Updated on 2023/02/06

写真a

 
HOKIBARA, Tomoyo
 
Scopus Paper Info  
Paper Count: 0  Citation Count: 0  h-index: 2

Citation count denotes the number of citations in papers published for a particular year.

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

Concurrent Post

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

Research Institute

  • 2022
    -
    2024

    Waseda Research Institute for Science and Engineering   Concurrent Researcher

Education

  • 2017.04
    -
    2020.03

    Waseda University   Graduate School of Creative Science and Engineering  

  • 2013.04
    -
    2015.03

    Waseda University   Graduate School of Creative Science and Engineering  

  • 2009.04
    -
    2013.03

    Waseda University   School of Creative Science and Engineering  

Research Experience

  • 2021.04
    -
    Now

    Waseda University   Faculty of Science and Engineering

  • 2015.04
    -
    2021.03

    株式会社竹中工務店   設計部

Professional Memberships

  •  
     
     

    日本火災学会

  •  
     
     

    日本建築学会

 

Research Areas

  • Architectural environment and building equipment   Fire safety / Physical behaviors of materials and structures in disasters / evacuation behaviors / wooden structures / Utilization and preservation historical buildings

Research Interests

  • 歴史的建築物

  • 防耐火研究

  • 木造建築

  • 建築防災

Papers

  • MINIMIZATION OF THE VOLUME OF THE WOOD-BASED BARRIER FOR 2-HOUR FIREPROOF WOODEN BEAM:Bench-scale and full-scale furnace tests on fire-retardant barrier of Japanese cedar glulam

    SAIYOSHI Taiga, HASEMI Yuji, HOKIBARA Tomoyo, AOYAMA Gen, TAKASE Ryo, KAMIKAWA Daisuke, SUZUKI Jun-ichi

    Journal of Environmental Engineering (Transactions of AIJ)   86 ( 779 ) 1 - 11  2021  [Refereed]

     View Summary

    <p> Design of 2-hour fireproof wooden beam protected by wood-based fire protection barrier is studied. The lightness of the structure, one of the most important features of the wooden construction superior to the reinforced concrete and steel constructions, becomes more significant as the buildings become taller. The study aims at minimizing the total weight of the fire protection barrier, which is composed of the Phosphorus fire-retardant treated wood layer and, if necessary, the surface sacrificial layer and is notably heavier than the load-bearing part, assuming Japanese cedar as the material. Through review of previous studies, it has been expected that the sacrificial layer with the universal optimum thickness for Japanese cedar(25mm) can substitute for the 1.5 times heavier treated wood of the same thickness and the bottom and the lower corners of the beam may need thicker barriers than the vertical sides for possible dropping of the sacrificial layer during fire heating and the increase of the relative heating surface especially at the corners.</p><p> The following three series of furnace tests are conducted to clarify the necessary performance and thickness of the treated wood for the barrier on the vertical sides, the bottom and the lower corners.</p><p> Test I) Bench-scale test on specimens reproducing the barriers of vertical side part in order to explore the suitable treatment and thickness of the treated wood barrier for the 2-hour fireproof wooden beam</p><p> Test II) Unloaded full-scale test on an entire beam cross section to verify carbonization of the bottom and lower corners</p><p> Test III) Bench-scale test on specimens reproducing a lower corner with different treated layer thicknesses</p><p> Test I has revealed the followings:</p><p> ①Whether the wood within 25mm from the surface is treated or not, there is no influence for the achievement of the 2-hour fireproof performance. Use of 25mm thick of sacrificial layer is effective to reduce the weight of the total assembly.</p><p> ②The target amount of the fire-retardant agent of 120kg/m3 is found to be not enough to suppress glowing combustion against the 2-hour ISO834 standard fire heating, while sufficient performance is demonstrated for 180kg/m3. The test result suggests the effectiveness of the fire-retardant treatment as the barrier for 2-hour fireproof performance would reach the upper limit at around 150kg/m3.</p><p> Test II has revealed that:</p><p> ①Using an extra lamina(25mm thick) treated wood for the bottom is effective to prevent the dropping of the charred protection layers during the fire heating and secure the 2-hour fireproof performance.</p><p> ②The lower corners can be critical for the achievement of any design fireproof performance, due to the largest relative heating surface area during the fire heating and the reduction of the heat exchange performance after the heating by the dropping of the edge surfaces. Design of the lower corners is found to be the key for the fireproof performance of wood-based fire protection layers.</p><p> The result of the Test III suggests the following specification as the minimum weight 2-hour fireproof wooden beam with totally wood-based fire protection: i) 25mm thick sacrificial wood, ii) 75mm thick treated wood on the vertical sides and 100mm thick treated wood on the bottom as fire barriers, and iii) target amount of Phosphorus fire retardant agent of 180kg/m3.</p>

    DOI CiNii

    Scopus

    2
    Citation
    (Scopus)
  • Control of the Self-extinguishability of Wood-based Protection Layers for Wooden Fireproof-Structural Elements

       2020.03  [Refereed]

    Authorship:Lead author

  • UNIVERSAL SACRIFICIAL-LAYER THICKNESS INDEPENDENT OF DESIGNED FIRE-RESISTANCE TIME FOR WOODEN FIREPROOF-STRUCTURAL-ELEMENTS:Bench-scale tests using fire-retardant Japanese cedar laminated-lumber in barrier

    HOKIBARA Tomoyo, HASEMI Yuji, SAIYOSHI Taiga, TAKASE Ryo, KAMIKAWA Daisuke, YASUI Noboru, MIYABAYASHI Masayuki

    Journal of Environmental Engineering (Transactions of AIJ)   84 ( 761 ) 607 - 614  2019.07  [Refereed]

     View Summary

    <p> The concept of fireproof construction in Japanese building regulation was redefined in 2000 to enable large wood based buildings to sustain permanent load bearing capability even after enduring the effects of a fire. The target of this study is the fireproof layered structure composed of:</p><p> a) a load bearing part at the core</p><p> b) a barrier (fire-retardant impregnated wood)</p><p> c) a sacrificial layer</p><p> This type of layered structure is the furthest behind in terms of development in respect to other types of wood-based fireproof construction.</p><p> The authors clarified the condition of ability to self-extinguish, to the point of no further glowing combustion, after the fire heating of this test target. In the previous report, by designing the thickness of the sacrificial layer so as to reach the pyrolysis temperature of the fire retardant agent during heating, the fire retardant performance of the barrier can be minimized. From the pyrolysis temperature of the fire retardant agent, the sacrificial layer thickness may be increased in proportion to the fire resistance time.</p><p> However, if there is an optimum thickness of the sacrificial layer at each fire resistance time then the sacrificial layer, which is exposed to fire heating shorter than the designed fire resistance time, cannot self-extinguish. Therefore, the following 2 tests were conducted in order to clarify that the sacrificial layer thickness does not depend on the designed fire resistance time.</p><p> (1) Bench-scale tests were conducted using small specimens modeling the wooden fireproof structural elements in order to confirm whether they self-extinguished when they were heated for a time shorter than the designed fire resistance time.</p><p> (2) From series (1), it was estimated that 25mm is the optimum sacrificial-layer-thickness independent of the designed fire resistance time (the specification had fire resistance for 1 hour). Therefore, the specification was confirmed through further testing that it self-extinguished even when exposed to heating for less than 1 hour.</p><p> From these tests, the following conclusions can be drawn.</p><p> 1. The sacrificial layer, with a thickness designed according to the fire resistance time, may not be self-extinguishing in some cases if the heating time is shorter than the designed fire resistance time. The reason are as follows. First, since the sacrificial layer is too thick to allow the heat to penetrate into the barrier layer by the end of heating, meaning the barrier layer will not reach pyrolysis temperature. Second, the sacrificial layer is kept hot by the carbonized layer on the surface, meaning heat loss on the surface does not cause it to self-extinguish.</p><p> 2. Regardless of the heating time and type of the fireproof performance, the optimum thickness range of surface layer is 25 mm or less. In the range where carbonization is completed during heating, fire proof performance is not greatly affected without using fire retardant wood as the sacrificial layer. Therefore, an optimum design method for wooden fireproof structural elements is to set the sacrificial layer thickness to the upper limit value so that it does not burn by glowing combustion after the end of heating.</p>

    DOI CiNii

    Scopus

    3
    Citation
    (Scopus)
  • Optimization of the wood-based fire protection layer - An engineering approach to the design of fireresistive building elements based on a sacrifice-layer concept

    Tomoyo Yamaguchi, Yuji Hasemi, Daisuke Kamikawa, Jun Ichi Suzuki

    WCTE 2018 - World Conference on Timber Engineering    2018  [Refereed]

     View Summary

    Strategy for the development of wooden structural elements with self-extinguishing performance based on a sacrifice-layer concept was studied through a series of bench scale tests. The typical structural elements composed of two layers and structural part: the first is sacrifice layer (chemically untreated wood), the second is fire barrier (fire retardantand untreated load bearing wood. It has revealed that the thickness of sacrifice layer is important to achieve self-extinguishment of timber elements. All the sacrifices layers should be burnt and glow at around the end of the heating period following the ISO 834 standard curve. It has resulted in the development of Japanese-cedar based 1-hour fire-resistive beam. only with small test apparatuses available almost everywhere, demonstrating its advantage for the technical development in the districts not accessible to large furnaces.

  • Engineering approach to the design of wooden fireproof structural elements based on the sacrifice-layer concept: Optimum design of the wood-based protection layers using bench-scale tests

    Tomoyo Yamaguchi, Daisuke Kamikawa, Yuji Hasemi, Noboru Yasui, Ryo Takase, Masayuki Miyabayashi, Jun Ichi Suzuki

    Journal of Environmental Engineering (Japan)   81 ( 730 ) 1065 - 1074  2016.12  [Refereed]

     View Summary

    Strategy for the development of wooden fireproof structural elements based on the sacrifice-layer concept through bench-scale tests is studied through a series of bench scale tests on the design composed of sacrifice layer (chemically untreated wood), barrier (fire retardant treated wood) and loadbearing part (untreated wood). It has revealed importance of the design of the sacrifice layer to reach the glowing combustion temperature at around the end of the heating for the achievement of self-extinguishment. It has resulted in the development of Japanese-cedar based l"hour fireproof beam only with small test apparatuses available almost everywhere, demonstrating its advantage for the technical development in the districts not accessible to large furnaces.

    DOI

  • Development of wood-based fireproof buildings in Japan

    Yuji Hasemi, Naoyuki Itagaki, Tomoyo Yamaguchi

    WCTE 2016 - World Conference on Timber Engineering    2016

     View Summary

    This report gives a summary review on the state-of-the-art and a scope of the development of woodbased "fireproof construction" and its application to real buildings in Japan. It includes review of the administrative background for the promotion of the use of wood in buildings, state of the art review on the technical aspects of wood based fireproof buildings, and discusses the needed research and actions for the further promotion of wood based fireproof buildings in Japan.

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Misc

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Industrial Property Rights

  • 被覆基材及びその製造方法

    Patent

Works

  • 切断の諸相01 Wonder the oneroom

    伯耆原洋太, 伯耆原智世  Architectural work 

    2020.05
    -
    Now

  • Ring on the Green

    Yota, Tomoyo Hokibara  Architectural work 

    2022.05
    -
     

Awards

  • Grand Prize

    2022.12  

  • 優秀賞

    2022.09   公益財団法人 住宅リフォーム・紛争処理支援センター   第39回住まいのリフォームコンクール

  • 大会学術講演会 若手優秀発表賞

    2018.10   日本建築学会   2時間耐火性能を有する燃え止まり型木質耐火構造に関する研究(その1)適正な燃えしろ層厚さの把握

    Winner: 伯耆原智世

  • 大会学術講演会 若手優秀発表賞

    2015.09   日本建築学会   燃え止まり型木質耐火構造部材の工学的設計法に関する研究:その2実大部材への適用及び数値的設計手法の開発可能性の検証

    Winner: 山口智世

  • 早苗賞

    2015.03   早稲田大学   燃え止まり型木質耐火構造部材の工学的設計法に関する研究 –木材の自消条件から見た燃えしろ・燃え止まり層の最適設計の検討

    Winner: 山口智世

  • 優秀卒業論文賞

    2013.08   日本建築学会   火災加熱される木質部材の熱分解・燃焼性状のモデル化に向けた基礎研究

    Winner: 山口智世

  • UIA2011東京大会設計競技 JIA賞銅賞・茨城賞

    2011.09   国際建築家連合(UIA)、日本建築家協会(JIA)   Kasumigahara Southern Coastal Region "Smart Region Plan"

    Winner: 山口智世

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Specific Research

  • 火災加熱される木質構造部材の力学的性能予測の実験的研究‐火災後の継続使用に向けて

    2022  

     View Summary

    耐火・準耐火構造による木質耐火構造部材の開発に向けて、特に加熱終了後の燃え進みを予測するための木造の高温時の熱物性や力学的性能の把握を目的とした基礎研究である。木材は樹種、密度、含水率等の多様な物性によってその力学的性能が変化することが知られている。更に、加熱された木材は、その物性が温度帯によって変化し、温度帯によっては不可逆的な物性の変化が起こる。そこで、木材を構造部材として利用する場合の防耐火性能を把握するために、耐火構造部材として利用されるスギ、カラマツを対象として、木材の異方性や接着面が熱水分移動に与える影響を小試験体で把握する基礎実験を行い水分が移動しやすい条件を明らかにした。

  • 超高層耐火木造における材積最小化に向けた研究

    2021  

     View Summary

    高層木造を達成するには高度な耐火性能が要求される。従来では、2、3時間と要求耐火時間が長くなるほど、被覆層を厚する設計法が一般的であるが、被覆層の肥大化は、可燃物を増やすことになり、構造面の他、防耐火上でも不利になりかねない。そこで、部材の材積最小化に向けて、木質構造部材の一部を模した小試験体を用いて断面構成の把握を行い、15階建て以上を建築可能な3時間耐火性能を確保できる部材断面構成の見通しを得た。更に、木材内部の熱水分移動は、防耐火性能に大きく影響するため、木材の異方性が熱水分移動に与える影響を小試験体で把握する基礎実験を行い、繊維、接線、半径方向の順に水分が移動しやすいことを明らかにした。

 

Syllabus

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Media Coverage

  • ABITARE 621/ Itary

    Newspaper, magazine

    An industrial-style studio-home in Tokyo  

    Cover, pp26-35  

    2023.01

  • I'm home no.120

    Newspaper, magazine

    株式会社商店建築社   四つの用途をもつワンルームの住まい  

    2022.11

  • 理想の暮らしをかなえるリビングの本

    Newspaper, magazine

    トーソー出版  

    2022.11

  • relife+ premium

    Newspaper, magazine

    扶桑社  

    2022.09

  • my HOME 2022.APR / TAIWAN magazine

    Newspaper, magazine

    2022.04

  • LIVES living &Lifestyle Magazine

    Newspaper, magazine

    Cover  

    2020.11

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