

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)

    Project Year :

    1997
    -
    1998
     

    MIKAMI Takashi, SATO Masashi, YOSHIMURA Jin, SATO Yasuhiko

     View Summary

    Icicles and side wall ices in tunnels became a problem for transportation and maintenance. Recently a heat insulator for icicle prevention at the lining surface has been developed in the existing tunnels. The purpose of this study is to propose a simplified design procedure for heat insulator.
    This project is summarized as follows :
    (l) A simple practical equation for estimating the thickness of heat insulator is presented. The equation is obtained by using a one-dimensional tunnel-ground model and a non-steady periodic thermal analysis. A comparison with other solutions suggests that the proposed equation provide satisfactory accuracy. By using the equation presented, we can reasonably determine the optimum material of heat insulator and its optimum thickness. In addition, the equation is useful for a better understanding for the thermal characteristics of the tunnel-ground system.
    (2)In order to identify unknown thermal parameters (thermal conductivity and heat capacity in ground) in appearing the proposed equation, the extended Kalman filter in combination with the one-dimensional finite element thermal analysis is used. A comparison of the temperatures calculated from identified parameters with the measured fild data shows that the method is sufficiently accurate for practical purposes.
    (3)In order to estimate the unknown temperatures at a planning site of road tunnels, Semi-Yariogram is used on the basis of the a stochastic method. A comparison of the estimated temperatures with the measured fild data gives satisfactory results.

  • A Study on Design Method for strengthening of Existing Concrete Structures using Advanced Reinforcing Materials

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)

    Project Year :

    1996
    -
    1997
     

    UEDA Tamon, HATTORI Atsushi, MUTSUYOSHI Hiroshi, NAKAMURA Hikaru, SATO Yasuhiko, SHIMURA Kazunori

     View Summary

    This study is carried out to develop the design method for strengthening of exsisting concrete structures using FRP sheets and FRP tendons. Results in this study are summarized on the following three points ; (1)Long term properties of reinforcing materials, (2)Ultimate capacity and deformation of concrete members retrofitted with FRP sheet, (3)Ultimate capacity and deformation of concrete structures retrofitted with FRP tendons.
    (1) Long-term Properties of Reinforcing Materials
    ・The relaxation ratio represents the natural characteristics of each FRP tendon and varies in proportion to the logarithm of time throughout the entire loading time range.
    ・The tensile strength and bond strength of FRP sheet were not reduced even after FRP sheet is soaked in 10% sulfuric acid solution for six months.
    (2) Ultimate Capacity of Deformation of Concrete Members Retrofitted with FRP Sheets
    ・It was clarified how concrete strength, and stiffness of FRP sheets affect the bond mechanism of FRP sheet. The bond strength equation was proposed.
    ・When peeling of FRP sheet which is attached to a lower face in a beam as flexural reinforcement does not occur, the bending capacity and deformation of the beam can be predicted by the layr-by-layr procedure.
    ・For failure mode with peeling of FRP sheet along a shear crack, the model of predicting the shear reinforcing effect of FRP sheet was proposed.
    (3) Ultimate Capacity and Deformation of Concrete Structures Retrofitted with FRP Tendons
    ・The flexural behavior of externally prestressed beams can be estimated by a precise calculation method considering the compatibility of deformations and changes in location of cables.
    ・The ultimate strength of FRP tendons at deviators becomes less then the uniaxial tensile strength. The rate of reduction differs for different type of FRP tendons.
    ・When a cable tensile force was within the range of 40 to 50% of the nominal breaking load for AF rope, failure did not occur during the the 2,000,000-cycle loading.

  • Calculational Unified Theory for Calculation of Shear Strength of Linear and Planar Members

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

    Project Year :

    1996
    -
    1997
     

    KAKUTA Yoshio, SATO Yasuhiko, FURUUCHI Hitoshi, UEDA Tamon

     View Summary

    In this study four topics are discussed. The major results obtained are as follows.
    1) Effective Width for Shear Failure of RC Deep Slabs
    The effective width to the shear capacity of RC deep slabs was discussed from the experimental results. The effect of the length of loading plate on the effective width is larger than that of the supporting plate. If it is considered that the effective width is related to the swell of the compressive concrete strut formed between the loading and supporting plates, the shear span ratio is a factor of great importance to the swell.
    2) Effect of Shear Reinforcement on Local Shear Failure of RC Slabs
    For one way and cantilever RC slabs, the shear reinforcing effects were experimentally investigated. In case of the slabs with a punching shear failure, the shear capacities increase with shear reinforcement. In case of the slabs with a beam shear failure, the capacities increase a little. The strain of the shear reinforcement starts to increase suddenly at a certain load, however, the strains do not reach its yield strain when the slabs reaches its ultimate state.
    3)Modeling for Dowel and Bond Actions of Longitudinal Bars in Shear Failure of RC Members
    Modeling for the longitudinal bars in a shear resisting mechanism was conducted. The cracking along a longitudinal bar is caused by a combined effect between the dowel and the bond actions. The deformation of the bars can be described by modeling the surrounding concrete as an elasto-plastic spring. The criteria of the cracking is related to a vertical and a slip displacements of the bars.
    4)Analytical Study on Axisymmetrical RC Slabs
    An effect of the shear reinforcement on the shear capacity of axisymmetrical RC slabs can be described by using a nonlinear finite element analysis. The effect of the tensile and shear reinforcing bars on the member stiffness is clarified by the analysis.

  • 連続繊維補強コンクリート梁部材の曲げ及びせん断疲労強度式の構築

    日本学術振興会  科学研究費助成事業 奨励研究(A)

    Project Year :

    1996
     
     
     

    佐藤 靖彦

     View Summary

    本研究において、連続繊維補強コンクリートはりのせん断疲労強度に関する実験及び解析的な検討を行った。まず、実験的検討により得られた主な知見を以下に示す。
    (1)せん断補強筋を持たない連続繊維補強コンクリートはりのせん断疲労強度は、鉄筋コンクリートはりに対して提案されている疲労強度式により評価できる。
    (2)せん断補強筋に連続繊維補強材を用いたはりにおいて、繰返し回数の増加に対するせん断補強筋の歪み及びひび割れ幅の増加割合は、鉄筋コンクリートはりに対する予測式により評価できる。
    以上が、実験的検討により得られた結論である。すなわち、繊維と直角方向の剛性が繊維方向の剛性に比べ極端に小さいことによる付着の劣化はほとんど認められず、従来の鉄筋コンクリートはりの疲労強度式に基づき連続繊維補強コンクリートはり部材の疲労強度を評価できるのである。ただし、本研究では、曲げ成形部の疲労破断に関しては検討できておらず今後の課題として残る。
    一方、解析的な検討により得られた主な知見を以下に示す。
    (1)斜めひび割れ発生荷重が繰返し回数とともに低下することを解析的にシミュレートできる手法を構築した。すなわち、静的荷重問題用に開発されているひび割れ発生前及びひび割れ発生基準に繰返し荷重が作用することによる影響を組み入れた構成則を、非線形有限要素解析プログラムに導入し、斜めひび割れ発生荷重が繰り返し回数とともに低下する現象を評価することを可能とした。
    (2)解析の妥当性を確認するために、本実験結果と比較した結果、的確に予測できることが明らかとなった。今後は、ひび割れ発生後の構成則に繰返しの影響を考慮し、部材の疲労寿命をも解析的に予測できるようにする必要がある。

  • Mechanical Behavior of Shear Connector

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)

    Project Year :

    1995
    -
    1996
     

    UEDA Tamon, SATO Yasuhiko, FURUUCHI Hitoshi

     View Summary

    Shear connector should be placed to assure the composite action between core concrete and skin steel plates in sandwich structures. The code for design of steel-concrete sandwich structures proposed by JSCE specifies how to arrange shear connectors considering its capacity for transferring shear force. However, the effects of existence and deformation characteristics of shear connector on member capacity, especially shear capacity, have not been clarified yet. In this study, having constitutive laws for finite element analysis of sandwich members in our mind, it was aimed to develop a mechanical model for prediction of deformation and capacity of shear connectors. The type of shear connector is shaped steel shear connector. The followings are the conclusions.
    (1) A series of test for steel plates without shear connector indicated that there was a linear relation between capacity of shear force transfer and confining force and that the capacity of shear force transfer was reduced by 20 to 30% putting lubrication oil on the plate.
    (2) Finite element analysis in which the part with shear connectors and the part between shear connectors were modeled differently as link elements expressing relationship between transferred shear force and slip could predict the deformation and ultimate capacity of open sandwich beams.
    From a series of test in which height of shear connector was a parameter the shear connector was modeled as a cantilever together with surrounding concrete. The stiffness of the cantilever was found to be dependent on the height of shear connector, the transferred shear force and the confining force in the surrounding concrete. The transferred shear force at a sudden reduction of the stiffness could be modeled as well.

  • 連続繊維補強材の局部応力に対する破壊基準の構築

    日本学術振興会  科学研究費助成事業 奨励研究(A)

    Project Year :

    1995
     
     
     

    佐藤 靖彦

     View Summary

    本研究では、はり部材中の連続繊維補強材の局部応力による破壊基準を、(1)連続繊維補強材直線部の斜めひび割れとの交差部での破断、(2)連続繊維補強材曲げ成形部での破断、に分けて検討した。以下にそれぞれに対して得られた知見を示す。
    (1)直線部の破壊基準
    連続繊維補強材直線部の破壊基準を明らかにすることを目的として、連続繊維補強材に引張力とせん断力を作用させたモデル供試体を用いた実験及び3次元非線形有限要素解析を行った。その結果、連続繊維補強材直線部の破壊モードは、曲げ支配型とせん断力支配型の2つに分けて考えることができることが明らかとなった。すなわち、曲げ支配型の場合、連続繊維補強材は一軸引張歪みに達したときに破断し、せん断支配型の場合には一軸引張歪みに達する前に限界のせん断歪みに達し破壊する。特に、炭素繊維補強材の限界せん断歪みはアラミド繊維補強材よりも非常に小さいことが明らかとなった。
    (2)曲げ成形部の破壊基準
    曲げ成形部における破壊基準を明らかにする目的で、はり部材中のせん断補強筋をモデル化した実験及び2次元非線形有限要素解析を行った。その結果、曲げ内半径が小さなものほど、曲げ成形部強度が小さく、特に、一軸引張強度に対する曲げ成形部強度との比、すなわち強度低下率は、アラミド繊維補強材に比べ炭素繊維補強材の方が大きいことが実験的に明らかとなった。有限要素解析より、曲げ内半径が小さなものほど応力集中率が大きくなることが明らかとなり、その結果、曲げ内半径が小さなものほど曲げ成形部強度が小さくなるものと考えられた。また解析において、一軸引張歪みに達したときに破断するとした破壊基準を用いた場合、本解析は、アラミド繊維補強材に対しては実験値を精度よく評価できたが、炭素繊維補強材に対しては実験値より曲げ成形部強度が大きくなる傾向にあった。これは、直線部同様、一軸引張歪みに達する前に限界のせん断歪みに達し破断しているものと考えられた。

▼display all

Specific Research

  • モニタリングに基づくコンクリート橋上部構造の残存耐力評価

    2021  

     View Summary

     本研究では,FBGセンサから得られたひずみ挙動と3次元有限要素解析結果を比較することで,橋梁の全体モデルに対して車両荷重と温度と風の影響を再現できる作用のモデル手法を見出した.この方法を用いれば累積損傷度を把握できる.また,サンプリングカメラではなく,一般的な一眼レフカメラを用いたモアレ解析による変位計測の精度を明らかにした.桁の変形を含む床版の面外方向変位は,床版の損傷度指標としては適していないこと,面内変形の形状は,残存耐力を評価できる可能性が高いことを見出した.

  • コンクリート床版の外力・状態・性能評価システム

    2020  

     View Summary

    道路橋コンクリート床版の任意の時点における残存耐力と余寿命を,外観損傷度から予測できる手法を開発することの意義は大きい.その実現には,外力と損傷度と寿命予測を関連づける必要があり,そのためには,コンクリート床版の破壊形式を整理しなければならない.本研究において,コンクリート床版の破壊形式として,せん断圧縮破壊形式,土砂化後の押抜き破壊形式,鉄筋降伏・破断形式の3つと形式が存在することを明らかにし,上限荷重と損傷度と寿命の関連付けを可能とした.

  • コンクリート系床版の疲労寿命予測法の開発

    2019   竹田京子

     View Summary

     本研究では,輪荷重走行試験の実験結果に基づき,せん断耐力式とS-N曲線式によるRCおよびPC床版の疲労寿命予測法を開発するとともに,接合部を有するプレキャストPC床版の疲労耐久性評価に関する検討を行った.開発した疲労寿命予測式(提案式)は,RCおよびPC床版の疲労寿命を精度良く予測できることを実験結果との比較から示した.さらに,接合部の疲労寿命予測においては,継手鉄筋の引張力によりコンクリート内部に導入される圧縮力が主鉄筋の拘束を高め,付着力が向上することで静的な耐力が向上する機構を見出し,この耐力向上効果を提案式に考慮することで,接合部の疲労寿命の予測精度が向上することを示した.

  • 移動輪荷重を受ける道路橋RC床版の疲労設計法

    2018   竹田京子

     View Summary

     道路橋の鉄筋コンクリート床版(RC床版)は,交通荷重,すなわち移動輪荷重を繰返し受けるため,疲労に対する設計が欠かせない.しかし,その合理的な疲労設計法は存在しない.そこで,過去に複数の研究機関において行われた輪荷重走行試験結果を活用し,せん断抵抗機構および破壊機構に基づいたRC床版の疲労寿命予測式を開発した.しかし,その式はその適用範囲が限定されており,適切に評価できない実験結果が存在する. そこで本研究では,過去に開発したRC床版の疲労寿命予測式を拡張し,載荷速度と支持条件が疲労寿命に及ぼす影響を明らかにするとともに,階段状に変化する移動輪荷重下におけるRC床版の疲労寿命予測を可能とした.

 

Syllabus

▼display all