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Last Updated :2024/09/13

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Master

Affiliation (Master)

  • Faculty of Engineering　Division of Architecture　Research Group of Structural Engineering and Materials

Affiliation (Master)

  • Faculty of Engineering　Division of Architecture　Research Group of Structural Engineering and Materials

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Profile and Settings

Profile and Settings

  • Name (Japanese)

    Matsui

  • Name (Kana)

    Ryota

  • Name

    201601008716890575

Achievement

Research Interests

  • Structural Experiment   Numerical Simulation   Steel Structure   Building Engineering   

Research Areas

  • Social infrastructure (civil Engineering, architecture, disaster prevention) / Building structures and materials / Steel Structure

Research Experience

  • 2018/10 - Today Hokkaido University Faculty of Engineering, Architectural and Structural Design, Structural and Urban Safety Design Associate Professor
  • 2016/04 - 2018/09 Tokyo Institute of Technology School of Environment and Society, Architecture and Buidling Engineering Dept. Assistant Professor
  • 2011/04 - 2016/03 Tokyo Institute of Technology Graduate School of Engineering, Architecture and Building Engineering Dept. Assistant Professor

Education

  • 2008/03 - 2011/03  Tokyo Institute of Technology  Graduate School of Engineering  Architecture and Building Engineering Dept., Doctoral Course
  • 2006/04 - 2008/03  Tokyo Institute of Technology  Graduate School of Engineering  Architecture and Building Engineering Dept., Master Course
  • 2002/04 - 2006/03  Tokyo Institute of Technology  School of Engineering  Architecture and Building Engineering Dept.

Committee Memberships

  • 2020/04 - Today   Japanese Society of Steel Construction   Committee for Journal of Steel Construction Engineering
  • 2019/04 - Today   Architectural Institute of Japan   Subcommittee for the Revision of Recommendation and Fabrication of Light Weight Steel Structures
  • 2020/04   Japanese Society of Steel Construction   Committee on JSSC Journal

Awards

  • 2019/05 Architectural Institute of Japan AIJ Book Award 2019
     Buckling-Restrained Braces and Applications 
    受賞者: Toru Takeuchi;Akira Wada;Ryota Matsui;Sitler Ben;Lin Pao-Chun;Sutcu Fatih;Hiroyasu Sakata;Qu Zhe
  • 2013/08 Architectural Institute of Japan Encouragement Prize
     
    受賞者: MATSUI Ryota
  • 2012/02 Tokyo Institute of Technology Seiichi Tejima Doctoral Dissertation Award
     
    受賞者: MATSUI Ryota
  • 2011/11 Japanese Society of Steel Construction 19th Symposium, Best Presentation Award
     
    受賞者: MATSUI Ryota
  • 2011/03 Center for Urban Earthquake Engineering Best Presentation Award
     
    受賞者: MATSUI Ryota

Published Papers

  • 寺澤友貴, 石橋洋二, 田中陽樹, 横山亮, 水野紘貴, 竹内徹
    日本建築学会構造系論文集 Vol. 87 (No. 802) 2022/12/10
  • Yuta FUKE, Taichiro OKAZAKI, Ryota MATSUI
    AIJ Journal of Technology and Design 28 (70) 1236 - 1241 1341-9463 2022/10/20
  • Ryota Matsui, Zhang Yiyue, Taichiro Okazaki, Toru Takeuchi
    Lecture Notes in Civil Engineering 216 - 223 2366-2557 2022 [Refereed]
  • Ryota Matsui, Koichi Koizumi, Pao-Chun Lin, Masanobu Iwanaga, An-Chien Wu, Toru Takeuchi, Keh-Chuyan Tsai
    Journal of Structural Engineering 147 (7) 0733-9445 2021/07 [Refereed]
  • Ben Sitler, Toru Takeuchi, Ryota Matsui, Masao Terashima, Yuki Terazawa
    Engineering Structures 213 110482 - 110482 0141-0296 2020/06 [Refereed]
     
    © 2020 The Authors While buckling-restrained braces offer excellent energy dissipation characteristics, their low post-yield stiffness may result in large residual drifts and interstory drift concentration when used in simply supported frames. This paper introduces a new multistage buckling-restrained brace to help mitigate these design challenges. The proposed device features two low yield point (LYP) cores with LY225 and short yield lengths, and one high yield point (HYP) core with SA440B and a longer yield length. In a design level event, the LYP cores dissipate energy, while the parallel HYP core provides an elastic restoring force. At large drifts, the HYP core yields and the device acts similar to a high-capacity, ductile, conventional BRB. A 384 kN specimen was tested at up to 1.5% strain and the individual core contributions recorded using strain gauges attached to the elastic core segments inside the restrainer. The multistage response matched the predicted trilinear backbone, achieving 10 to 20% equivalent damping prior to yielding the HYP core, and a fatigue capacity exceeding three times the AISC 341-16 acceptance criteria. Interaction between the decoupled cores was studied using a 3D finite element model, indicating that minor detailing changes could further improve performance.
  • Fatih Sutcu, Ahmet Bal, Kazuhiro Fujishita, Ryota Matsui, Oguz C. Celik, Toru Takeuchi
    Bulletin of Earthquake Engineering 18 (5) 2389 - 2410 1570-761X 2020/03/01 
    © 2020, Springer Nature B.V. Existing reinforced concrete (RC) buildings designed according to outdated codes may lack sufficient strength, stiffness or ductility to meet the seismic performance criteria of current codes. To enhance the system stiffness and re-centering capability, an elastically designed supplementary steel frame (SF) is installed in parallel with the BRBs. Near full-scale cyclic tests are conducted on such retrofit schemes for performance evaluation. The retrofitted specimens showed stable hysteretic behavior up to the retrofit target story drift of 1/150 as proposed in the Japanese seismic regulations. Tests demonstrate that the proposed system is feasible and increases both strength, ductility, and damping to an adequate seismic performance level while the elastic steel frame is effective in providing post-yield stiffness and re-centering capability even when the RC frame is subjected to moderate inelasticity. Special emphasis is placed on the composite behavior of RC members and SF. A simplified composite interaction model is proposed and results from the developed model show good agreement with the experimental data. Ductility demands are shown to concentrate in the BRBs as per the design intent.
  • Sho FUKUTOMI, Taichiro OKAZAKI, Ryota MATSUI, Tetsuhiro ASARI
    Journal of Structural and Construction Engineering (Transactions of AIJ) 85 (778) 1555 - 1563 1340-4202 2020 [Refereed]
  • Pao-Chun Lin, Toru Takeuchi, Ryota Matsui
    Engineering Structures 194 441 - 457 0141-0296 2019/09 [Refereed]
     
    © 2019 The outrigger system is an effective solution in mitigating seismic responses of core-tube-type tall buildings by mobilizing the axial stiffness of the perimeter columns. The concept of damped-outrigger has been proposed which introduces dampers in the outrigger system to dissipate seismic energy. This study investigates the seismic behavior of a damped-outrigger system incorporating buckling-restrained brace (BRB-outrigger). The outrigger effect combined with the energy dissipation mechanism of the buckling-restrained brace (BRB) effectively reduce the seismic response of the building. This study proposes the methods to evaluate the inelastic seismic response of structures with multiple damped-outriggers based on a spectral analysis (SA) procedure. For the structure with BRB-outriggers, the optimal outrigger elevations, and the relationships between the axial stiffness of the BRB, the axial stiffness of the perimeter column, and the flexural rigidity of the core structure in order to minimize the seismic response are the primary research objectives of this study. Analytical models with building heights of 64 m, 128 m, 256 m, and 384 m are used to perform the SA and the nonlinear response history analysis. This study concludes with a design recommendation for preliminary design purposes.
  • Ryota MATSUZAKI, Ryota MATSUI, Toru YOSHIKAWA, Kentaro MINOWA, Toru TAKEUCHI
    Journal of Structural and Construction Engineering (Transactions of AIJ) 84 (763) 1305 - 1313 1340-4202 2019 [Refereed]
     
    © 2019 Architectural Institute of Japan. All rights reserved. A friction damper is one of useful displacement-depending energy dissipation devices; however, it is necessary to obtain the mechanical characteristics of each friction material through various experiments. Also the conventional design methods obtaining the optimal damper stiffness distribution to adjust response story drift angle to target values is inconvenient for friction dampers. In this paper, dynamic loading tests for friction dampers with different kinds of materials are conducted, and characteristics of each material are compared. Further, an alternative method to design the response-controlled structures with optimal friction damper distributions based on the strength index is proposed, and their validity is confirmed.
  • Ryota MATSUI, Jun ARIGA, Kunihiro MORISHITA, Motoki KATO, Toru TAKEUCHI
    Journal of Structural and Construction Engineering (Transactions of AIJ) 84 (761) 973 - 982 1340-4202 2019 [Refereed]
     
    © 2019 Architectural Institute of Japan. All rights reserved. The authors have proposed a phenomenological fiber model to simulate local buckling behavior of steel structural components in building frames. This phenomenological model captures development of the plastic strain localization of steel columns subjected to high axial load. This study presents the accuracy of the phenomenological fiber models applied to truss members. As a result, the phenomenological fiber model simulates the force-deformation relationship of the truss members including local buckling. This phenomenological fiber model is used for numerical simulation of a braced steel frame with incremental dynamic analysis to investigate the effect of local buckling on the ultimate seismic performance.
  • Ryota MATSUI, Shukai HASHIMOTO, Toru TAKEUCHI
    Journal of Structural and Construction Engineering (Transactions of AIJ) 84 (760) 863 - 873 1340-4202 2019 [Refereed]
  • Ryota MATSUI, Katsuto TOMOEDA, Ben SITLER, Toru TAKEUCHI, Saki MIHARA, Yuma HOASHI
    Journal of Structural and Construction Engineering (Transactions of AIJ) 84 (758) 563 - 573 1340-4202 2019 [Refereed]
     
    © 2019 Architectural Institute of Japan. All rights reserved. Global out-of-plane stability of buckling-restrained braces is often governed by yielding of the neck. The authors previously proposed a method9) to evaluate this buckling mechanism, including the gusset rotational stiffness, connection length and neck - restrainer flexural continuity. While the proposed method has shown good agreement with experimental and numerical studies, this paper revisits a key assumption in the derivation, where the neck is modelled as an elasto-perfectly plastic hinge. Detailed FEM studies of a chevron BRB experiment with a range of gusset and framing boundary conditions are conducted, and an inelastic buckling model inspired by Shanley’s theory introduced.
  • Hiroaki Harada, Naoki Iriguchi, Yuki Terazawa, Ryota Matsui, Yoshihiro Yamazaki, Hiroyasu Sakata, Toru Takeuchi
    J. Struct. Constr. Eng., AIJ 84 (755) 51 - 59 1340-4202 2019/01 [Refereed][Not invited]
     
    © 2019 Architectural Institute of Japan. All rights reserved. In our previous paper, the static rigidity and the flexural strength at the joint of the lattice shell with the timber steel hybrid connection were clarified by static experiments and their effect on the buckling behavior of the entire roof was revealed by elastic buckling analysis. Here we examine the influence of the rotational stiffness of the connections on natural oscillation and earthquake response characteristics. Also the accuracy of the response spectrum evaluation using CQC method and the equivalent static seismic load are verified, followed by a simplified evaluation method proposal for the effect of rotational stiffness at connections.
  • Yuki Terazawa, Shogo Inanaga, Ryota Matsui, Toru Takeuchi
    J. Struct. Constr. Eng., AIJ 83 (754) 1789 - 1799 1340-4202 2018/12 [Refereed][Not invited]
     
    © 2018 Architectural Institute of Japan. All rights reserved. Large numbers of structural and non-structural components in steel roof gymnasiums with RC substructures were damaged in the past earthquakes. Particularly in 2016 Kumamoto earthquake, structural component in some space frame roofs experienced serious damages including buckling, post-buckling fracture and fallings, which could have caused serious human damages. This paper presents the damage mechanism of space frame roofs with the effects of cantilevered RC walls based on numerical simulations of member-by-member models considering member buckling and fractures. The numerical simulation results were analyzed by comparison with the actual damages.
  • Seismic performance evaluation of single damped-outrigger system incorporating buckling-restrained braces
    Pao-Chun Lin, Toru Takeuchi, Ryota Matsui
    Earthquake Engineering & Structural Dynamics 47 2243 - 2265 2018/12 [Refereed][Not invited]
  • Tomohiko Kumagai, Genta Roppongi, Jutaro Takahashi, Ryota Matsui, Toru Takeuchi
    J. Struct. Constr. Eng., AIJ 83 (752) 1465 - 1475 1340-4202 2018/10 [Refereed][Not invited]
     
    © 2018 Architectural Institute of Japan. All rights reserved. In recent years, damages such as member buckling and falling of ceilings and lightings have occurred in relatively new gymnasiums. In order to solve these damages, introduction of seismic isolation system to spatial structures is cited. Above all, spherical sliding bearing (SSB) has a characteristic its natural period does not depend on the supported weight. Therefore, SSB is considered to be a seismic isolation system suitable for spatial structures consisting of steel members and having light dead load. From these backgrounds, the seismic response behavior of cylindrical lattice arch roofs supported by SSBs by shaking table tests are investigated.
  • Yusuke Inaba, Yuki Terazawa, Ryota Matsui, Tomohiko Kumagai, Toru Takeuchi
    J. Struct. Constr. Eng., AIJ 83 (751) 1263 - 1272 1340-4202 2018/09 [Refereed][Not invited]
     
    © 2018 Architectural Institute of Japan. Numerous steel roof bearings in RC gymnasia were damaged at the 2011 Tohoku and 2016 Kumamoto Earthquake, mainly due to out-of-plane response of cantilevered RC walls. Although the authors confirmed the reduction effect for seismic response of cantilevered RC walls by friction damper bearings, the transverse response evaluation methods including the roof response are not established. In this paper, using the experimental results of a PTFE sliding bearing, a friction damper bearing, and a rubber sheet bearing, the transverse response of RC walls are analyzed by numerical simulations including effects of the roof response, followed by proposing the evaluation methods.
  • Collapse mechanism of tower-supported steel stack composed of circular hollow sections with large diameter-to-thickness ratio
    Ryota Matsui, Takeshi Nakamura, Akira Imamura, Toru Takeuchi
    J. Struct. Constr. Eng., AIJ 83 (750) 1171 - 1181 2018/08 [Refereed][Not invited]
  • Cyclic loading tests on steel roof bearings and effects on roof responses
    Yusuke Inaba, Yuki Terazawa, Ryota Matsui, Tomohiko Kumagai, Toru Takeuchi
    J. Struct. Constr. Eng., AIJ 83 (751) 1129 - 1137 2018/08 [Refereed][Not invited]
  • Seismic performance and evaluation of controlled spine frames applied in high-rise buildings
    X. Chen, T. Takeuchi, R. Matsui
    Earthquake Spectra 34 (3) 1431 - 1458 2018/08 [Refereed][Not invited]
  • Hiroaki Harada, Shun Nakajima, Yoshihiro Yamazaki, Ryota Matsui, Kenichi Hayashi, Hiroyasu Sakata, Toru Takeuchi
    Journal of Structural and Construction Engineering 83 (746) 577 - 587 1881-8153 2018/04/01 [Refereed][Not invited]
     
    In recent years, creating lattice shell roof structures with timber members are getting popularity due to its light weight and aesthetics: However, the one of their major difficulty is the connection details. In this research, a connection details for a rectangular laminated timber with a T-shaped or H-shaped cross section with lag screws are proposed to maintain flexural rigidity and tolerance of timber single layer lattice shell roofs. Their out-of-plane flexural strength and rotational rigidity of the proposed joint are verified by full-scale experiments, followed by the buckling strength evaluation formulas including the effects of connection stiffness.
  • Kenichi Minowa, Megumi Shibata, Ryota Matsui, Toru Takeuchi, Toshiyuki Ogawa
    Journal of Structural and Construction Engineering 82 (740) 1653 - 1662 1881-8153 2017/10/01 [Refereed][Not invited]
     
    Application of energy dissipation devices for the passive vibration control of truss towers has been recently researched, because these towers were generally designed to resist wind load. However, as the earthquake load requirements increases, these towers are possibly to be damaged by large earthquakes. On the other hand, researchers have developed semi-Active control device that produces any adjustable control force using variable dampers. This paper describes an investigation of applying semi-Active control system to truss towers using variable dampers. First, hysteresis of variable dampers is examined using DDOF system. Second, the semi-Active control system is applied to the truss towers to confirm the seismic response reduction compared with the passive vibration control.
  • Yuki Terazawa, Ryota Matsui, Takeshi Nakamura, Torn Takeuchi
    Journal of Structural and Construction Engineering 82 (739) 1485 - 1495 1881-8153 2017/09/01 [Refereed][Not invited]
     
    It is concerned that a long-duration earthquake in the future generates fatigue fractures in the steel structural components. The authors have investigated the member fracture of axial members including cold-formed circular hollow sections. According to previous study of steel braced frames, it's suggested that more ductile structural components should be applied to a steel structure achieving higher seismic performance. On the other hand, it is needed to develop an aseismic design method of a steel braced frame taking member fracture into account of frequent middle or large earthquakes. In this paper, the interaction of cumulative deformation capacity between a circular hollow section brace with different diameter thickness ratio and a steel frame is investigated for extending basic knowledge of ultimate seismic resistance of steel braced frame, using finite element analysis, experiments including shaking table testing and evaluation of ductility factor.
  • Toru Takeuchi, Masakaze Uchida, Ryota Matsui
    Journal of Structural and Construction Engineering 82 (739) 1339 - 1347 1881-8153 2017/09/01 [Refereed][Not invited]
     
    Although the performance of seismic isolation devices as rubber bearings or dampers have been tested and evaluated through unidirectional input, actual seismic response working on these devices are bidirectional. Recently the performance of high-damping rubber bearings is found to be different from those under unidirectional input, and bidirectional tests for various isolation devices are being carried out. In this paper, bidirectional shaking table tests for SSB (Spherical Sliding Bearing/Friction Pendulum Bearing: FPB) are carried out, and the difference of their response against unidirectional response is researched. Found bidirectional effects are discussed using analytical model taking these effects into account, followed by the studies on the effects on the response of supported superstructures.
  • X. Chen, T. Takeuchi, R. Matsui
    JOURNAL OF CONSTRUCTIONAL STEEL RESEARCH 135 242 - 252 0143-974X 2017/08 [Refereed][Not invited]
     
    A controlled spine frame system consisting of an elastic moment frame, elastic spine frame and concentrated yielding elements is proposed to ensure continuous usability of buildings in the event of an earthquake exceeding the design level. Prior studies have documented the excellent performance of spine frame structures in preventing both the concentration of damage in soft stories as well as in providing self-centering. The current study develops a simplified design method based on equivalent dual multi-degree-of-freedom and single-degree of -freedom representations, discussing the effects of damper yield drift, and stiffness ratios between the elastic moment frame, spine frame, and dampers on the structural response. This design method is validated with a parametric study and optimal ranges of the stiffness ratios are provided.
  • Kazuhiro Fujishita, Ryota Matsui, Fatih Sutcu, Toru Takeuchi
    AIJ Journal of Technology and Design 23 (53) 147 - 152 1881-8188 2017/02/01 [Refereed][Not invited]
     
    On the retrofit of existing sub-standard RC building with buckling restrained braces (BRBs), the insulation of elastic steel frame around BRBs is effective for restraining the residual deformation and the distribution of damage to whole structure. On this paper, the nonlinear hysteresis of steel frame member including the composite effect observed during the previous cyclic loading test is modelled to investigate its influence on the over-all structural response. Also, when the composite effect is unevenly distributed on each retrofit member, the worst distribution case of the composite effect is searched with genetic algorithm on the aspect of seismic performance is investigated.
  • Ryota Matsui, Yusuke Inaba, Toru Takeuchi
    Journal of Structural and Construction Engineering 82 (731) 115 - 122 1881-8153 2017/01/01 [Refereed][Not invited]
     
    1. Introduction: The long period and long duration ground motions of the 2011 Tohoku Earthquake caused large deformations in tall (> 80 m) braced steel moment frames. Many engineers and researchers have claimed the damage observed at the beam-ends in these high-rise buildings. Thus, one of urgent tasks is to develop a simple method for screening vulnerability of the beam-ends in braced steel moment frames. Some researchers have proposed several evaluation methods to capture damages at the beam-ends. In this paper, the validity of those methods is investigated, considering fracture of braces, and a simple is proposed that does not require time consuming time history response analysis. 2. Response of Braced Steel Moment Frames under Long Period and Long Duration Ground Motion: First, an approximately 85 m height building model is created to examine the accuracy of the proposed method for evaluation of the beam-end damage considering the brace fracture. 10 long period and long duration artificial ground motions, scaled to 3 kinds of velocity spectrums: 160, 120, 80 cm/s, and 2 observed ground motions, scaled to the velocity spectrum of Building Code in Japan, are adopted as input ground motions. This analysis suggests that the damage distribution of the beam-ends is similar to the story drift distribution. Observation of previous analysis shows that damage of the beam-ends with a weld access hole is frequently larger than those with no hole. 3. Accuracy of Proposed Damage Evaluation Method by Previous Researcher: The accuracy of a damage evaluation method using Manson-Coffin rule previously proposed by a researcher (Manson-Coffin method) is investigated. Miner's rule is used for the evaluation of the beam-end damage in the method, which is largely consistent with static testing results. Another evaluation method using local strain at a beam-end proposed by the authors is fitted to the Manson-Coffin method to improve the accuracy. 4. Reference Ductility Ratio for Damage Evaluation: The number of cycles at each ductility ratio is required to evaluate the damage of the beam-ends using the Miner's rule. This method involves running a time history analysis program. Several ductility ratios are introduced as a reference to reduce calculation time for the damage evaluation of the beam-end. Damage values of the beam-end calculated by one of the reference ductility ratios are consistent with those by the time history response results within a margin of error of plus or minus 30%. 5. Index for Screening Vulnerability of Beam-ends in Braced Steel Moment Frames: The energy ratio is introduced, defined as the earthquake energy spectrum VE to the maximum velocity spectrum Sv. For RE = 2.0-3.5 and a maximum velocity is close to 160 cm/s, the beam-end fracture is likely. RE is promising an index to determine the damage of the beam-end. 6. Conclusions: This research investigated the damage evaluation of beam-ends in braced steel moment frames during a long period and long duration motion. The results are summarized as follows. 1) The damage distribution of the beam-ends is likely to be similar to the story drift distribution. The damage of the beam-end with a weld access hole is frequently larger than that with no hole. 2) Damage values of the beam-ends calculated by one of the reference ductility ratios are consistent with those by the time history response results with a margin of error of plus or minus 30%. 3) When the maximum velocity is close to 160 cm/s and the RE ranges from 2.0 to 3.5, the beam-ends are likely fracture.
  • Abhilasha Maurya, Matthew R. Eatherton, Ryota Matsui, Steven H. Florig
    JOURNAL OF CONSTRUCTIONAL STEEL RESEARCH 127 54 - 65 0143-974X 2016/12 [Refereed][Not invited]
     
    This paper presents the design and experimental investigation of a miniature buckling-restrained brace (MBRB) which can act as a hysteretic damper to dissipate energy when subjected to inelastic axial deformations. The MBRB is similar to a buckling restrained brace (BRB) with a yielding steel core plate restrained from buckling by a grouted restraining tube. The MBRBs, however, are designed to have shorter lengths, smaller steel core dimensions, and smaller yield capacity as compared to a typical BRB. As a result, careful consideration is required for the detailing at the ends and the stability of the MBRB. Small capacity BRBs can be useful in a range of applications as a primary energy dissipating structural fuse or supplementary axial hysteretic damper in seismic force resisting systems. The design, construction, and testing of six MBRB specimens with nominal axial yield forces between 30 kN and 95 kN are reported. Issues related to global stability of the MBRBs are discussed and a stability criterion to prevent global buckling was adopted to design the MBRB end connection pieces. The MBRBs exhibited cumulative plastic deformations between 181 and 400 times the yield deformation and cumulative plastic strain between 46% and 106%. Conclusions about the behavior and recommendations for the design of the MBRB are presented. (C) 2016 Elsevier Ltd. All rights reserved.
  • Toru Takeuchi, Ryota Matsui, Saki Mihara
    EARTHQUAKE ENGINEERING & STRUCTURAL DYNAMICS 45 (12) 1895 - 1917 0098-8847 2016/10 [Refereed][Not invited]
     
    One of the key limit states of buckling-restrained braces (BRBs) is global flexural buckling including the effects of the connections. The authors have previously proposed a unified explicit equation set for controlling the out-of-plane stability of BRBs based on bending-moment transfer capacity at the restrainer ends. The proposed equation set is capable of estimating BRB stability for various connection stiffnesses, including initial out-of-plane drift effects. However, it is only valid for symmetrical end conditions, limiting application to the single diagonal configuration. In the chevron configuration, the out-of-plane stiffness in the two ends differs because of the rotation of the attached beam. In this study, the equation set is extended to BRBs with asymmetric end conditions, such as the chevron configuration. Cyclic loading tests of the chevron configuration with initial out-of-plane drifts are conducted, and the results are compared with the proposed equation set, which is formulated as a function of the normalized stiffness of the attached beam. (c) 2016 The Authors. Earthquake Engineering & Structural Dynamics published by John Wiley & Sons Ltd. (c) 2016 The Authors. Earthquake Engineering & Structural Dynamics published by John Wiley & Sons Ltd.
  • Toru Takeuchi, Ryota Matsui, Hidetaka Nagaji, Kunihiro Morishita
    Journal of Structural and Construction Engineering 81 (728) 1723 - 1732 1881-8153 2016/10/01 [Refereed][Not invited]
     
    In the heavy plant structures as thermal power plants composed with the braced frame structures, the H-section columns receive bending moment under high axial force ratios. In such conditions the columns is tend to cause local and overall buckling under axial forces and bending moments. It is difficult to express the collapse characteristics of columns under such conditions with multi-spring models because the yield areas distributes not only at the ends of the columns but along the member. However, modeling all such columns as detailed FEM models is still time-consuming and not practical in structural design. To solve such problem, a single-dimensioned macro-member model composed of fiber elements is proposed in this paper. Each element has the hysteresis of local buckling characteristics and hence can express the local and overall buckling phenomena with simple element which can be easily plugged into time-history analyses. The validity of the proposed element is compared with experiments and FEM models with shell elements, followed by the discussions on their accuracies.
  • Kazuhiro Fujishita, Ahmet Bal, Fatih Sutcu, Ryota Matsui, Masao Terashima, Oguz C. Celik, Toru Takeuchi
    Journal of Structural and Construction Engineering 81 (727) 1575 - 1584 1881-8153 2016/09/01 [Refereed][Not invited]
     
    Strength and stiffness of panel and joint in non-diaphragm CHS-column to H-beam connection were experimentally investigated Herein, the panel means the cylindrical stub circumscribed by outer planes of the beam and the column, and the joint means the butt seam between the column wall and the beam end. Two types of specimen were tested: one is an X-shaped frame whose panel is subjected to shear, and the other is a 3-point bending specimen whose panel is free from shear. In result, the joint strength and stiffness are well predicted by the previously proposed formulae irrespective of the existence of shear in the panel, and the panel strength and stiffness are also well predicted by the well known formulae given for diaphragm connections. This suggests that the interaction between panel and joint of the non-diaphragm connection can be ignored in structural design.
  • Ryota Matsui, Yuki Terazawa, Torn Takeuchi
    Journal of Structural and Construction Engineering 81 (727) 1553 - 1563 1881-8153 2016/09/01 [Refereed][Not invited]
     
    The authors have proposed a method to assess local fracture of concentric braced frames under cyclic loading from global member results termed the Direct Local Strain Evaluation Method. In this method there is no need to use detailed member shell models to estimate the strain at the fracture point in the braces. This enables accurate time history response analysis using less computationally intensive stick models, while including the effect of local member fracture. However, up to now, the accuracy of the proposed method has only been validated under static loading. This research validates the proposed method with dynamic numeric and shake table testing. The proposed method is effective in simulating the braced frame response including the brace fracture under dynamic loading.
  • Kazuhiko Narita, Toru Takeuchi, Ryota Matsui
    AIJ Journal of Technology and Design 22 (50) 41 - 46 1881-8188 2016/02/01 [Refereed][Not invited]
     
    In the 2011 Tohoku Earthquake, a large number of school gymnasia suffered damage. One of the most typical damage observed in steel roof gymnasia supported by the RC frame is failure at the anchored connections of steel roof bearings on the RC frame. In this paper, the practical evaluation methods that we proposed in our past papers, of the reaction forces at the anchor connections, of the displacements at the roller bearings, and of the design requirements for the friction dampers, are compared with the time history analysis results.
  • Toru Takeuchi, Michiyasu Yoshida, Masakaze Uchida, Osamu Nishi, Ryota Matsui
    Journal of Structural and Construction Engineering 81 (721) 629 - 637 1881-8153 2016 [Refereed][Not invited]
     
    The seismic response of rack warehouses is known to be reduced by horizontal sliding of 1he warehouse contents, which act as mass dampers. However, in past earthquakes business continuity has been interrupted due to damage from spilling, toppling or falling contents. In this paper, response control using seismic isolation is investigated. Because the total rack weight is constantly changing and tie rack is often loaded at large eccentricities, Spherical Sliding Bearings (SSB) are proposed, which exhibit natural periods independent of the supported weight. Based on numerical and experimental test results undertaken previously, an analytical model is proposed including pressure and velocity dependent friction values. Using He proposed model, the performance of a seismically isolated rack warehouse with variable weight and eccentricity is studied and compared with conventional rubber bearings.
  • Kazuhiro Fujishita, Fatih Sutcu, Ryota Matsui, Tom Takeuchi
    Journal of Structural and Construction Engineering 81 (721) 537 - 546 1881-8153 2016 [Refereed][Not invited]
     
    Damper distribution rule with equivalent linearization method on seismic control retrofit for overseas brittle RC buildings was proposed by die authors. However, tins result is not necessarily proved as optimal. Recently. Genetic Algorithm (GA) is applied to solve numerous kinds of structural optimization problems, mainly in the range of static analysis, hi this paper, the optimization method of damper distribution with GA using elasto-plastic dynamic analysis for multi degree of freedom shear spring model is proposed. By using proposed optimization method, the optimal damper distribution defined as minimum damper distribution satisfying die target stray drift angle for seismic retrofit, is obtained. Finally, comparison of die results with GA and solutions with equivalent linearization method is represented and the effectiveness of proposed damper distribution rule is discussed.
  • Optimal Arrangement of Energy-Dissipating Members for Seismic Retrofitting of Truss Structures
    Toru Takeuchi, Yusuke Kinouchi, Ryota Matsui, Toshiyuki Ogawa
    American Journal of Engineering and Applied Sciences 8 (4) 455 - 464 2015/11 [Refereed][Not invited]
  • T. Takeuchi, X. Chen, R. Matsui
    JOURNAL OF CONSTRUCTIONAL STEEL RESEARCH 114 51 - 65 0143-974X 2015/11 [Refereed][Not invited]
     
    Recently, various controlled rocking systems have been proposed in seismic design to prevent damage concentration and to achieve self-centering against a wide range of input ground motion intensities. However, several obstacles must be overcome before these systems can be applied to actual buildings; for example, the requirement for large, self-centering post-tensioned strands and special treatment at uplift column bases must be addressed. This paper proposes a non-uplifting spine frame system with energy-dissipating members without post-tensioned strands, its self-centering function is achieved by envelope elastic-moment frames. The system is applied to an actual building constructed in Japan. Conventional shear damper and uplifting rocking systems with post-tensioned strands developed in prior studies are also applied to the same building structures, and the performances of the three systems, including damage distribution, energy dissipation, self-centering, robustness against severe earthquakes, and irregular stiffness, are compared and discussed through numerical simulations based on practical design criteria. (C) 2015 The Authors. Published by Elsevier Ltd.
  • Toru Takeuchi, Hitoshi Ozaki, Ryota Matsui, Saki Mihara
    AIJ Journal of Technology and Design 21 (49) 1065 - 1070 1881-8188 2015/10/01 [Refereed][Not invited]
     
    One of the key limits of buckling-restrained braces (BRBs) is overall flexural buckling caused by connection failure, and they are required to exhibit stable hysteresis under cyclic axial loading with initial out-of-plane drifts simulating the bi-directional effects of a ground motion. In this paper, a series of cyclic loading tests with initial out-of-plane drifts for double web H type BRB and pin-ended tube-in-tube BRB are carried out, and the stability performance including various connection conditions and initial out-of-plane drifts are researched. These results are compared with the stability evaluation equations proposed by the authors, and the validity and accuracy of these equations are discussed.
  • Toru Takeuchi, Ryota Matsui
    JOURNAL OF STRUCTURAL ENGINEERING 141 (7) 0733-9445 2015/07 [Refereed][Not invited]
     
    The postbuckling behavior of seismic-resistant braces in steel frames under a cyclic axial force is often evaluated by time-history analyses; however, brace fracture is seldom considered. The authors previously proposed a physical model for predicting the moment of fracture of circular-tube braces after buckling using phenomenological hysteresis. However, the accuracy of that model was confirmed only against the test results of the gradually increasing amplitude loading protocol, and its applicability under other loading histories has not yet been verified. In this study, cyclic loading tests were carried out until fracture on circular-tube and H-section braces under various loading histories, followed by FEM analyses. The validity of the proposed formulas for evaluating the strain-concentration index under various loading histories was examined. The proposed method was used for predicting the moment of fracture and the cumulative deformation capacity until fracture, and the predictions agreed well with the test results.
  • Out-of-plane response of braces in steel frames with buckling restrained braces subjected to bi-directional earthquake ground motions
    Hitoshi Ozaki, Hidetaka Nagaji, Ryota Matsui, Toru Takeuchi
    J. of Struct. Eng., AIJ (61B) 401 - 408 2015/03 [Refereed][Not invited]
  • Seismic effect of members fracture on truss tower
    Ryota Matsui, Toru Takeuchi, Kentaro Horiuchi, Akira Imamura, Toshiyuki Ogawa
    IABSE Conference, Nara 2015: Elegance in Structures - Report 396 - 397 2015 
    The ultimate strength of truss tower structures is governed by buckling of tubular members which easily leads to the member fracture. This paper proposes the post-fracture analysis methods for truss structures composed with tubular members with high diameter-to-thickness ratios, and a study on the collapse mechanism of such truss towers after buckling and fracture of members is investigated using incremental dynamic analysis (IDA) analysis. Truss towers without stack members exhibited collapse after buckling of main columns or fracture of diagonal members.
  • Ryota Matsui, Shunji Urui, Masaki Tokuno, Toru Takeuchi
    Journal of Structural and Construction Engineering 80 (717) 1745 - 1754 1881-8153 2015 [Refereed][Not invited]
     
    The 2011 Tohoku Earthquake ruptured several asperities at the same time, which generated a large scale and long period ground motion. Recently the higher level of the earthquake ground motion is considered in structural design, and the nonlinearity characteristics such as large plasticity or fracture of members are inevitable issues in seismic performance evaluation of the steel structures. This paper presents the seismic performance of the braced frames is assessed by the time history response analysis program taking fracture of the end of beams and braces into account. The incremental dynamic analysis (IDA) is hired, in order to grasp the ultimate state under extremely large ground motions. The fragility curve was constituted from the analysis results, which provides the member fracture has definitely effect on the seismic performance of the braced frames.
  • Kazuhiko Narita, Yuki Terazawa, Kou Maehara, Yuichi Matsuoka, Ryota Matsui, Toru Takeuchi
    Journal of Structural and Construction Engineering 80 (717) 1717 - 1725 1881-8153 2015 [Refereed][Not invited]
     
    A large numbers of steel roof bearings in RC gymnasia are damaged at past earthquakes at the 2011 Tohoku Earthquake, mainly due to the out-of-plane response of cantilevered RC walls supporting the roof frame. In the conventional seismic retrofit method, bearings reinforcement with steel corner plates and replacement of all the roof braces are required, therefore uneconomical. In this paper, a detailed energy-dissipation bearing with friction dampers for steel roof reducing the response of cantilevered RC walls is fabricated and dynamic loading tests are carried out. Using the experimental results, their response reduction effect is confirmed by analytical models.
  • Toru Takeuchi, Hideji Nakamura, Masakaze Uchida, Michiyasu Yoshida, Ryota Matsui
    Journal of Structural and Construction Engineering 80 (715) 1385 - 1392 1881-8153 2015 [Refereed][Not invited]
     
    Although rubber bearings are popular for seismic isolation bearings in Japan, Spherical Sliding Bearings (SSB) or Friction Pendulum Bearings (FPB) are also widely used in many countries including U. S. In this paper, shaking table tests on braced frame supported by SSB are carried out, and their dependency on pressure and velocity is examined. Also tests with the eccentric dead loads are conduted, in order to capture lift-up actions at bearings and their performance. Analytical models taking pressure and velocity dependency into accounts are proposed, and their validity against the experimental results are discussed.
  • Kazuhiko Narita, Toru Takeuchi, Ryota Matsui
    Journal of Structural and Construction Engineering 80 (708) 273 - 283 1881-8153 2015 [Refereed][Not invited]
     
    In the 2011 Tohoku Earthquake, a large number of school gymnasia suffered damage and were unable to be used as shelters. One of the most typical damage observed in steel roof gymnasia supported by RC frame were failures at the anchored connections of steel roof bearings on RC frames. In the previous paper, we have discussed on the response of cantilevered RC walls supporting steel roofs using analytical model of a damaged gymnasium in the 2011 Tohoku earthquake, and the obtained analytical results were evaluated on the observed damage. In this paper, the action of cantilevered RC walls supporting steel roofs is investigated using parametric analysis model of various school gymnasia. Based on the analytical results, a simple response evaluation method for the cantilevered frames and reaction forces at roof bearings are proposed.
  • Kazuhiko Narita, Yuki Terazawa, Ryota Matsui, Toru Takeuchi
    Journal of Structural and Construction Engineering 80 (707) 157 - 165 1881-8153 2015 [Refereed][Not invited]
     
    Introduction: A largelarge number of steel roof bearings in RC gymnasia are damaged at 2011 Tohoku Earthquake, and out-of-plane response of cantilevered RC walls supporting the roof frame is identified as one of main causes of damage. In order to use these kinds of gymnasia as shelters after the earthquake, they are required seismic retrofit. However, a conventional seismic retrofit method requires strengthening bearings with steel corner plates and replacing all the roof braces, which is uneconomical. In this paper, a seismic retrofit method inserting energy-dissipation elements into the roof bearings is discussed and their response reduction effects on the gymnasium are investigated. 2. Modelling and Response of Non-Retrofitted Model: The analysis model simulates the actual gymnasium damaged in 2011 Tohoku earthquake and the energy-dissipation roof bearings with elasto-plastic or viscous damper are taken into account. The maximum acceleration response of non-retrofitted model at the bearings is about 2.5∼3.0G and the maximum reaction force of bearings is over the yield force of the existing bearings, which corresponds to the actual damage. The maximum acceleration response of non-retrofitted model at the roller bearings is reduced to 1.5G, however, the maximum displacement of the RC cantilevered walls reaches over 300 mm. 3. Response of Retrofitted Model with Energy-Dissipation Bearings: On the basis of the analysis results, a seismic retrofit method using the energy-dissipation bearings shows the significant response reduction effect on the RC cantilevered walls. In the retrofit using the elasto-plastic bearings, the maximum displacement response of the RC cantilevered walls is reduced sufficiently by initial stiffness and limited yield strength bearings. Then, the maximum relative displacement of bearings is suppressed below 50 mm. In the studies of retrofit using the viscous bearings, the maximum displacement and acceleration response of the cantilevered RC walls and the maximum relative displacement of bearings are reduced to a certain extent simultaneously as viscous increases. Then, the maximum reaction force of bearings is kept below the yield force of the existing bearings and the maximum relative displacement of bearings is suppressed below 20 mm. 4. Response Evaluation with equivalent SDOF System and Equivalent Linearization Method: A simplified response evaluation method using the equivalent SDOF system and equivalent linearization method are proposed to analyze the response of the cantilevered RC walls and to determine the optimum performance of the energy-dissipation bearings. The model is composed of the steel roof spring, the cantilevered RC wall mass and spring and the bearings as a non-linear spring. Analysis with equivalent SDOF system can evaluate the maximum reaction force of bearing and the evaluation of their maximum displacement in a safe side. 5. Conclusions: In conclusions, the following results are obtained. 1) A seismic retrofit method inserting energy-dissipation elements into roof bearings shows significant response reduction effect on RC cantilevered walls, keeping boss the reaction force and displacement of bearings non-damaged level. 2) The energy-dissipation bearings with elasto-plastic damper show the significant response reduction effect on the cantilevered RC walls with high stiffness and limited yield strength, while the maximum relative displacement of bearings is suppressed below 50 mm. 3) The energy-dissipation bearings with viscous damper also show the significant response reduction effect on RC cantilevered walls. Both the maximum displacement and acceleration response and the maximum relative displacement of bearings are reduced to non-damaged level, the maximum relative displacement of bearings being suppressed below 20 mm. 4) A simplified response evaluation method using equivalent SDOF system and an equivalent linearization technique are proposed to determine the optimum specification of the energy-dissipation bearings with some margins in the maximum displacement.
  • Fatih Sutcu, Toru Takeuchi, Ryota Matsui
    JOURNAL OF CONSTRUCTIONAL STEEL RESEARCH 101 304 - 313 0143-974X 2014/10 [Refereed][Not invited]
     
    Existing RC buildings conforming to relatively older regulations and codes may lack in seismic resistance. This is especially true for public buildings such as schools or hospitals, which demand efficient retrofitting to ensure safety during and after a seismic event. Although retrofit design with conventional braces (CB) has been practiced for decades, the unbalanced hysteresis behavior of CBs tends to result in damage concentrated in specific stories. Buckling-restrained braces (BRBs), a new generation of bracing system, may increase structural integrity and at the same time reduce seismic response in a building via energy absorption. However, when the maximum story drift exceeds the yield point of RC frame, all structural elements including BRBs lose horizontal stiffness, which may result in both damage at a specific story and residual deformation effects occurring after an earthquake. Therefore, BRBs may be applied to such buildings using elastically designed steel frames (SF). This paper discusses the evaluation of damage distribution and self-centering functions of the elastic steel frames that connect BRBs to RC frames. In addition, we propose a simplified method based on equivalent linearization to design the required amount of BRB and elastic SF capacity for retrofitting existing RC buildings. The results were confirmed by nonlinear time:history analysis using high-intensity seismic waves. The results show that RC buildings retrofit with BRBs respond as predicted by the proposed method and target story drift is obtained. The story drifts of the BRB retrofit model is significantly reduced relative to both the original building and the building retrofit with CBs. In addition, because BRBs are attached to an existing building by elastically designed steel frames, the significant effect of SF on the reduction of residual displacements was also shown and discussed. (C) 2014 Elsevier Ltd. All rights reserved.
  • Toru Takeuchi, Kentaro Horiuchi, Ryota Matsui, Toshiyuki Ogawa, Akira Imamura
    Journal of Structural and Construction Engineering 79 (703) 1309 - 1319 1881-8153 2014/09/01 [Refereed][Not invited]
     
    Although truss towers used for telecommunication, electric power transportation, supporting structures for smokestacks in power plants have been designed against wind loads, a higher level of safety is recently required because of the increase of anticipated large seismic inputs. The ultimate strength of these structures is governed by tubular member buckling which is easily led to member fracture. This paper proposes the post-fracture analysis methods for truss structures composed with tubular members of large diameter-to-thickness ratios, and study on the collapse mechanism of such truss towers after the buckling and fracture of main columns and diagonals are investigated, using IDA analyses taking these member fractures into account.
  • Ryota Matsui, Tsuyoshi Hiroyama, Toru Takeuchi
    Journal of Structural and Construction Engineering 79 (702) 1183 - 1191 1881-8153 2014/08/01 [Refereed][Not invited]
     
    Circular hollow sections (CHS) are widely used as bending members in many structures including moment resisting frames. Several structural design provisions such as CIDECT suggest hot spot method and classification method for assessment of fatigue performance of CHS welded joints particularly in the elastic range. By contrast, the authors have proposed a strain concentration method of H-section beams which requires only displacement at the end of the macro-members to assess the cyclic plastic deformation capacity. This paper presents the experiments on four types of CHS T-joints subjected to cyclic bending moment to investigate the strength and the cumulative plastic deformation capacity. Finite element analysis was used to examine the plastic strain distribution at the strain concentration zone of the CHS T-joints. The strain concentration ratio of the CHS T-joints was established by those testing and numerical results. It was found that the cumulative plastic deformation capacity of the CHS T-joints assessed by the proposed method is by and large consistent with the testing results.
  • Toru Takeuchi, Hitoshi Ozaki, Ryota Matsui, Fatih Sutcu
    EARTHQUAKE ENGINEERING & STRUCTURAL DYNAMICS 43 (6) 851 - 869 0098-8847 2014/05 [Refereed][Not invited]
     
    Buckling-restrained braces (BRBs) are widely used as ductile seismic-resistant and energy-dissipating structural members in seismic regions. Although BRBs are expected to exhibit stable hysteresis under cyclic axial loading, one of the key limit states is global flexural buckling, which can produce an undesirable response. Many prior studies have indicated the possibility of global buckling of a BRB before its core yields owing to connection failure. In this paper, BRB stability concepts are presented, including their bending-moment transfer capacity at restrainer ends for various connection stiffness values with initial out-of-plane drifts, and a unified simple equation set for ensuring BRB stability is proposed. Moreover, a series of cyclic loading tests with initial out-of-plane drifts are conducted, and the results are compared with those of the proposed equations. (c) 2013 The Authors. Earthquake Engineering & Structural Dynamics published by John Wiley & Sons Ltd.
  • Seismic response control of rack warehouse taking slipping and falling of live load into account
    Yuki Matsuno, Toru Takeuchi, Ryota Matsui, Yuji Nishi
    J. of Struct. Eng., AIJ (60B) 569 - 574 2014/03 [Refereed][Not invited]
  • Kazuhiro Fujishita, Ryota Matsui, Torn Takeuchi
    Journal of Structural and Construction Engineering 79 (706) 1961 - 1971 1881-8153 2014 [Refereed][Not invited]
     
    In retrofitting multistory RC buildings which have uniaxial eccentricity, it is important to control torsional displacement to assure safety of' structure under seismic input. In this study, elastic response of each frame of uniaxial eccentric three-dimensional model is evaluated by using a pair of equivalent independent lamped mass models. The easy damper distribution method proposed for plane frames in the previous paper is applied to these pair of lamped mass, and damper distribution in each plane frame are determined. The validity of proposed method is confirmed by applying to three-dimensional model of typical Turkish RC building which has uniaxial eccentricity and weak stories.
  • Toru Takeuchi, Xingchen Chen, Ryota Matsui
    Journal of Structural and Construction Engineering 79 (706) 1941 - 1949 1881-8153 2014 [Refereed][Not invited]
     
    Recently, various controlled rocking systems have been proposed in seismic design to prevent damage concentration and to achieve self-centering against a wide range of input ground motion intensities. However, there are several obstacles to overcome before they can be applied to actual buildings, such as the requirement of large, self-centering post-tensioned (PT) strands and special treatment at uplift column bases. This paper proposes a non-uplifting spine frame system with energy-dissipating members without PT strands its self-centering function relies on envelope elastic moment frames. The system is applied to an actual building constructed in Japan. Conventional shear damper and uplifting rocking systems with PT strands developed in prior studies are applied to the same building structures, and the performance of the three systems, including damage distribution, energy dissipation, self-centering, robustness against severe earthquake, and irregular stiffness, is compared and discussed through numerical simulations.
  • Hitoshi Ozaki, Yoshinao Konishi, Ryota Matsui, Toru Takeuchi
    Journal of Structural and Construction Engineering 79 (706) 1919 - 1929 1881-8153 2014 [Refereed][Not invited]
     
    Buckling restrained braces (BRBs) are widely used in seismic regions as ductile seismic-resistant and energy dissipating structural members. On the other hand, the risk of overall flexural buckling under cyclic axial loading with initial out-of-plane drifts simulating the bi-directional effects of a ground motion has been pointed out. In this regard, series of formula for securing the BRB out-of-plane stability has been proposed in previous studies. However, the actual ranges of each index that make up this series of formula are not clear for practical engineers. In this paper, these index values are clarified by carrying out the research studies of various BRBs and their connections that have been used in actual design. Based on these results, a simple method that can evaluate the out-of-plane stability condition of BRBs with various connection conditions is proposed.
  • Toru Takeuchi, Ryota Matsui, Saki Mihara, Takanori Oya, Yuki Okamoto, Hitoshi Ozaki, Mamoru Iwata
    AIJ Journal of Technology and Design 20 (45) 569 - 574 1881-8188 2014 [Refereed][Not invited]
     
    One of the key limits of buckling-restrained braces (BRBs) is overall flexural buckling caused by connection failure, and they are required to exhibit stable hysteresis under cyclic axial loading with initial out-of-plane drifts simulating the bi-directional effects of a ground motion. In this paper, a series of cyclic loading tests with initial out-of-plane drifts for built-up type BRB is carried out, and the stability performance including various connection conditions and initial out-of-plane drifts are researched. These results are compared with the stability evaluation equations proposed by the authors, the validity and accuracy of these equations discussed.
  • Toru Takeuchi, Yusuke Kinouchi, Ryota Matsui, Toshiyuki Ogawa
    Journal of Structural and Construction Engineering 79 (700) 791 - 799 1881-8153 2014 [Refereed][Not invited]
     
    Application of energy dissipation devices for the seismic retrofit of truss towers has been recently researched, because these structures have been generally designed against wind load, and are possibly to be damaged by large earthquake. Although the effect of energy dissipation devices has been confirmed, the arrangement methodology of these devices has not been established yet. In this study, optimization techniques are applied to arrangements of devices. Firstly, a response evaluation method using response spectrum and equivalent linearization method is proposed. Second, the proposed method is applied to the investigation of optimum arrangement of visco-elastic damper devices on a telecommunication tower. Additionally, the device arrangements by the conventional design methods are compared with the optimum solutions. The results demonstrate that the conventional design is significantly effective to determine the optimum device arrangement.
  • Kazuhiro Fujishita, Fatih Sutcu, Ryota Matsui, Toru Takeuch
    Journal of Structural and Construction Engineering 79 (699) 661 - 669 1881-8153 2014 [Refereed][Not invited]
     
    When retrofitting reinforced concrete buildings in Turkey with energy-dissipation devices, damage distribution between each story become very important, because the ultimate horizontal shear strength in each story is lower than Japanese buildings, and damage concentration at specific story is highly expected. In this paper, a retrofit concept adding elastic frames together with hysteretic dampers is introduced, and the effects of these elastic elements for damage distribution were researched and discussed, also for use in structures including weak stories. The easy damper distribution method using equivalent linearization techniques including the effect of additional elastic frames is proposed, followed by its validity evaluations.
  • Toru Takeuchi, Hitoshi Ozaki, Ryota Matsui
    Journal of Structural and Construction Engineering 78 (691) 1621 - 1630 1340-4202 2013/09 [Refereed][Not invited]
     
    Buckling restrained braces (BRBs) are widely used in seismic regions as ductile seismic-resistant and energy dissipating structural members. One of the key limits of BRBs is overall flexural buckling, and they are required to exhibit stable hysteresis under cyclic axial loading with initial out-of-plane drifts simulating the bi-directional effects of a ground motion. However, many researches are indicating that there are risks of overall buckling caused by connection failure, before the BRB core yields. In this paper, the stability conditions of BRBs including their various connection conditions and initial out-of-plane drift are discussed and a unified simple equation set for securing the BRB stability is proposed. Moreover a series of cyclic loading tests with initial out-of-plane drifts is carried out, and results are compared with the proposed index.
  • Ryota Matsui, Tsuyoshi Hiroyama, Toru Takeuchi
    日本鋼構造協会鋼構造論文集 Japanese Society of Steel Construction 20 (79) 11 - 18 1880-9928 2013/09 [Refereed][Not invited]
     
    When braced moment frames are subjected to a strong ground motion, the bracing elements are likely to fracture. Such fracture results in a large cumulative plastic deformation at the beam end which leads to the connection failure. The authors have proposed a method to assess the brace and beam end fracture using time history response analysis without micro element FEM. However, this method does not take the beam end joint efficiency into account. In this study, the effect of the joint efficiency on the cumulative deformation capacity of the beam end is investigated. Using those results, the seismic performance of the braced moment frame is analyzed including the fracture of brace members and beam ends.
  • Toru Takeuchi, Makoto Nishimaki, Ryota Matsui, Toshiyuki Ogawa
    Journal of Structural and Construction Engineering 78 (690) 1503 - 1512 1340-4202 2013/08 [Refereed][Not invited]
     
    Seismic retrofit of damaged steel school gymnasium with angle braces is often carried out by replacing damaged braces by larger section angle braces with ultimate strength designed connections. However, the effects of the replaced braces for the retrofit against expected seismic input are not confirmed yet. In this paper, a gymnasium damaged by Tohoku Earthquake 2011 was analyzed including the fracture conditions derived from cyclic tests of angle braces. Furthermore, retrofit options using angle braces with ultimate strength designed connections, strength based designed braces, and energy dissipating braces are analyzed using the same model, and their performances are compared including effects on the acceleration response along the roof.
  • Ryota Matsui, Yuka Yamaura, Toru Takeuchi
    Journal of Structural and Construction Engineering 78 (690) 1485 - 1492 1340-4202 2013/08 [Refereed][Not invited]
     
    Lateral-torsional buckling is one of key factors that determine ductile behavior of steel moment frames. Current lateral bracing requirements for beams are established on the basis of monotonic loading conditions in Japanese seismic provisions. However, the relationship between the current provisions and lateral bracing stiffness requirements under cyclic loading conditions has not been confirmed systematically yet. In this study, an experimental study was conducted to assess the effect of lateral bracing stiffness on the H-section beam strength under cyclic loading. Three different lateral bracing types were examined under cyclic antisymmetrical moment. A numerical analysis is used to simulate the experimental results and compute the effects of lateral bracing stiffness, bracing span, stiffener and dead load condition on the H-section beam elasto-plastic lateral-torsional buckling behavior. The results are compared to the requirements of the current provisions and discussed.
  • Kazuhiko Narita, Tom Takeuchi, Ryota Matsui
    Journal of Structural and Construction Engineering 78 (693) 1895 - 1904 1881-8153 2013 [Refereed][Not invited]
     
    At 2011 Tohoku Earthquake, many school gymnasia suffered damages owing to not only Tsunami but the consequent shake. One of the most typical damages observed in steel roof gymnasia supported by RC frame are failures at the anchored connections of Steel roof bearings to RC frames. Such failures were observed in not only aged structure but recently designed gymnasia, which mean that further guideline is strongly required. However, evaluation of reaction forces at these connections is not easy because of complicated response characteristics between steel roofs and cantilevered concrete walls. In this paper, the action of cantilevered RC walls supporting steel roofs is researched using analytical model of actual damaged gymnasium in 2011 earthquake. The obtained analytical results are evaluated on the observed damages, and response characteristics of cantilevered RC walls are discussed, followed by proposal of easy design methods for these connections.
  • Toru Takeuchi, Kentaro Horiuchi, Ryota Matsui, Masashi Watanabe
    Journal of Structural and Construction Engineering 77 (682) 1969 - 1976 1340-4202 2012/12 [Refereed][Not invited]
     
    Recently aluminum braces are used for seismic retrofit of reinforced concrete buildings. Aluminum braces reaches their maximum strength at similar story drift angle as reinforced concrete frames and have a priority to steel tube brace, which buckles where RC frames reaches their maximum strength. However, their cyclic performances after buckling are not confirmed yet. If they cause local buckling after overall buckling, they are expected to be fracture. In this paper, cyclic loading experiments on aluminum braces with pin-end connections are carried out until their fracture, and their performance after buckling is confirmed. Also applying the method for steel tube braces, easy fracture prediction method for aluminum braces is proposed and their validity is discussed.
  • T. Takeuchi, J. F. Hajjar, R. Matsui, K. Nishimoto, I. D. Aiken
    ENGINEERING STRUCTURES 44 (44) 304 - 311 0141-0296 2012/11 [Refereed][Not invited]
     
    Buckling-Restrained Braces (BRBs) are commonly used as ductile bracing elements in seismic zones. Key limit states governing BRB design include preventing both flexural buckling and local buckling failures. In this study, the authors propose a strategy for the prevention of in-plane local buckling failure of a BRB whose restrainer is composed of a mortar in-filled circular or rectangular steel tube with various mortar thicknesses. Cyclic loading tests on BRBs possessing various mortar restrainers and circular tube thicknesses were carried out to investigate the effect of the mortar and the sectional shape of the restraint tube on the local buckling failure of buckling-restrained braces. (C) 2012 Elsevier Ltd. All rights reserved.
  • Toru Takeuchi, Yuki Kondo, Ryota Matsui, Akira Imamura
    Journal of Structural and Construction Engineering 77 (681) 1781 - 1790 1340-4202 2012/11 [Refereed][Not invited]
     
    Seismic-resistant braces subjected to cyclic axial force is known to undergo low-fatigue fracture after local buckling, and theauthors have proposed an easy evaluation method predicting the fracture point of circular and H-section braces after buckling, using macro-member models. However, its validity against such members as built L-section or built C-section is not confirmed yet. In this paper, cyclic loading tests of built-up L, C, and T-section braces under cyclic loading histories are carried out, and FEM analyses following the test results are performed. Reflecting these results, the fatigue failure mechanisms of such braces are discussed including validities of the proposed method.
  • Toru Takeuchi, Makoto Nishimaki, Ryota Matsui, Akira Imamura
    Journal of Structural and Construction Engineering 77 (677) 1131 - 1140 1340-4202 2012/07 [Refereed][Not invited]
     
    The post-buckling behavior of the seismic-resistant braces in braced frames under cyclic axial force is often evaluated by time-history analyses however, they seldom consider brace fracture. Authors have proposed an easy evaluation method predicting the fracture point of the circular and H-section braces after buckling, using macro-models. However, the method is confirmed only against the test results of gradually increased amplitudes and applicability under other loading histories is not verified yet. In this paper, cyclic loading tests on the circular and H-section braces under various loading histories are carried out, and FEM analyses following the test results are performed. Reflecting these results, the validities of the proposed methods for the brace fracture prediction under various loading histories are discussed.
  • R. Matsui, T. Takeuchi
    STESSA 2012: PROCEEDINGS OF THE 7TH INTERNATIONAL CONFERENCE ON BEHAVIOUR OF STEEL STRUCTURES IN SEISMIC AREAS 607 - 613 2012 [Refereed][Not invited]
     
    A Buckling Restrained Brace (BRB) comprises a steel core plate restrained by a mortar-filled steel tube. A key limit state of BRB is determined by the cumulative deformation capacity until the core plate fractures. This capacity decreases to that of the steel material. In this paper, the mechanism that decreases the cumulative deformation capacity of the BRB is explained by local buckling of the core plate, which leads to nonuniform strain distribution of the core plate in the longitudinal direction. The decrease in the cumulative deformation capacity of the BRB can be explained by applying the fatigue performance formula for the steel material to the strain at the local zone. A ratio that compares the strain concentration degree at the local zone with the total normalized deformation is proposed to determine the strain at the local zone relative to the total normalized deformation. In addition, the effect of the exponential value of the fatigue performance formula on the methods for predicting the cumulative deformation capacity of the BRB is investigated.
  • Toru Takeuchi, Yu Nakamura, Ryota Matsui, Toshiyuki Ogawa, Akira Imamura
    Journal of Structural and Construction Engineering 76 (669) 1971 - 1980 1340-4202 2011/11 [Refereed][Not invited]
     
    High-rise truss towers consist of steel tubular section members have high risks to be damaged by seismic input, because their hysteretic characteristics deteriorate after buckling and easy to fracture after local buckling However present design does not include the effect of such member fracture. Authors have established algorism to predict member fracture after buckling for tubular members using macro-model, derived from experimental and analytical studies. In this paper, this algorism is applied for time-history analyses and seismic responses of detailed tower structures are analyzed. The validity of proposed method is firstly compared with actual earthquake damages, followed by researches on the effect of member fracture in various truss towers.
  • Toru Takeuchi, Ryota Matsui
    JOURNAL OF STRUCTURAL ENGINEERING-ASCE 137 (11) 1311 - 1318 0733-9445 2011/11 [Refereed][Not invited]
     
    Tubular-section members are commonly used as seismic-resistant braces because they have a higher moment of inertia than open cross sections of equivalent area. However, the cumulative cyclic deformation capacity of tubular sections after buckling is smaller than that of open sections, such as H-shaped sections, because fracture is initiated by local buckling of circular tubular sections. To evaluate the seismic performance of such diagonal braces, it is essential to predict the cumulative cyclic deformation capacity of these braces before any fracturing. In this study, the cumulative cyclic deformation capacity of circular tube braces under local buckling was assessed by performing cyclic loading tests for a range of slenderness and diameter-to-thickness ratios. The mechanism of strain concentration in the tubular braces was studied in various types of analysis, and a method is proposed for assessing the cumulative deformation capacity before fracture based on the entire axial deformation of the braces. DOI: 10.1061/(ASCE)ST.1943-541X.0000380. (C) 2011 American Society of Civil Engineers.
  • Toru Takeuchi, Yosuke Yamamoto, Mitsumasa Midorikawa, Kazuhiko Kasai, Jerome F. Hajjar, Tsuyoshi Hikino, Ryota Matsui, Shoichi Kishiki
    Journal of Structural and Construction Engineering 76 (667) 1695 - 1704 1340-4202 2011/09 [Refereed][Not invited]
     
    The authors have conducted a series of experimental studies on the response characteristics of controlled rocking systems. This system comprises components that include a rocking frame, post-tensioning anchorages, and energy dissipation fuses, eliminating the residual deformation after the earthquake. In this paper, the shaking table test of the controlled rocking system using a Buckling Restrained Brace as the energy dissipation fuse is discussed, including analytical simulations. A procedure to estimate maximum response is introduced based on the concept using maximum instantaneous input energy. The characteristics of the input energy and the accuracy of the proposed approach are demonstrated by comparing the prediction with numerical results as well as experimental results.
  • Ryota Matsui, Toni Take Uchi
    Journal of Structural and Construction Engineering 76 (665) 1337 - 1345 1340-4202 2011/07 [Refereed][Not invited]
     
    A moment frame with bracing elements is one of efficient seismic-resistant stmctural system in elastic design, howevei when the seismic input is larger than the buckling strength of braces, these undergo local buckling subsequent to overall buckling, and the concentration of plastic strain at local buckling area easily leads to brace fracture. The authors have previously proposed a brace fracture prediction method. In this paper, time-history response analyses for braced frames are cathed out focusing on the brace fracture using the proposed method. A discussion follows fatigue distribution in the frame types, including the effect of the brace fracture itself.
  • Toru Takeuchi, Yuki Kondo, Kohji Nishimoto, Ryota Matsui
    Journal of Structural and Construction Engineering 76 (663) 989 - 996 1340-4202 2011/05 [Refereed][Not invited]
     
    A Buckling Restrained Brace (BRB) with serially connected tubular members is one of the solutions for composing BRB over 10m length economically for the seismic design of truss structures or large-span structures. Their overall buckling condition is considered to be sensitive for imperfections or eccentricities comparing to ordinary BRBs however, their effects are not confirmed by experiments yet. In this paper, the overall buckling conditions for BRBs with serially connected tubular members are discussed as the functions of imperfections or eccentricities. Their effects on the stability are confirmed by cyclic loading experiments until member fractures, and design criteria are proposed.
  • Toru Takeuchi, Tatsuya Ohyama, Ryota Matsui
    Journal of Structural and Construction Engineering 76 (661) 695 - 702 1340-4202 2011/03 [Refereed][Not invited]
     
    Structural system composed of high-strength steel frame with energy-dissipation elements is one of the suitable solutions for damage tolerant structure. In this concept, the main structure is designed in elastic zone for design earthquake level however, there are still some risks to step into plastic zone in maximum considered earthquake levels. Because of high strength steel having high yield ratio, it is concerned to fracture early after yielding. In this paper, following the mock-up cyclic-loading tests and analysis of 800Mpa steel beam-column frame with diagonal BRBs, their fracture mechanism of beam-end connections are modeled using simple non-linear rotation springs, and estimation method for their cumulative energy dissipation capacities until their fractures in multistory structures are proposed.
  • Post-buckling hysteresis and cumulative deformation capacity of H-section braces considering their connection rigidity
    Toru Takeuchi, Yu Nakamura, Ryota Matsui
    J. Struct. Constr. Eng., AIJ 75 (653) 1289 - 1297 2010/08 [Refereed][Not invited]
  • T. Takeuchi, J. F. Hajjar, R. Matsui, K. Nishimoto, I. D. Aiken
    JOURNAL OF CONSTRUCTIONAL STEEL RESEARCH 66 (2) 139 - 149 0143-974X 2010/02 [Refereed][Not invited]
     
    Buckling Restrained Braces (BRBs) are commonly used as bracing elements in seismic zones. A key limit state governing BRB design is to prevent flexural buckling. However. when the wall thickness of the steel tube restrainer is relatively small compared to the cross-section of the core plate. the restraint conditions against the local buckling of the core plate can be critical for the stability and strength of the BRB. In this study, cyclic loading tests and numerical analyses of BRBs were carried out using various tube restrainer configurations to investigate the influence of local buckling of the restrainer on BRB strength and ductility. (C) 2009 Elsevier Ltd. All rights reserved.
  • Toru Takeuchi, Ryota Matsui, Kohji Nishimoto, Satoshi TakaHashi, Tatsuya Ohyama
    Journal of Structural and Construction Engineering 74 (639) 925 - 934 1340-4202 2009/05 [Refereed][Not invited]
     
    Buckling Restrained Braces (BRBs) are commonly used as doctile bracing elements in seismic design. A key limit of BRB is overall flexumi buckling. Howevei their effective buckling lengths are affected by the stifihess and strength of their connection zones. In this paper, each connection zone is modeled as two rotational elastic springs at gusset plate and two rotational elasto-plastic springs at the end zone of the restrainer. Their stiffness and strength are investigated by mock-up experiments and analyses, and their evaluation methods are proposed.
  • Torn Takeuchi, Kang Qin and Ryota Matsui
    Journal of Structural and Construction Engineering 73 (632) 1875 - 1882 1340-4202 2008/10 [Refereed][Not invited]
     
    H-section braces are widely used for seismic-proof elements in various kinds of structures. However, when they receive the cyclic loading beyond the expected seismic loads, they cause not only overall-buckling, but local buckling. It is known that such local buckling cause stress concentration within limited zones, and easily lead to the fracture of the member itself. Various hysteretic loop models for such braces have been proposed and used for timehistory analysis, however, it is not easy to predict the point of the fracture, their cumulative deformation capacity and energy dissipation capacity until the fracture. In this paper, cyclic loading tests on various H-section braces are carried out, and their fracture mechanism, relationship between the slenderness ratios and width-thickness ratios are researched. Their strain concentration mechanism is discussed through various analyses, followed by proposing easy evaluation method of their cumulative deformation capacity.
  • Toru Takeuchi, Kazuaki Suzuki, Ryota Matsui, Toshiyuki Ogawa
    J. Struct. Constr. Eng., AIJ 日本建築学会 72 (620) 141 - 148 1340-4202 2007/10 [Refereed][Not invited]
     
    Tubular sections are commonly used for truss structures or diagonal braces, because they have higher moment-of-inertia comparing to H-sections or L-sections with the same area. However, their cumulative cyclic deformation capacity after buckling is known as quite small, because high strain concentration appears at local elbow buckling. To improve the performance of such members, the authors have proposed retrofit method to add outer tube and in-filled mortar in-between, as buckling restrainer. In this paper, cumulative cyclic deformation capacity of this member is researched by cyclic loading tests with various thickness ratios and strain amplitudes. Their strain concentration mechanism is also researched thorough various analyses, followed by proposing the concept of strain concentration index. The easy evaluation method for cumulative deformation capacity and energy dissipation capacity is proposed using this index.
  • An experimental study on cumulative cyclic deformation capacity of tubular braces with local buckling
    Kazuaki Suzuki, Toru Takeuchi, Ryota Matsui, Toshiyuki Ogawa
    Proceedings of 8th Pacific Structural Steel Conference - Steel Structures in Natural Hazards, PSSC 2007 1 57 - 62 2007 
    Tubular sections are commonly used for truss structures or diagonal braces, because they have higher moment-of-inertia comparing to open cross-sections with the same area. However, their cumulative cyclic deformation capacities after buckling are known as quite small comparing to H-sections, because strain concentration occurs with local elbow buckling. For evaluating seismic performances of such structures, cumulative cyclic deformation capacity of braces before fracture is essential. In this paper, cumulative cyclic deformation capacity of tubular braces with local buckling is researched by cyclic loading tests with various slenderness ratios and thickness ratios. Their strain concentration mechanism is researched thorough various analyses.
  • Toru Takeuchi, Kazuaki Suzuki, Ryota Matsui, Toshiyuki Ogawa
    J. Struct. Constr. Eng., AIJ 日本建築学会 71 (608) 143 - 150 1340-4202 2006/10 [Refereed][Not invited]
     
    Tubular sections are commonly used for truss structures or diagonal braces, because they have higher moment-of-inertia comparing to open cross-sections with the same area. However, their cumulative cyclic deformation capacities after buckling are known as quite small comparing to H-sections, because strain concentration occurs with local elbow buckling. For evaluating seismic performances of such structures, cumulative cyclic deformation capacity of braces before fracture is essential. In this paper, cumulative cyclic deformation capacity of tubular braces with local buckling is researched by cyclic loading tests with various slenderness ratios and thickness ratios. Their strain concentration mechanism is researched thorough various analyses, followed by proposing easy evaluation method of cumulative deformation capacity.

MISC

Association Memberships

  • Japan Society of Steel Construction   Architectural Institute of Japan   

Research Projects

  • 日本学術振興会：科学研究費助成事業
    Date (from‐to) : 2023/06 -2026/03 
    Author : 松井 良太, 岡崎 太一郎, 丸山 一平
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)
    Date (from‐to) : 2020/04 -2024/03 
    Author : 岡崎 太一郎, 松井 良太, 岸田 明子, 松宮 智央, 高橋 典之, 藤原 淳, 長江 拓也
     
    鋼構造建築物の倒壊過程を実験的に解明する研究目的に沿って、国立研究開発法人防災科学技術研究所の大型耐震実験施設で、2020年11月から12月にかけて、縮尺1/2のパイロット試験体による振動台実験を実施した。防災科学技術研究所の兵庫耐震工学研究センターで、2020年12月に実施された日米共同実験に参加し、次世代型鋼構造システムを開発する研究を推進した。また、倒壊に至る鋼構造の非線形・動的挙動を追跡するコンピュータ解析技術を確立する研究目的に沿って、数値モデル化技術を種々検討した。一連の研究活動で得られた成果は、下記のとおりである。（１）模型実験の設計方法、柱や梁の降伏・破断挙動を測定するための計測・画像収録方法を確立し、2021年度に実施する本実験の準備を固めた。（２）複数の実験から得た、鋼構造架構の非線形動的応答に関する実データを、既往の大規模振動台実験のデータと合わせて、数値解析技術の検証を進めた。特に、破断を模擬するための現状のモデル化手法では、既往の重層架構実験で観察された、部材破断後の部材力再分配を正しく再現できないことを突き止め、今後の課題を特定した。減衰モデルの選択によって、ブレース付架構の応答変位や応答加速度が異なることに注目し、定量的な検討を進めた。（３）部材破断の再現方法を含めて、ブレース付鋼構造架構の解析手法に関する知見を蓄積し、現状のブレース付鋼構造架構が保有する耐震性能を検証した。
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Date (from‐to) : 2020/04 -2023/03 
    Author : 松井 良太, 岡崎 太一郎, 竹内 徹
     
    災害時における鋼構造物の被災事例は枚挙にいとまがなく，地震や風により崩壊した事例は年々増え続けている。人命を保護するため，局部座屈や部材破断などの不安定現象により，鋼構造物が倒壊しないよう設計手法が体系化されているが，事業継続性や居住快適性が重視されるなど，鋼構造物に対する要求は高度化しつつある。現行の設計体系で規定されていない鋼構造物の性能を迅速に評価できる信頼性の高い手法を，構造設計に携わる実務者が利用できれば，より冗長性の高い社会基盤を構築し得ると考えられる。本研究課題では，設計者の技量や熟練度に依らず，鋼構造物の限界性能を検証できる構造設計手法を提示することを目標としている。 数値解析プログラム整備のため，数値解析によりブレースおよび梁の耐力や塑性変形性能を検証した。梁については，これまで純鉄骨を中心として数値解析モデルを検討し，実構造物で多用される合成梁も含め検討する必要性を実感し，本研究課題に追加した。床スラブの仕様を変えた3種の合成梁に関して載荷実験を実施した。 ブレースの性能を整理したデータベースを構築するため，国内外における90件程度の既往の研究成果を調査し，502体の繰返し荷重を受けるブレース試験体の実績を抽出した。うち多数を占めたH形56体，中空円形62体，中空角形90体の断面を有する試験体のうち，建築基準法上，高い塑性変形能力があるランクに分類された試験体は1割から2割程度と寡少であることを確認した。同ブレースは実務上用いられる頻度は高く，構造性能を検証することが急務であることを再認識した。 構築したデータベースを参照し模型載荷実験では実績の少ない試験体として，断面や端部境界条件が異なる，有効細長比10から20の太短い試験体6体と，有効細長比30と80の試験体2体を製作した。載荷実験に向け実験場を整備し，効率的に模型載荷実験を進められるよう準備した。
  • Elastic-Plastic Behavior of Panel Zone in Concrete-Filled Composite Structures with Autogeneous Shrinkage of Concrete Material
    The Japan Iron and Steel Fabrication：鋼構造研究・教育助成事業
    Date (from‐to) : 2021/04 -2023/03
  • Numerical Model of Steel Braces for Collapse Analysis Based on A Quantitative Evaluation for Ductility Capacity
    鹿島学術振興財団：研究助成
    Date (from‐to) : 2020/04 -2022/03
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Date (from‐to) : 2018/04 -2021/03 
    Author : Takeuchi Toru
     
    In 2016 Kumamoto earthquake, roof members of system truss gymnasiums buckled and ruptured, and some of them fell. The system truss is a structural system widely used in gymnasiums in Japan, however, they are designed to be elastic against the design load, and the bearing capacity margin and collapse behavior against large seismic input have not been clarified. In this study, the collapse mechanism of the system truss roof structure supported by RC frames has been clarified through member tests, truss unit tests, partial frame shaking table tests and analysis. In addition, a construction method to prevent the collapse of the entire roof, the introduction of energy absorbing elements into the bearing to reduce the response, and their design method were proposed, followed by researches on immediate risk assessment based on the measurement of point cloud data after the earthquake.
  • Estimation of Cumulative Deformation Capacity for Beam End of I-Shaped Sections with One-Dimensional Finite Element Analysis
    The Japan Iron and Steel Fabrication：鋼構造研究・教育助成事業
    Date (from‐to) : 2019/04 -2021/03
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (A)
    Date (from‐to) : 2017/04 -2020/03 
    Author : Matsui Ryota
     
    A facility for thermal power generation is one of the most important urban infrastructures. Steel structures are typically used for the facility. This kind of facilities necessary to support heavy masses such as a boiler, which in turn lead to high axial load of steel columns. This study presents the strength and ductility of the steel columns subjected to high axial load based on physical tests of members. A phenomenological fiber element was proposed to reproduce the local buckling-induced softening of those steel columns reasonably. The number of elements of the phenomenological fiber element was relatively less than that of the finite element analysis with shell elements. A numerical program for time history response analysis was developed using the phenomenological fiber element to assess the seismic performance of the facilities with heavy masses. The program was validated by a past shake table test of a 4-story steel moment frame including local buckling-induced softening.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Date (from‐to) : 2015/04 -2018/03 
    Author : Takeuchi Toru
     
    Numerous steel roof bearings in RC gymnasiums were damaged at the 2011 Tohoku Earthquake. These damages are considered to be mainly due to out-of-plane response of cantilevered RC walls; however, their mechanisms are not clear. In this research, complicated response characteristics of these roof and RC walls are made clear. The real scale mock-up experiments of PTFE sliding bearings, friction damper bearings, and rubber sheet bearings are carried out, followed by the shaking table test for seismically isolated roofs. From these results, detailed construction methods for eliminating the damages without strengthening the roof, followed by proposing the evaluation methods. Also the steel roofs supported by seismic isolation bearings are investigated, followed by shaking table tests and response evaluations.
  • Shake Table Testing of Steel Braced Frame Considering Member Fracture
    The Japan Iron and Steel Fabrication：鋼構造研究・教育助成事業
    Date (from‐to) : 2015/04 -2016/03
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)
    Date (from‐to) : 2012/04 -2015/03 
    Author : MATSUI Ryota
     
    In this research, the cumulative deformation capacity of the end of the beam was investigated on the basis of the experimental and numerical data, and an evaluation method for assessing the ultimate state of the high-rise buildings under long period ground motion was proposed. Additionally the lateral bracing requirements for H-section beams under cyclic loading was examined by experiments and numerical analysis. To expand the proposed evaluation method, the cumulative deformation capacity of the circular hollow section T-joints was investigated by experiments and finite element analysis. The seismic performance of buildings under severe ground motion in a range of the dominant natural period of the buildings was examined, using the time history analysis program including fracture of the braces and connections. This analysis results also provide a fragility curve of the buildings including the connection fracture effect.
  • 日本学術振興会：科学研究費助成事業 特別研究員奨励費
    Date (from‐to) : 2008 -2010 
    Author : 松井 良太
     
    最終年度となる平成22年度においては,昨年度において構成した三次元構造物を対象とした時刻歴応答解析手法を用いて,ブレース部材の破断を考慮した大地震時におけるブレース付ラーメン骨組のエネルギー吸収性能について分析した。その結果,ブレース部材の破断を考慮した場合のブレース付ラーメン骨組の時刻歴応答およびエネルギー吸収性能は,考慮していない場合に比較して大きな差異を生じることを示した。プレースの部材破断を考慮した場合,骨組の変位応答に大きな差異は見られないものの,柱梁の負担するエネルギー吸収量が大きく増大する例も見られた。本研究では,柱梁のエネルギー吸収性能については対象外としていたが,ブレースの部材破断に伴い柱梁の損傷が増大し,骨組全体のエネルギー吸収性能が大きく低下する可能性があることが確認された。 以上より,既存不適格建物の耐震補強に用いる鋼材ブレースが地震力を受けて破断に至るまでのエネルギー吸収性能を評価し,同ブレースを用いた骨組の大地震時における時刻歴応答およびエネルギー吸収性能を比較検証することが可能となった。これにより,既存不適格建物に想定以上の地震動が入力された場合に必要となる鋼材ブレースの補強量を,より適切に把握できるようになると考えられ,信頼性の高い耐震補強設計法の確立に貢献したものと考えられる。 以上の研究成果は国内外の学術会議および学術雑誌を通して発表しており,多数の研究者との意見交換および交流を密に図ることが出来た。

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