Researcher Profile and Settings

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)

  OKAZAKI

• Name (Kana)

  Taichiro

• Name

  201201072825406950

Alternate Names

http://hokudai-str-eng.jpn.org/
http://hokudai-str-eng.jpn.org/en/

Achievement

Research Interests

• Steel structures   Seismic performance and design   Steel connections   Seismic isolation   

Research Areas

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

Research Experience

• 2016/04 - Today Hokkaido University Faculty of Engineering Professor
• 2011/04 - 2023/03 独立行政法人防災科学技術研究所 兵庫耐震工学研究センター 客員研究員
• 2017/04 - 2020/03 Dalian University of Technology Visiting Professor
• 2011/01 - 2016/03 Hokkaido University Faculty of Engineering Associate Professor

Committee Memberships

• 2023/06 - Today   Architectural Institute of Japan   Board Member (Academics)
• 2012/04 - Today   Architectural Institute of Japan   Subcommittee on Environmental Issues of Steel Structures; Former Chair (2019.4～2023.5)
• 2021/02 -2024/01   Journal of Earthquake Engineering   Associate Editor
• 2020/06 -2022/05   Architectural Institute of Japan   Chairaman on Academics, Hokkaido Branch
• 2017/06 -2019/05   Architectural Institute of Japan   Board Member (Academics)

Published Papers

• An experimental study on the shear, tensile and peel strength of adhesively bonded steel-to-steel joints

  Haruna Takano, Yosuke Watanabe, Taichiro Okazaki

  Steel Construction Engineering, Japan Society of Steel Construction 31 (123) 37 - 47 2024/10 [Refereed]
  
• Bidirectional Cyclic Loading Performance of a Prefabricated Self-Centering Metallic-Damped Steel Column Base

  Junxian Zhao, Hao Qin, Taichiro Okazaki, Yan-Wen Li, Chaohai Guo

  Journal of Structural Engineering 150 (10) 0733-9445 2024/10 [Refereed]
  
• Effect of composite slab and connection detail on cyclic behavior of steel beam-to-HSS column moment connections

  Jialiang Jin, Tianhao Yan, Takuya Nagae, Taichiro Okazaki, Tomohiro Matsumiya, Noriyuki Takahashi

  Journal of Building Engineering 95 110254 - 110254 2352-7102 2024/10 [Refereed]
  
• A comprehensive review of shear connectors in demountable composite beams

  Xin Li, Jing He, Yuxin Zhou, Fei Xu, Taichiro Okazaki, Han Fang

  Journal of Constructional Steel Research 218 108723 - 108723 0143-974X 2024/07 [Refereed][Not invited]
  
• Seismic resilient steel moment connections with top shear tabs and bottom replaceable metallic fuse: Analytical and experimental study

  Junxian Zhao, Hao Qin, Taichiro Okazaki, Fangxin Hu, Zexin Cai

  Engineering Structures 306 117789 - 117789 0141-0296 2024/05 [Refereed]
  
• Seismic performance of self-centring connections with two energy dissipation stages for reusable modular steel buildings

  Jing He, Xuhong Zhou, Fei Xu, Yu Shi, Taichiro Okazaki

  Thin-Walled Structures 196 111442 - 111442 0263-8231 2024/03 [Refereed]
  
• Modeling uncertainty of specimens employing spines and force‐limiting connections tested at E‐defense shake table

  Bryam Astudillo, David Rivera, Jessica Duke, Barbara Simpson, Larry A. Fahnestock, Richard Sause, James Ricles, Masahiro Kurata, Taichiro Okazaki, Yohsuke Kawamata, Zhuoqi Tao, Yi Qie

  Earthquake Engineering & Structural Dynamics 52 4638 - 4659 0098-8847 2023/07/26 [Refereed]
  
• Numerical simulation of the cyclic‐loading behavior of steel chevron‐braced moment‐resisting frames

  Ilanildo Dias, Akiri Seki, Taichiro Okazaki

  JAPAN ARCHITECTURAL REVIEW 6 (1) 2475-8876 2023/01 [Refereed]
  
• Japanese Efforts to Promote Steel Reuse in Building Construction

  Masanori Fujita, Tetsuya Fujita, Mamoru Iwata, Yoshihiro Iwata, Tomomi Kanemitsu, Urara Kimura, Kazuhiko Koiwa, Mitsumasa Midorikawa, Taichiro Okazaki, Satoshi Takahashi, Teruhisa Tanaka, Masatoshi Wada

  Journal of Structural Engineering 149 (1) 04022225-1 - 04022225-13 0733-9445 2023/01 [Refereed]
  
• IN-SITU TESTS TO EVALUATE THE STRUCTURAL PERFORMANCE OF A LARGE, IMPORTED STEEL-FRAMED GREENHOUSE

  Yuta FUKE, Taichiro OKAZAKI, Ryota MATSUI

  AIJ Journal of Technology and Design 28 (70) 1236 - 1241 1341-9463 2022/10/20 [Refereed]
  
• Mechanism and Experimental Validation of Frictional Steel Truss Coupling Beams

  Yao Cui, Qi Tang, Tianjiao Wu, Taichiro Okazaki, Tao Wang

  Journal of Structural Engineering 148 (9) 0733-9445 2022/09 [Refereed][Not invited]
  
• SEISMIC PERFORMANCE OF A LARGE STEEL UNIT HOUSE FURBISHED WITH EXTERNAL WALL PANELS

  Ryosuke MATSUDA, Taichiro OKAZAKI, Takuya NAGAE, Tomohiro MATSUMIYA, Noriyuki TAKAHASHI, Yoshikazu KANZAKI, Takahiro FUKUI, Toshihiko IIJIMA, Yoshiro KIRIYAMA, Koichi KAJIWARA

  AIJ Journal of Technology and Design 28 (69) 679 - 684 1341-9463 2022/06/20 [Refereed][Not invited]
  
• Cyclic-Loading Performance of Steel Beam-to-Column Moment Connections to an I-Section Column

  Martin Somarriba, Taichiro Okazaki, Junxian Zhao, Kensuke Komatsu

  Journal of Structural Engineering 148 (4) 0733-9445 2022/04 [Refereed]
  
• SHAKE TABLE TESTS TO EXAMINE THE SEISMIC PERFORMANCE OF STEEL UNIT HOUSES

  Ryosuke MATSUDA, Taichiro OKAZAKI, Takuya NAGAE, Tomohiro MATSUMIYA, Yoshikazu KANZAKI, Takahiro FUKUI, Toshihiko IIJIMA, Yoshiro KIRIYAMA, Koichi KAJIWARA

  AIJ Journal of Technology and Design 28 (68) 209 - 214 1341-9463 2022/02/20 [Refereed][Not invited]
  
• Seismic performance of steel chevron braced frames designed according to Japanese practice

  Akiri Seki, Keisuke Inoue, Taichiro Okazaki, Shogo Hashioka, Hayato Asada

  Journal of Constructional Steel Research 189 107066 - 107066 0143-974X 2022/02 [Refereed]
  
• Pixel‐level multicategory detection of visible seismic damage of reinforced concrete components

  Zenghui Miao, Xiaodong Ji, Taichiro Okazaki, Noriyuki Takahashi

  Computer-Aided Civil and Infrastructure Engineering 1 - 18 1093-9687 2021/02/15 [Refereed][Not invited]
  
• INFLUENCE OF VISCOUS DAMPING MODEL ON TIME-HISTORY RESPONSE ANALYSIS OF ELASTIC-PLASTIC SYSTEMS (PART 1): COMPARISON OF DAMPING MODELS

  Sho FUKUTOMI, Taichiro OKAZAKI, Ryota MATSUI, Tetsuhiro ASARI

  Journal of Structural and Construction Engineering (Transactions of AIJ) 85 (778) 1555 - 1563 1340-4202 2020/12 [Refereed][Not invited]
  
• Full-Scale Testing and Design of Special Truss Moment Frames for High-Seismic Areas

  Shih-Ho Chao, Chatchai Jiansinlapadamrong, Sanputt Simasathien, Taichiro Okazaki

  Journal of Structural Engineering 146 (3) 04019229 - 04019229 0733-9445 2020/03 [Refereed][Not invited]
  
• Numerical Analysis Focusing on Stiffness Deterioration Behavior of Composite Beam Subjected to Cyclic Deformations.

  Yusuke Nonoyama, Takuya Nagae, Taichiro Okazaki, Tomohiro Matsumiya, Noriyuki Takahashi, Koichi Kajiwara, Hiroshi Nakazawa, Tadashi Mikoshiba

  AIJ Journal of Technology and Design 26 (62) 153 - 158 2020/02 [Refereed][Not invited]
  
• Response of hybrid isolation system during a shake table experiment of a full scale isolated building

  Camila B. Coria, Keri L. Ryan, Eiji Sato, Tomohiro Sasaki, Taichiro Okazaki

  Earthquake Engineering and Structural Dynamics 47 (12) 2214 - 2232 0098-8847 2018/09 [Refereed][Not invited]
   

  A full-scale 5-story steel moment frame building was subjected to a series of earthquake excitations using the E-Defense shake table in August, 2011. For one of the test configurations, the building was seismically isolated by a hybrid system of lead-rubber bearings and low friction roller bearings known as cross-linear bearings, and was designed for a very rare 100 000-year return period earthquake at a Central and Eastern US soil site. The building was subject to 15 trials including sinusoidal input, recorded motions and simulated earthquakes, 2D and 3D input, and a range of intensities including some beyond the design basis level. The experimental program was one of the first system-level full-scale validations of seismic isolation and the first known full-scale experiment of a hybrid isolation system incorporating lead-rubber and low friction bearings. Stable response of the hybrid isolation system was demonstrated at displacement demands up to 550 mm and shear strain in excess of 200%. Torsional amplifications were within the new factor stipulated by the code provisions. Axial force was observed to transfer from the lead-rubber bearings to the cross-linear bearings at large displacements, and the force transfer at large displacements exceeded that predicted by basic calculations. The force transfer occurred primarily because of the flexural rigidity of the base diaphragm and the larger vertical stiffness of the cross-linear bearings relative to the lead-rubber bearings.
• Effect of out-of-plane stiffness and strength on buckling strength of hss brace with single-shear bolted joints

  Hayato Asada, Taichiro Okazaki, Tsuyoshi Tanaka, Saya Nakai, Shogo Hashioka

  Journal of Structural and Construction Engineering 83 (744) 309 - 319 1340-4202 2018/02 [Refereed][Not invited]
   

  © 2018 Architectural Institute of Japan. All rights reserved. A typical bracing connection for hollow-structural-section (HSS) braces comprises a flat plate welded to the brace, a gusset plate, and a single-shear bolted joint between the flat plate and gusset plate. Where such bracing connection is adopted, the rotational stiffness and strength of the bracing connection must be taken into account to evaluate the brace strength in compression. This paper proposes analysis models for this problem, derives buckling strength formulae, and verifies the formulae with monotonie loading tests. Validated finite element models are used to conduct an extensive parametric study to verify the formulae over a wide range of geometrical properties. The proposed formulae predicted the buckling modes for 110 of 118 cases and estimated the brace strength within a coefficient of variation of 3.7% and error margin of 10% for the range of properties examined.
• Panelized Residential Roof System. I: Structural Design

  Susan C. Mantell, Giovanni L. Di Muoio, Jane H. Davidson, Carol K. Shield, Brian J. Siljenberg, Taichiro Okazaki

  Journal of Architectural Engineering 23 (4) 04017020-1 - 04017020-16 1076-0431 2017/12/01 [Refereed][Not invited]
   

  Two roof panel designs for residential applications were developed to span from ridge to soffit without intermediate supports. The two designs, the truss core and the stiffened plate, incorporate both structural and insulation features such that a conditioned attic space can be achieved. The structural component of the truss-core and stiffened-plate panels is fabricated from steel webs laser welded to steel face sheets. The truss core includes an exterior (roof side) and interior (attic side) face sheet, whereas the stiffened plate includes only an interior face sheet. A separate polyurethane foam insulating layer is located on either the panel interior or exterior face. Structural performance requirements are developed from residential building codes for web failure, flexural capacity, and deflection. The structural analysis includes dead, live, and wind loads for all three U.S. climate zones. A model for panel performance was developed and validated through prototype panel tests. Truss-core and stiffened-plate panel designs were identified that satisfy the loading requirements for horizontal spans ranging from 3 to 8 m. Stiffened-plate panels are generally lighter weight than truss-core panels by 10-25%. However, only the truss-core panel satisfies the most extreme loading case for 8-m roof spans.
• Seismic behavior and fragility curves of replaceable steel coupling beams with slabs

  Xiaodong Ji, Yandong Wang, Junshan Zhang, Taichiro Okazaki

  ENGINEERING STRUCTURES 150 622 - 635 0141-0296 2017/11 [Refereed][Not invited]
   

  Replaceable steel coupling beams (RSCB) have been proposed as an alternative to conventional reinforced concrete (RC) coupling beams for enhanced seismic resiliency of coupled wall systems. This paper presents a series of quasi-static tests conducted to examine the seismic behavior of RSCBs with RC slabs and to identify reasonable slab configurations that can minimize the damage to RC slabs. A total of five large-scale specimens were designed and tested. The first four specimens adopted the same end plate link-to-beam connection but adopted different types of RC slabs, including a composite slab, bearing slab, isolated slab or slotted slab. The fifth specimen adopted splice plate link-to-beam connection and a bearing slab. The test results indicate that all specimens developed a large inelastic rotation capacity of more than 0.05 rad with stable hysteretic response. The presence of RC slabs is found to have limited effect on the shear strength and inelastic rotation capacity of RSCBs. Some types of RC slabs increased the initial elastic stiffness of RSCBs, but in the plastic stage, none of the slabs affected the loading or unloading stiffness. Among those four types, of slabs, the composite slab suffered the most significant damage, as a result of pulling out of shear studs and subsequent pouching failure of the slab. Compared with the bearing slab or slotted slab, the isolated slab developed much fewer and smaller cracks, which should allow for easier repair. Based on the observations of this test and previous tests, four damage states for RSCBs were identified, corresponding to different repair methods. Fragility curves of RSCBs at various damage states were developed, which can provide the criteria for seismic performance assessment of RSCBs. (C) 2017 Elsevier Ltd. All rights reserved.
• Bolted Built-Up Columns Constructed of High-Strength Steel under Combined Flexure and Compression

  Xuchuan Lin, Taichiro Okazaki, Kazuhiro Hayashi, Masayoshi Nakashima

  JOURNAL OF STRUCTURAL ENGINEERING 143 (2) 04016159  0733-9445 2017/02 [Refereed][Not invited]
   

  New high-strength structural steel, named H-SA700, is utilized to achieve a structural system that enables continuous use after very large earthquakes. Columns are built up of H-SA700 plates using bolts only, and bolted connections are adopted extensively for easier replacement or reuse of structural components. An analytical study is performed to predict three distinctive local buckling modes of the column and estimate its elastic flexural stiffness, yield strength, and maximum strength subjected to combined flexure and compression. Cyclic loading behavior of the column is examined through five half-scale specimens, which vary with axial force, bolt pitch, and loading direction (about major or minor axis). The columns achieve a very large elastic rotation, approximately 0.02 rad at the axial force ratio of 0.2, and a maximum bending strength surpassing the plastic moment of the reduced section accounting for bolt holes without fracture. The proposed equations predict the local buckling modes well and present a reasonably conservative estimation on the column strength subjected to combined flexure and compression. (C) 2016 American Society of Civil Engineers.
• Cyclic Behavior of Replaceable Steel Coupling Beams

  Xiaodong Ji, Yandong Wang, Qifeng Ma, Taichiro Okazaki

  JOURNAL OF STRUCTURAL ENGINEERING 143 (2) 04016169  0733-9445 2017/02 [Refereed][Not invited]
   

  For improving the seismic resiliency of coupled shear wall systems, a type of replaceable steel coupling beam was developed, which consists of a central fuse shear link connecting to steel beam segments at its two ends. Inelastic deformation is concentrated in the shear link during a severe earthquake, and the damaged links can be replaced easily as specialized link-to-beam connections are adopted. This paper presents a series of quasi-static tests conducted to examine the seismic behavior and replaceability of the replaceable coupling beams. A total of four large-scale specimens were designed and tested, where different types of beam-to-link connections were adopted, including end plate, splice plate, bolted web, and adhesive web. All specimens fully developed the shear strength of the fuse links and showed large inelastic rotation capacity of no less than 0.06rad, except for the specimen with the adhesive web connection, which failed at an early stage. The specimen with the end plate connection had inelastic deformation concentrated in the shear link, showing very stable hysteresis behavior. Slippage of high-strength bolts was observed at the splice plate and bolted web connections, which led to increased deformation and pinching in hysteresis loops of coupling beams. Interestingly, at a coupling beam rotation exceeding 0.01rad, a large axial force developed in the steel coupling beams, the maximum value of which reached approximately a quarter to half of the axial yield strength of the shear link. In addition, on-site replacement of shear links was demonstrated after the coupling beam specimens experienced 0.02-rad rotation. The end plate connection was replaced within the shortest time, whereas the bolted web connection was able to accommodate the largest residual deformation. (C) 2016 American Society of Civil Engineers.
• Seismic Simulation of an Integrated Ceiling-Partition Wall-Piping System at E-Defense. I: Three-Dimensional Structural Response and Base Isolation

  Keri L. Ryan, Siavash Soroushian, E. Manos Maragakis, Eiji Sato, Tomohiro Sasaki, Taichiro Okazaki

  JOURNAL OF STRUCTURAL ENGINEERING 142 (2) 0733-9445 2016/02 [Refereed][Not invited]
   

  The seismic response of a full-scale, 5-story steel moment frame building in base-isolated and fixed-base configurations with an integrated suspended ceiling-partition wall-sprinkler piping system that was shaken at E-Defense is critically assessed. Horizontal floor accelerations were constrained by the isolation systems to relatively low levels, which allowed observation of damage to the integrated system that was directly related to the vertical component of input acceleration. The floor slabs exhibited single mode vibration at their natural periods with widely varying effective damping. Peak vertical accelerations were amplified by an average factor ranging from 3 to 6 from the table to the middle of the floor slabs, at which amplification factors increased as slab vibration periods lengthened. Damage to the ceiling-partion-piping components initiated at slab accelerations of approximately 2 g and became extensive for slab accelerations exceeding 5 g. These metrics establish target vertical accelerations for achieving desired performance objectives. (C) 2015 American Society of Civil Engineers.
• Cyclic Behavior of Very Short Steel Shear Links

  Xiaodong Ji, Yandong Wang, Qifeng Ma, Taichiro Okazaki

  JOURNAL OF STRUCTURAL ENGINEERING 142 (2) 04015114  0733-9445 2016/02 [Refereed][Not invited]
   

  A replaceable coupling beam is proposed comprising of steel hybrid shear links that are shorter than typical shear links in eccentrically braced frames (EBFs). Cyclic loading tests were conducted to examine the behavior of these very short shear links. The test variables included the steel type, length ratio, web stiffener configuration, and loading protocol. The link specimens showed two types of failure modes: link web fracture and fracture at the weld connecting link flange to end plate. The link specimens had an inelastic rotation capacity of approximately 0.14 rad, which is significantly larger than the capacity assumed for EBF links. Links using LY225 steel instead of Q235 steel achieved a 25% increase in inelastic rotation and 44% increase in cumulative plastic rotation. The overstrength factors of the very short shear links reached 1.9, significantly exceeding 1.5, which is the value assumed for EBF links by design provisions. Analysis suggests that large overstrength can develop in very short shear links due to the contribution of flanges and cyclic hardening of web steel under large plastic strains. In addition, axial deformation was measured as the links underwent inelastic shear deformation. (C) 2015 American Society of Civil Engineers.
• Seismic Simulation of an Integrated Ceiling-Partition Wall-Piping System at E-Defense. II: Evaluation of Nonstructural Damage and Fragilities

  Siavash Soroushian, E. Manos Maragakis, Keri L. Ryan, Eiji Sato, Tomohiro Sasaki, Taichiro Okazaki, Gilberto Mosqueda

  JOURNAL OF STRUCTURAL ENGINEERING 142 (2) 04015131  0733-9445 2016/02 [Refereed][Not invited]
   

  A full-scale, 5-story steel moment frame building in base-isolated and fixed-base configurations was subjected to a number of ground motions using the E-Defense shake table. In these experiments, more than 84 m(2) (900 ft(2)) of suspended ceiling with lay-in tiles, 90 m (300 linear ft) of partition walls with individual lengths varying from 1.5 to 9.8 m (5 to 32 ft), and three sprinkler branch lines were installed below the fifth and sixth (roof) floors of the building. Because the horizontal floor accelerations were generally constrained to relatively low values by the base isolation system, several damage states related to vertical floor system acceleration were observed. One key observation is that use of lateral bracing with compression posts did not improve the seismic response of suspended ceilings when subjected to strong vertical excitation. Acceleration amplification factors of the ceiling-partition-partition components relative to structural floor accelerations were computed. The code-prescribed amplification factors for the design of nonstructural components was consistent with the observed amplification in the horizontal direction, but unconservative in the vertical direction, because the code neglects the additional amplification produced by slab vibration. (C) 2015 American Society of Civil Engineers.
• Seismic simulation of integrated nonstructural systems at E-Defense, Part 1: Influence of 3D structural response and base isolation

  Keri L. Ryan, Siavash Soroushian, E. Manos, Maragakis, Eiji Sato, Tomohiro Sasaki, Taichiro Okazaki

  Journal of Structural Engineering, American Society of Civil Engineers 142 (2) 04015131  2016/02 [Refereed][Not invited]
  
• Improved Link-to-Column Connections for Steel Eccentrically Braced Frames

  Taichiro Okazaki, Michael D. Engelhardt, Jong-Kook Hong, Chia-Ming Uang, Apostolos Drolias

  JOURNAL OF STRUCTURAL ENGINEERING 141 (8) 04014201  0733-9445 2015/08 [Refereed][Not invited]
   

  Link-to-column connections in steel eccentrically braced frames must be capable of sustaining large cyclic forces and inelastic rotations. United States code provisions require that satisfactory performance of link-to-column connections be verified by testing under a prescribed loading protocol. However, there are few link-to-column connection details that have satisfied these testing criteria. This paper describes a pilot investigation of two promising link-to-column connection details, as follows: (1) the fillet welded connection, which uses fillet welds or a combination of fillet and groove welds between the link and the column flange; and (2) the supplemental web doubler connection, which reinforces the connection region using a pair of doubler plates in the first link web panel next to the column, parallel to but offset from the link web. These two details showed excellent performance in a series of eight tests. This paper describes these link-to-column connection details, summarizes the results of cyclic loading tests, and discusses design issues and approaches for these connections. (C) 2014 American Society of Civil Engineers.
• Link-to-Column Connection with Supplemental Web Doublers in Eccentrically Braced Frames

  Jong-Kook Hong, Chia-Ming Uang, Taichiro Okazaki, Michael D. Engelhardt

  JOURNAL OF STRUCTURAL ENGINEERING 141 (8) 04014200  0733-9445 2015/08 [Refereed][Not invited]
   

  When an eccentrically braced frame configuration requires that the links be connected to the columns, standard seismic guidelines offer little guidance on the link-to-column connection design. Recent testing showed that several welded moment connection details that have been developed after the 1994 Northridge earthquake for special moment frames still cannot prevent brittle fracture in the link flange groove welds. In support of an experimental study on the development of reliable link-to-column connection details, the supplemental web doubler connection is proposed. The connection uses a pair of partial-height doubler plates that are parallel to and offset from the web in the link panel next to the column. Finite-element analyses were conducted to guide the development of design requirements, including the minimum reinforced length, minimum supplemental doubler thickness, and weld design requirement. A closed-form solution, with some minor adjustment based on the finite-element analysis results, for the calculation of the required shear force in the supplemental doublers is also proposed. A step-by-step design procedure is presented. (C) 2014 American Society of Civil Engineers.
• Bolted beam-to-column connections for built-up columns constructed of H-SA700 steel

  Xuchuan Lin, Taichiro Okazaki, Masayoshi Nakashima

  JOURNAL OF CONSTRUCTIONAL STEEL RESEARCH 101 469 - 481 0143-974X 2014/10 [Refereed][Not invited]
   

  A research program is underway to develop a new structural system using a high-strength structural steel called H-SA700. In this system, columns are built up of H-SA700 plates using bolts only, and bolted connections are used extensively to allow structural components to be replaced or reused. Bolted beam-to-column connections using an end plate are developed for the system. Bolted stiffeners are devised to control yielding and local distortion of the column against local tension delivered by the beams. Four specimens, two with stiffeners proposed in this study and two without stiffeners, are tested under quasi-static cyclic loading. Finite element simulation is carried out to allow more detailed investigation on the yielding distribution in the connection. The specimens with the proposed stiffeners avoid the yielding and notable local distortion that occurred with the absence of the stiffeners. It is found that with the aid of the proposed stiffeners, the built-up column of H-SA700 steel would remain elastic and thus reusable even after major earthquakes. Design equations are presented to estimate the stiffness of the connection, the strength of the column against local tension, and the shear yielding of the panel zone. (C) 2014 Elsevier Ltd. All rights reserved.
• Beam-to-Column COnnections for Bolted Built-Up Columns made of H-SA700 Steel

  Kasuhiro Hayashi, Taichiro Okazaki, Xuchuan Lin, Masayoshi Nakashima

  Steel Construction Engineering, Japanese Society of Steel Construction 21 (82) 39 - 50 2014/06 [Refereed][Not invited]
  
• Stability of beams in steel eccentrically braced frames

  Gul Yigitsoy, Cem Topkaya, Taichiro Okazaki

  JOURNAL OF CONSTRUCTIONAL STEEL RESEARCH 96 14 - 25 0143-974X 2014/05 [Refereed][Not invited]
   

  When an eccentrically braced frame (EBF) is subjected to a severe seismic event, large axial force and bending moments are produced in the beam outside of the link Designers face significant difficulties in meeting the capacity design requirement to keep these beams elastic. On the other hand, previous research suggests that controlled yielding in the beams is not detrimental to EBF performance as long as stability of the beam is maintained. A computational study was undertaken to investigate the stability of cyclically loaded EBFs. A total of 51 EBF sub-assemblage models, none of which satisfies the capacity design requirement, were selected and investigated through three-dimensional, nonlinear finite element analysis. The results indicate that the link overstrength factor should be a function of the link length for performing capacity design of the beam outside of the link This is because flexure yielding links, which are more problematic to beam stability, tend to develop smaller overstrength compared to shear yielding links. Furthermore, designs with demand-to-capacity ratios greater than unity were found to be viable provided that the stability of the beam is maintained by making use of a slenderness limit developed herein. (C) 2014 Elsevier Ltd. All rights reserved.
• Effect of vertical stiffness and foundation uplift on the seismic response of building structures

  Tetsuhiro Asari, Daisuke Ujiie, Mitsumasa Midorikawa, Taichiro Okazaki

  Journal of Structural and Construction Engineering 79 (705) 1569 - 1578 1881-8153 2014 [Refereed][Not invited]
   

  Five-degrees-of-freedom models that account for uplift, rocking, and sway of the foundation, in addition to horizontal and vertical deformation of the superstructure, were used to study the beneficial effect of foundation uplift to reduce the seismic damage to building structures. The elastic models accounted for geometric nonlinearity and expressed soil-foundation interaction as a function of contact area. The nonlinear models were subjected to a suite of ground motions. The results indicated that the vertical component of ground motions does not significantly affect the horizontal response of the superstructure and that the vertical response of the superstructure is produced primarily by foundation uplift.
• Out-of-Plane Stability of Buckling-Restrained Braces Placed in Chevron Arrangement

  Tsuyoshi Hikino, Taichiro Okazaki, Koichi Kajiwara, Masayoshi Nakashima

  JOURNAL OF STRUCTURAL ENGINEERING 139 (11) 1812 - 1822 0733-9445 2013/11 [Refereed][Not invited]
   

  Large-scale shake table tests were performed at E-Defense to examine the out-of-plane stability of buckling-restrained braces (BRBs). Two specimens were subjected repeatedly to a near-fault ground motion with increasing amplification. The test specimens comprised a single-bay, single-story steel frame and a pair of BRBs placed in a chevron arrangement. The specimens were not braced at the brace-to-beam intersection in order to produce a condition where the BRBs were susceptible to out-of-plane instability. Standard BRBs were used in the first specimen, while BRBs with a flexible segment at each end of the steel core were used in the second specimen. A simple stability model predicted the BRBs in the second specimen to fail because of out-of-plane buckling. The first specimen exhibited excellent ductility during the shake table tests, while the second specimen developed severe out-of-plane deformation that compromised the ductility of the BRBs. Based on the experimental observations and the stability model, a methodology is proposed to evaluate bracing requirements at the brace-to-beam intersection.
• Experimental Performance of Steel Braced Frames Subjected to Bidirectional Loading

  Keith D. Palmer, Charles W. Roeder, Dawn E. Lehman, Taichiro Okazaki, Carol Shield

  JOURNAL OF STRUCTURAL ENGINEERING 139 (8) 1274 - 1284 0733-9445 2013/08 [Refereed][Not invited]
   

  Concentrically braced frames (CBFs) are stiff, strong systems frequently used to resist seismic loading. Special CBF (SCBF) behavior is dominated by brace buckling, while buckling restrained braced frames (BRBFs) develop tensile and compressive yielding and avoid brace buckling. Both systems are widely used in seismic design, and both have a number of specific design issues. This paper describes a first of its kind, 2-story, 1-bay by 1-bay frame tested at the University of Minnesota Network for Earthquake Engineering Simulation facility to examine the large-displacement, bidirectional behavior of SCBFs and BRBFs with realistic boundary conditions and to verify the design approach. The SCBF had rectangular hollow steel section (HSS) braces in a single-story X configuration, and the BRBF used a single-diagonal configuration. The design of the gusset plates for the HSS braces followed a previously proposed balanced design procedure with an elliptical clearance to permit out-of-plane rotation caused by brace buckling. The single-story X-brace SCBF concentrated damaged into one-half the brace length, and the first HSS brace fractured at 2% story drift. The BRBF gusset-plate design followed current design standards, and two of the BRB cores fractured at 3.6 and 4.2% story drift prior to any instability in the BRB or system. The SCBF sustained limited damage to the beams and columns; however, the BRBF had much more significant damage to these members because of larger deformations and BRBF behavior. The results indicate that these systems have a stable response to large cyclic deformations and the impact of bidirectional loading on the measured response was minimal.
• Dynamic response of a chevron concentrically braced frame

  Taichiro Okazaki, Dimitrios G. Lignos, Tsuyoshi Hikino, Koichi Kajiwara

  Journal of Structural Engineering (United States) 139 (4) 515 - 525 0733-9445 2013/04/01 [Refereed][Not invited]
   

  Large-scale shake table tests were conducted at E-Defense, Japan, to examine the dynamic response of a steel concentrically braced frame. The specimen was a single-bay, single-story frame with a pair of square hollow structural section braces placed in a chevron arrangement. The gusset plates connecting the brace to the framing elements were provided with an elliptic fold line to accommodate out-of-plane rotation of the brace in compression. The specimen was subjected repeatedly to a unidirectional ground motion with increasing magnitude until the braces buckled and eventually fractured. The bracing connections performed as intended the gusset plates folded out of plane, and no crack was observed in the gusset plate or in the critical welds. Consequently, the test results demonstrated excellent performance of the bracing connections. Elastic deformation of the beam prevented the braces from developing their full tensile strength. Yielding in the middle of the beam, which was predicted by monotonic loading analysis, did not occur. The specimen response was reproduced by a numerical model using fiber elements. This model was able to predict the occurrence of brace buckling and fracture and thereby accurately trace the dynamic behavior of the frame. © 2013 American Society of Civil Engineers.
• E-defense tests on the seismic performance of beam-to-column moment frame connections in high-rise steel buildings

  Taichiro Okazaki, Tomohiro Matsumiya, Takuya Nagae, Kunio Fukuyama, Takahito Inoue, Masayoshi Nakashima

  Journal of Structural and Construction Engineering 78 (685) 569 - 578 1340-4202 2013/03 [Refereed][Not invited]
   

  Two full-scale steel moment-resisting frames were constructed and tested at E-Defense to examine the performance of high-rise buildings subjected to long-period ground motions. Frame 1 adopted typical design and detailing from the 1970's employing both field- welded and shop-welded details for the moment frame connections. Frame 2 was identical to Frame 1 except that all connections were field-welded and upgraded using three strengthening methods. A number of connections in Frame 1 fractured during a simulated long- period motion. No damage was observed in Frame 2 until the same motion was repeated multiple times. The performance of field- welded connections in existing high-rise buildings and the effectiveness of upgrade methods are discussed.
• Damage to Steel Buildings Observed after the 2011 Tohoku-Oki Earthquake

  Taichiro Okazaki, Dimitrios G. Lignos, Mitsumasa Midorikawa, James M. Ricles, Jay Love

  EARTHQUAKE SPECTRA 29 (S1) S219 - S243 8755-2930 2013/03 [Refereed][Not invited]
   

  A joint U.S.-Japan reconnaissance team examined the damage to steel building structures caused by the 2011 Tohoku-oki earthquake. In the city of Sendai, where the peak horizontal ground acceleration exceeded 1 g, the majority of steel buildings performed well. Buildings that used older cladding systems for external finish sustained damage to their claddings even if their structural performance was excellent. Damage to a few braced frames offer insight into the seismic design of bracing connections. In areas attacked by the violent tsunami, many steel buildings stood upright after the tsunami subsided, although these buildings lost much of their external and internal finishes along with their contents. These steel buildings did not provide safe shelter for tsunami evacuation when the building submerged under the tsunami wave. A number of buildings suffered foundation failure, which was likely caused by scouring or liquefaction or a combination of multiple effects.
• Flexural performance of bolted built-up columns constructed of H-SA700 steel

  Xuchuan Lin, Taichiro Okazaki, Yu-Lin Chung, Masayoshi Nakashima

  JOURNAL OF CONSTRUCTIONAL STEEL RESEARCH 82 48 - 58 0143-974X 2013/03 [Refereed][Not invited]
   

  The H-SA700 is a new high-strength structural steel that is more environmentally friendly and more suitable for mass production than conventional high-strength steel. A research program is underway to develop a new structural steel system that extends the benefits of H-SA700 steel to achieve sustainable and seismically resilient buildings. The envisioned system uses built-up columns that are fabricated from H-SA700 plates by high-strength bolts and uses these built-up columns in weld-free construction. This paper summarizes the first phase of the program, whose objective was to establish the flexural properties of the built-up columns. Three column specimens were fabricated and subjected to cyclic lateral loading. The tests demonstrated the very large elastic deformation capacity and stable inelastic behavior of H-SA700 columns. The flexural strength was not governed by fracture of the reduced section with bolt holes, but by inelastic buckling of the flanges. The strength was limited by the plastic strength of the reduced section. The test results were used to identify the key limit states and to develop a design methodology that addresses the unique behavior of the built-up columns. Finite element simulation suggested that bolt holes help distribute yielding over a wide area of the flanges, to supply some ductility and help avoid net section fracture of the flanges. (C) 2012 Elsevier Ltd. All rights reserved.
• H-SA700 鋼を用いたボルトによる組立柱部材の曲げ性能

  林和宏, 岡崎太一郎, 林旭川, 中島正愛

  鋼構造論文集 76 (685) 569 - 578 2012/12 [Refereed][Not invited]
  
• Concentric X-braced frames with HSS bracing

  Keith D. Palmer, Charles W. Roeder, Dawn E. Lehman, Taichiro Okazaki, Carol K. Shield, Jacob Powell

  INTERNATIONAL JOURNAL OF STEEL STRUCTURES 12 (3) 443 - 459 1598-2351 2012/09 [Refereed][Not invited]
   

  Concentrically braced frames are stiff, strong systems frequently used to resist wind and seismic loading; in regions of high seismicity in the US special concentrically braced frames (SCBFs) are used. CBF configurations vary, but in low rise or other structures with modest levels of demands single-story, X-configured braced frames (X-braced) are commonly used. The brace sections used also vary but hollow structural sections (HSS) are the most common in the U.S. Although important, in part because low-rise structures sustain large demands, few research programs have focused on the single-story X-brace configuration. A large research program was undertaken to understand and improve the response of SCBFs with selected testing on single-story X braced SCBFs. The test matrix consisted of two, full-scale planar X-braced frame experiments and one nearly-full-scale three-dimensional X-braced frame. The tests were designed using a new design and detailing philosophy, called the Balanced Design Method. In this paper, application of this design method to the frame is investigated, with a focus on the center-splice connection. The results show that the ultimate inelastic deformation capacity of the system is less dependent on the specific design detail at this splice. Additionally, the bi-directional load testing indicated that the out-of-plane demands did not impact the system performance.
• Impact of Residual Stresses and Initial Imperfections on the Seismic Response of Steel Moment Frames

  Kapil Mathur, Larry A. Fahnestock, Taichiro Okazaki, Matthew J. Parkolap

  JOURNAL OF STRUCTURAL ENGINEERING-ASCE 138 (7) 942 - 951 0733-9445 2012/07 [Refereed][Not invited]
   

  The 2010 AISC specification establishes the direct analysis method (DM) as the standard stability analysis and design procedure. Although the DM has important benefits over conventional stability design methods, the interface between the DM, the AISC seismic provisions, and the seismic design requirements in ASCE-7 is not fully established. Because the DM, which was developed for design scenarios that do not contain seismic loading, includes the effects of initial geometric imperfections and inelastic behavior owing to residual stresses, it is critical to explore the impact of these parameters on the seismic behavior of typical steel buildings. To examine these issues, a series of steel special moment-resisting frame models were subjected to monotonic pushover, cyclic pushover, and response history analyses. The observed behavior was used to draw comparisons between systems with and without residual stresses and initial imperfections. Cyclic strength degradation at beam-to-column connections was also considered to examine the potential interaction it may have with the other parameters. Whereas the well-known impact of strength degradation on cyclic stability was noted, residual stresses and initial imperfections did not have any appreciable effect on stability behavior for the systems considered. The analyses conducted in this study indicate no clear benefit to using the DM when designing regular ductile steel systems in high seismic regions and simpler design methods may be equally effective. DOI: 10.1061/(ASCE)ST.1943-541X.0000512. (C) 2012 American Society of Civil Engineers.
• Local shear buckling and bearing strength in web core sandwich panels: Model and experimental validation

  Casey R. Briscoe, Susan C. Mantell, Taichiro Okazaki, Jane H. Davidson

  ENGINEERING STRUCTURES 35 114 - 119 0141-0296 2012/02 [Refereed][Not invited]
   

  A model and experimental validation of shear buckling and local bearing failure of web core sandwich panels are presented. Of particular interest are steel-faced panels with stiffening metal webs and a polymer core. The metal webs provide the required panel stiffness and the foam core serves the dual purposes of preventing local buckling and providing thermal insulation. In applications, such as the building sector, in which thermal performance is crucial, the webs are thin and widely spaced to reduce conduction between the face sheets. The models of shear buckling and bearing failure account for the influence of the core material on web strength and provide closed-form solutions. The models are validated by symmetric four-point bending tests to evaluate shear buckling and asymmetric three-point bending for bearing failure. The shear buckling model predicted buckling strength to within 4% of the test results. The bearing failure model overpredicted the observed strength by 11% on average, similar to test results reported in the literature for the bearing strength of webs with no foam support. (C) 2011 Elsevier Ltd. All rights reserved.
• Strength evaluation of composite structural connection with steel studs embedded in SFRCC slab

  K. Hoki, Y. Luo, M. Nakashima

  Journal of Structural and Construction Engineering 77 (676) 975 - 984 2012 [Refereed][Not invited]
   

  The performance of high-rise steel moment frame buildings constructed in the 1970’s is examined by using the E-Defense shake-table facility. Typical design and detailing in the 1970’s are incorporated in a four-story, steel moment frame specimen. The specimen is subjected to a series of response deformations representing a high-rise building. Long-period ground motions impose a substantial number of inelastic deformations, which eventually cause fracture in the beam-to-column connections.
• Design Procedure for Web Core Sandwich Panels for Residential Roofs

  Casey R. Briscoe, Susan C. Mantell, Jane H. Davidson, Taichiro Okazaki

  JOURNAL OF SANDWICH STRUCTURES & MATERIALS 13 (1) 23 - 58 1099-6362 2011/01 [Refereed][Not invited]
   

  Panelized construction of residential buildings is gaining popularity due to the architectural and energy efficiency benefits that can be achieved. An important challenge to the design of panel structures for buildings is the balance between long-term structural performance and the thermal insulating requirement. In this study, foam core and web core panels are designed for residential roofs. Both panels are comprised of two face sheets and an insulating foam core. In the web core panel, thin metal webs that connect the face sheets are added to improve panel shear stiffness and enable longer spans. A design procedure is developed that considers R-value, panel deflection, core shear failure, bearing failure, and buckling of the face sheets and webs. The buckling model includes the ability of the foam core stiffness to restrain the buckling deformation. Panel designs are presented that provide R-5.3 m(2) K/W for roof loads of 1500, 2000, and 3000 N/m(2), corresponding to climate zones in the US. It is demonstrated that the web core panel can be designed for these structural and thermal requirements with unsupported span lengths as long as 7 m, while span lengths for foam core panels are limited to 4 m. Web shear buckling and R-value are the two performance criteria that limit panel span length and depth.
• Nonlinear Finite-Element Analysis of Critical Gusset Plates in the I-35W Bridge in Minnesota

  Minmao Liao, Taichiro Okazaki, Roberto Ballarini, Arturo E. Schultz, Theodore V. Galambos

  JOURNAL OF STRUCTURAL ENGINEERING-ASCE 137 (1) 59 - 68 0733-9445 2011/01 [Refereed][Not invited]
   

  Reported evidence suggests that failure of gusset plates initiated the collapse of the I-35W Bridge in Minneapolis, Minnesota. The particular gusset plates were at a panel point designated as U10. Therefore, an analytical investigation was conducted on the condition of the U10 gusset plates at the time of bridge collapse. The forces delivered to panel point U10 were reproduced using available information of the bridge. These forces were introduced to detailed nonlinear three-dimensional finite-element models to calculate stress and strain states of the gusset plates. The results indicate that substantial portions of the U10 gusset plates were yielded at the time of collapse, confirming earlier findings from federal and state investigations. Weight increase due to past deck reconstruction and construction material and equipment staged on the day of collapse, along with insufficient thickness of the gusset plate, were identified as the main contributing factors to the substantial yielding. The results also suggest that the interaction of compression and shear played an important role in the gusset plate failure.
• Reduced Link Sections for Improving the Ductility of Eccentrically Braced Frame Link-to-Column Connections

  Jeffrey W. Berman, Taichiro Okazaki, Heidrun O. Hauksdottir

  JOURNAL OF STRUCTURAL ENGINEERING 136 (5) 543 - 553 0733-9445 2010/05 [Refereed][Not invited]
   

  Eccentrically braced frames (EBFs) are desirable seismic load resisting systems as they combine the high elastic stiffness of concentrically braced frames with the ductility and stable energy dissipation of moment resisting frames. EBFs with links attached to the columns are particularly appealing for architectural flexibility as they provide multiple locations for placement of doors and hallways. However, previous research has shown that link-to-column connections are prone to failure at low drift levels, due to their susceptibility to fracture at the link flange-to-column welds. This paper investigates the application of the reduced beam section concept for links in eccentrically braced frames to enhance the ductility of link-to-column connections. A design procedure for link section reduction is proposed and preliminary finite-element analyses are conducted on a shear link with various reduced section geometries. A parametric study performed on an array of links having various cross sections and lengths suggests that the reduced link section may substantially reduce the plastic flange strains at the link ends, which can improve the fracture life. The reduction in plastic flange strains is found to be significant for all links, with larger reductions for intermediate and flexural links. Furthermore, the detrimental kinking deformation of the flanges, caused by the large rotation demands in shear links, is moved away from the column face when reduced sections were used. While the analysis results show promise, experimental verification is recommended before the proposed design procedure can be implemented in practice.
• Web crippling strength of a steel sandwich panel with V-shaped webs

  Taichiro Okazaki, Brian J. Siljenberg, Carol K. Shield, Susan C. Mantell

  JOURNAL OF CONSTRUCTIONAL STEEL RESEARCH 65 (8-9) 1721 - 1730 0143-974X 2009/08 [Refereed][Not invited]
   

  Steel sandwich panels with V-shaped web flutes (V-core panels) serve the structural functions of a proposed energy-efficient roof system for residential construction. Due to its intended use as a flexural member spanning between a ridge beam and a structural wall, and required slender webs for weight considerations, web crippling under end one-flange loading is a critical strength limit state for the V-core panels. Although the 2001 North American Specification for the Design of Cold-Formed Steel Structural Members provides a design procedure to address web crippling, those design rules were developed for members whose cross sections are different from that of V-core panels. Consequently, nine specimens were tested to collect data on V-core panels subjected to end one-flange loading. Test observations suggested that V-core panels behave very similarly to multi-web decks that are strapped and unfastened to the supports. Experimental data reported in the literature was used to modify the web crippling strength equation in the Specification to reflect these particular conditions. The modified equation was found to adequately predict the measured web crippling strength of V-core panels. (C) 2009 Elsevier Ltd. All rights reserved.
• Experimental investigation of link-to-column connections in eccentrically braced frames

  Taichiro Okazaki, Michael D. Engelhardt, Apostolos Drolias, Eric Schell, Jong-Kook Hong, Chia-Ming Uang

  JOURNAL OF CONSTRUCTIONAL STEEL RESEARCH 65 (7) 1401 - 1412 0143-974X 2009/07 [Refereed][Not invited]
   

  The design of link-to-column connections in seismic-resistant eccentrically braced frames remains a largely unresolved problem. In order to address this problem, twenty-four large-scale specimens were tested under cyclic loading. The test parameters included the connection detail, link length, link section, and cyclic loading protocol. The test results suggest that link-to-column connections are susceptible to fracture at the link flange welds, regardless of the link length. A large number of specimens failed prematurely, before meeting the plastic link rotation requirement in US code provisions. However, two promising link-to-column connection details were developed as an outcome of this research. The new connection details include a detail using all-around fillet welds between the link and the column flange, and a reinforced connection detail that welds a pair of stiffeners in the first link web panel next to the column, parallel to the link web. Test specimens using either of these two details were able to exceed the plastic link rotation requirement. (c) 2009 Elsevier Ltd. All rights reserved.
• Cyclic loading behavior of EBF links constructed of ASTM A992 steel

  Taichiro Okazaki, Michael D. Engelhardt

  JOURNAL OF CONSTRUCTIONAL STEEL RESEARCH 63 (6) 751 - 765 0143-974X 2007/06 [Refereed][Not invited]
   

  Cyclic loading tests were conducted to study the behavior of link beams in steel eccentrically braced frames. A total of thirty-seven link specimens were constructed from five different wide-flange sections, all of ASTM A992 steel, with link length varying from short shear yielding links to long flexure yielding links. The occurrence of web fracture in shear yielding link specimens led to further study on the cause of these fractures. Since the link web fracture appeared to be a phenomenon unique to modern rolled shapes, the potential role of material properties on these fractures is discussed. Based on the test data, a change in the flange slenderness limit is proposed. The link overstrength factor of 1.5, as assumed in the current U.S. code provisions, appears to be reasonable. The cyclic loading history used for testing was found to significantly affect link performance. Test observations also suggest new techniques for link stiffener design and detailing for link-to-column connections. (c) 2006 Elsevier Ltd. All rights reserved.
• Interaction between cladding and structural frame observed in a full-scale steel building test

  Taichiro Okazaki, Masayoshi Nakashima, Keiichiro Suita, Tomohiro Matusmiya

  EARTHQUAKE ENGINEERING & STRUCTURAL DYNAMICS 36 (1) 35 - 53 0098-8847 2007/01 [Refereed][Not invited]
   

  Interaction between the external wall cladding and the seismic load resisting frame was examined in a full-scale cyclic loading test of a three-storey steel building structure. The building specimen had Autoclaved Lightweight Concrete (ALC, also designated as Autoclaved Aerated Concrete) panels installed and anchored to the structural frame as external wall cladding, using a standard Japanese method developed following the 1995 Kobe earthquake. ALC panelling is among the most widely used material for claddings in Japan. In the test, the ALC panel cladding contributed little to the stiffness and strength of the overall structure, even under a very large storey drift of 0.04 rad. No visible damage was noted in the ALC panels other than minor cracks and spalling of the bottom of the panels In the first storey. Consequently, in a Japanese steel building with properly installed ALC panel cladding, the structural frame is likely to be little affected by its cladding, and the ALC panels are capable of accommodating the maximum storey drift generally considered in structural design without sustaining discernible damage. Copyright (C) 2006 John Wiley & Sons, Ltd.
• Impact of recent research findings on eccentrically braced frame design

  Paul Richards, Taichiro Okazaki, Michael Engelhardt, Chia-Ming Uang

  ENGINEERING JOURNAL-AMERICAN INSTITUTE OF STEEL CONSTRUCTION INC 44 (1) 41 - 53 0013-8029 2007 [Refereed][Not invited]
  
• Stability requirements for beams in seismic steel moment frames

  Taichiro Okazaki, Dawei Liu, Masayoshi Nakashima, Michael D. Engelhardt

  JOURNAL OF STRUCTURAL ENGINEERING-ASCE 132 (9) 1334 - 1342 0733-9445 2006/09 [Refereed][Not invited]
   

  An analytical study was conducted on the cyclic loading behavior of beams in steel moment frames. Lateral-torsional buckling and local buckling were explicitly considered in the analysis. Beam cross-sectional dimensions were varied to represent a wide range of rolled wide flange shapes. The unbraced length of the beams corresponded to slenderness ratios about the weak axis ranging between 60 and 100. Based on the analyses, flange and web width-thickness limits were established that would permit the beam to achieve various target rotation capacities. These limits are presented in terms of limit curves which plot the flange width-thickness ratio against the web width-thickness ratio. The limit curves clearly show strong flange-web interaction. Different limit curves were developed for a range of target rotation angles, weak axis slenderness ratios, and residual strength levels. Postbuckling behavior and strength degradation mechanism were studied. The results of the analyses are compared against current building code requirements for beam stability in seismic steel moment frames, and the adequacy of the current code requirements are evaluated.
• Experimental performance of link-to-column connections in eccentrically braced frames

  Taichiro Okazaki, Michael D. Engelhardt, Masayoshi Nakashima, Keiichiro Suita

  JOURNAL OF STRUCTURAL ENGINEERING ASCE-AMER SOC CIVIL ENGINEERS 132 (8) 1201 - 1211 0733-9445 2006/08 [Refereed][Not invited]
   

  A total of 12 large-scale link-column specimens were tested to study the cyclic loading performance of link-to-column connections in eccentrically braced frames. Four different link-to-column connection types with varying configuration and welding details were tested. Each of the four connection types was tested with three different link lengths to consider a wide range of force and deformation environments at the link-to-column connection. The specimens representing the pre-Northridge practice failed after developing only half of the inelastic link rotation required in U.S. building codes. Additional connection types were tested that implemented improved welding practices, as well as specimens that implement design and detailing modifications. This included connections that used the free flange concept and connections that eliminated the weld access holes. The experimental program and key test results are presented in this paper.
• Experimental study of local buckling, overstrength, and fracture of links in eccentrically braced frames

  T Okazaki, G Arce, HC Ryu, MD Engelhardt

  JOURNAL OF STRUCTURAL ENGINEERING-ASCE 131 (10) 1526 - 1535 0733-9445 2005/10 [Refereed][Not invited]
   

  A total of 23 tests were conducted to study the cyclic loading performance of links in steel eccentrically braced frames. The objectives of these tests were to reevaluate flange slenderness limits and overstrength factors for links. The effect of loading history on link performance was also investigated. Link specimens were constructed from five different wide-flange sections, all of ASTM A992 steel, with various lengths ranging from short shear yielding links to very long flexural yielding links. In addition to providing data on the effects of flange buckling and overstrength, these tests also showed some unexpected failure modes. The paper provides an overview of this experimental investigation, describing the overall research program, as well as details of the test specimens and test results. The paper concludes with a number of design recommendations for links in eccentrically braced frames.
• 米国信頼性耐震設計の概要と梁の塑性変形能力の確率的評価の日米比較

  日下彰宏, 加登美喜子, 岡崎太一郎

  鋼構造論文集、日本鋼構造協会 12 (45) 9 - 24 2005/03 [Refereed][Not invited]
  
• 柱梁接合部の設計規範と構造性能に関する日米比較

  松本由香, 浅井英克, 岡崎太一郎

  鋼構造論文集、日本鋼構造協会 12 (45) 87 - 100 2005/03 [Refereed][Not invited]
  
• Collaboration between practice and research for development of steel construction in Japan.

  Masayoshi Nakashima, Mikiko Kato, Taichiro Okazaki

  International Journal of Steel Structures, Korean Society of Steel Construction 4 (4) 249 - 262 2004/12 [Refereed][Not invited]
  
• Longitudinal elastic waves in columns due to earthquake motion

  T Nonaka, RJ Clifton, T Okazaki

  INTERNATIONAL JOURNAL OF IMPACT ENGINEERING 18 (7-8) 889 - 898 0734-743X 1996/10 [Refereed][Not invited]
   

  An analysis is presented of longitudinal waves in a thin elastic column. Velocity is specified at one end, and the boundary condition at the other end is expressed in terms of a range of effective impedances of an attached structure. Propagation, reflection and interference of the waves are followed by the method of characteristics. Integration of differential equations along characteristics yields the wave-induced stress, which is then applied to problems of earthquake excitation. Numerical examples are given for recorded updown ground motion of the Kobe Earthquake. Copyright (C) 1996 Elsevier Science Ltd.

MISC

• 3-D detailed finite element analysis of full-scale shaking table rest on a 10-story steel building

  Jun Fujiwara, Takuya Nagae, Tianhao Yan, Jialiang Jin, Jionghui Li, Taichiro Okazaki, Akiko Kishida, Ryota Nishi, Koichi Kajiwara  18th World Conference on Earthquake Engineering (18WCEE)  2024/07  [Refereed][Not invited]
  
• Panel zone and column response in a shake-table test on a 10-story steel moment-resisting frame

  Jionghui Li, Taichiro Okazaki, Jun Fujiwara, Koichi Kajiwara, Akiko Kishida, Ryota Nishi, Takuya Nagae, Jialiang Jin, Tatsuya Asai  18th World Conference on Earthquake Engineering (18WCEE)  2024/07  [Refereed][Not invited]
  
• Effective width of slab for composite beam at joint region

  Masaki Arita, Yuichi Nishida, J.Y. Richard Liew, Taichiro Okazaki  11th International Conference on Behavior of Steel Structures in Seismic Areas (STESSA 2024)  2024/07  [Refereed][Not invited]
  
• Shake-table collapse tests of a reduced-scale, 4-story steel moment resisting frame

  Martin Somarriba, Jionghui Li, Taichiro Okazaki, Takuya Nagae, Tomohiro Matsumiya  11th International Conference on Behavior of Steel Structures in Seismic Areas (STESSA 2024)  2024/07  [Refereed][Not invited]
  
• Numerical simulation of a reduced-scale, 4-story steel moment-resisting frame tested to collapse

  Jionghui Li, Martin Somarriba, Taichiro Okazaki, Takuya Nagae, Ryota Matsui  11th International Conference on Behavior of Steel Structures in Seismic Areas (STESSA 2024)  2024/07  [Refereed][Not invited]
  
• Experimental investigation of cyclic loading performance of stubby steel braces

  Ryota Matsui, Yoshihiro Abe, Ibrahim Abiodun Raheem, Naoki Sadanaga, Ilanildo Dias, Taichiro Okazaki  11th International Conference on Behavior of Steel Structures in Seismic Areas (STESSA 2024)  2024/07  [Refereed][Not invited]
  
• Force limiting connections to mitigate accelerations in moment resisting frames with pinned-base spines

  Jessica Duncan (Duke, Bryam Astudillo, Richard Sause, James Ricles, Larry Fahnestock, Barbara Simpson, Masahiro Kurata, Yohsuke Kawamata, Taichiro Okazaki, Zhuoqi Tao, Yi Qie  11th International Conference on Behavior of Steel Structures in Seismic Areas (STESSA 2024)  2024/07  [Refereed][Not invited]
  
• Scientific and educational impact of experimental research

  Taichiro OKAZAKI  Structure、JSCA  (171)  36  -37  2024/07  [Invited]
  
• Residual performance and geometric imperfection of structural steels after plastic deformation and strain aging

  Haruna Nakagawa, Fumika Arai, Shaoqi Yang, Taichiro Okazaki  Proceedings of Constructional Steel, Japan Society of Steel Construction  30-  497  -506  2022/12  [Refereed]
  
• 主題解説 (3) 米国の鋼構造規準の現状

  『JIS A 3305から見た国内構造基準の課題と荷重規定』構造部門（荷重）パネルディスカッション資料、2022年度日本建築学会大会（北海道）  13  -18  2022/09
• Shake Table Tests to Examine the Seismic Performance of Prefabricated Steel Unit Houses

  Ryosuke Matsuda, Taichiro Okazaki, Takuya Nagae, Tomohiro Matsumiya, Yoshikazu Kanzaki, Takahiro Fukui, Toshihiko Iijima, Yoshiro Kiriyama, Koichi Kajiwara  Lecture Notes in Civil Engineering, STESSA 2022: Proceedings of the 10th International Conference on Behaviour of Steel Structures in Seismic Areas  1116  -1123  2022/05  [Refereed]
  
• Frame-Spine System with Force-Limiting Connections for Low-Damage Seismic-Resilient Buildings

  Larry Fahnestock, Richard Sause, James Ricles, Barbara Simpson, Masahiro Kurata, Taichiro Okazaki, Yohsuke Kawamata, Zhuoqi Tao, Jessica Duke, David Rivera, Bryam Astudillo, Yi Qie  Lecture Notes in Civil Engineering  804  -811  2022/05  [Refereed]
  
• Numerical Response Estimations of a Frame-Spine-FLC System Prior to Experimental Dynamic Testing

  Bryam Astudillo, David Rivera, Barbara Simpson, Larry Fahnestock, Richard Sause, James Ricles, Masahiro Kurata, Taichiro Okazaki, Yohsuke Kawamata, Zhuoqi Tao, Jessica Duke, Yi Qie  Lecture Notes in Civil Engineering, STESSA 2022: Proceedings of the 10th International Conference on Behaviour of Steel Structures in Seismic Areas  370  -378  2022/05  [Refereed]
  
• A Database for Steel Braces with Respect to Inelastic Strength and Ductility Capacity

  Ryota Matsui, Zhang Yiyue, Taichiro Okazaki, Toru Takeuchi  Lecture Notes in Civil Engineering, STESSA 2022: Proceedings of the 10th International Conference on Behaviour of Steel Structures in Seismic Areas  216  -223  2022/05  [Refereed]
  
• Residual Performance of Structural Steel After Cyclic Plastic Deformation and Strain Aging

  Haruka Nakagawa, Kayo Taniguchi, Shaoqi Yang, Tetsuhiro Asari, Taichiro Okazaki  Lecture Notes in Civil Engineering, STESSA 2022: Proceedings of the 10th International Conference on Behaviour of Steel Structures in Seismic Areas  157  -165  2022/05  [Refereed]
  
• Report on Future Direction Sessions in the 17th World Conference on Earthquake Engineering

  Masayuki Kohiyama, Taichiro Okazaki, Mitsuyoshi Akiyama, Tsuyoshi Ichimura  JAEE Newsletter  11-  (1)  18  -23  2022/04  [Not refereed][Not invited]
  
• STUDY ON FRAGILITY FUNCTION UPDATING FOR PARTITION WALL USING IMAGE PROCESSING AND MONITORING SYSTEM

  Mai UMEBAYASHI, Noriyuki TAKAHASHI, Hiroyuki CHIDA, Takuya NAGAE, Taichiro OKAZAKI, Tomohiro MATSUMIYA, Koichi KAJIWARA, Hiroshi NAKAZAWA, Yoshikazu KANZAKI  Journal of Structural Engineering B  68B-  261  -270  2022/04  [Refereed]
  
• 修業時代を振り返って

  岡崎太一郎  日本免震構造協会会誌MENSHIN  (115)  1  -3  2022/01  [Not refereed][Invited]
  
• 米国のブレース構造 ―日本と違った設計法・構造計画・考え方―（特集：ブレース材・制振部材を活かした構造デザイン）

  岡崎太一郎  鉄鋼技術  33-  (389)  48  -51  2020/10  [Not refereed][Invited]
  
• Computational study on the seismic behavior of steel chevron braced frames in Japan

  Ilanildo Dias, Akiri Seki, Taichiro Okazaki  17th World Conference on Earthquake Engineering  Paper No. C001293  2020/09  [Not refereed][Not invited]
  
• Residual performance of structural steel beams after plastic deformation and strain aging

  Kayo Taniguchi, Shaoqi Yang, Taichiro Okazaki, Tetsuhiro Asari  17th World Conference on Earthquake Engineering  Paper No. C004120  2020/09  [Not refereed][Not invited]
  
• Numerical simulation of fracture propagation in high-rise buildings subjected to long period-long duration earthquakes.

  Taichiro Okazaki, Akiri Seki, Hashini Herath, Takuya Nagae  17th World Conference on Earthquake Engineering  Paper No. C004008  2020/09  [Not refereed][Not invited]
  
• 主題解説 (1) 学会規準・指針の成立経緯

  緑川光正, 松井良太, 岡崎太一郎  『日本の鋼構造設計を世界に知ってもらうために』構造部門（鋼構造）パネルディスカッション資料、2019年度日本建築学会大会（北陸）  4  -11  2019/09  [Not refereed]
  
• 主題解説 (6) 世界に知ってもらうために

  岡崎太一郎  『日本の鋼構造を世界に知ってもらうために』構造部門（鋼構造）パネルディスカッション資料  49  -57  2019/09  [Not refereed][Not invited]
  
• A computational study on the cyclic loading behavior of steel chevron braced frames

  Ilanildo Dias, Akiri Seki, Taichiro Okazaki  15th Japan Earthquake Engineering Symposium  777  -784  2018/12  [Not refereed][Not invited]
  
• Experimental behavior of chevron braced frames designed according to current practice

  Akiri Seki, Taichiro Okazaki, Ilanildo Dias, Hayato Asada  15th Japan Earthquake Engineering Symposium  795  -803  2018/12  [Not refereed][Not invited]
  
• Experimental performance of chevron steel braced frames using I-section braces.

  Akiri Seki, Shuhei Usesugi, Taichiro Okazaki, Hayato Asada, Tetsuhiro Asari  Proceedings of Constructional Steel, Japan Society of Steel Construction  26-  196  -203  2018/11  [Not refereed][Not invited]
  
• 環境配慮設計の現状と課題

  岡崎太一郎  『東京五輪を契機に鋼構造環境配慮設計をどのように次世代に引き継ぐか』構造部門（鋼構造）パネルディスカッション資料  4  -9  2018/09  [Not refereed][Not invited]
  
• Cyclic loading behavior of steel chevron braced frames with round-hollow-section or I-section braces

  Taichiro Okazaki, Akiri Seki, Hayato Asada  16th European Conference on Earthquake Engineering  Paper No. 11271  2018/06  [Not refereed][Not invited]
  
• Now Available: English Translation of the 2005 AIJ Design Standard for Steel Structures

  Taichiro OKAZAKI  Steel Construction Today & Tomorrow  52-  3  -4  2017/12  [Not refereed][Not invited]
  
• An Experimental study of adhesively joined steel beam splices subject to combined shear and flexure Part 2

  Yosuke Watanabe, Haruna Takano, Taichiro Okazaki, Hisakazu Hori, Tetsuhiro Asari  Proceedings of Constructional Steel, Japan Society of Steel Construction  25-  602  -609  2017/11  [Refereed][Not invited]
  
• An Experimental Study on the Application of Structural Adhesive in Steel Connections

  Haruna Takano, Yosuke Watanabe, Taichiro Okazaki, Tadayoshi Okada, Shinpei Terada  Proceedings of Constructional Steel, Japan Society of Steel Construction  25-  594  -601  2017/11  [Refereed][Not invited]
  
• Experimental Performance of Chevron Steel Braced Frames

  kiri Seki, Shuhei Usesugi, Taichiro Okazaki, Hayato Asada, Tetsuhiro Asari  鋼構造年次論文報告集、日本鋼構造協会  25-  841  -848  2017/11  [Refereed][Not invited]
  
• Seismic response of structures that permit foundation uplift

  Kasushi Nakata, Tetsuhiro Asari, Taichiro Okazaki, Mitsumasa Midorikawa  Journal of Structural Engineering, Architectural Institute of Japan  63B-  351  -358  2017/04  [Refereed][Not invited]
  
• Failure mode, overstrength ration in compression, and energy dissipation capacity of buckling-restrained braces

  Taichiro OKAZAKI  Journal of Structural Engineering, Architectural Institute of Japan  63B-  543  -552  2017/04  [Refereed][Not invited]
  
• Cyclic loading performance of full-scale special truss moment frame with innovative details for high seismic activity

  Chatchai Jiansinlapadamrong, Sanputt Simasathien, Taichiro Okazaki, Shih-Ho Chao  16th World Conference on Earthquake Engineering (16WCEE)  No. 2914  2017/01  [Not refereed][Not invited]
  
• Seismic Diagnosis and Damage Prediction of Existing Building in Hokkaido

  山﨑 翔, 緑川 光正, 岡崎 太一郎, 麻里 哲広  北海道地区自然災害科学資料センター報告 = Bulletin of the Natural Disaster Science Data Center, Hokkaido  29-  35  -58  2016/03
• An Experimental study of adhesively joined steel beam splices subject to combined shear and flexure

  Keisuke INOUE, Taichiro OKAZAKI, Hisakazu HORII Mitsumasa MIDORIKAWA, Tetsuhiro ASARI  Proceedings of Constructional Steel  23-  262  -269  2015/11  [Refereed][Not invited]
  
• 013 Survey on the design of steel concentrically braced frames in Hokkaido

  Okazaki Taichiro, Midorikawa Mitsumasa, Asari Tetsuhiro  日本建築学会北海道支部研究報告集  (88)  55  -60  2015/06/27
• Modified structural layouts for Staggered Truss Framing systems used in seismically active areas

  S. Simasathien, S. H. Chao, K. Moore, T. Okazaki  NCEE 2014 - 10th U.S. National Conference on Earthquake Engineering: Frontiers of Earthquake Engineering  No. 1126  2014  [Not refereed][Not invited]
   

  The steel Staggered Truss Framing (STF) system is a highly economical and efficient steel framing system that accommodates generic architectural and structural requirements for mid- to high-rise buildings. Due to the attributes of enabling small floor-to-floor height, large column-free spaces, reduced number of columns, efficient use of material, light weight, reduced size and load requirements for the foundation, high lateral stiffness, rapid construction, and low overall cost, STFs have become a popular system in regions of low seismicity. Although STFs were originally developed for low seismic regions, the high lateral stiffness and light weight make this system attractive for use in high seismic regions. However, very limited studies have been conducted on the behavior of STFs under strong earthquake ground motions. A key to the lateral-load resisting mechanism of STFs is the active participation of the floor diaphragms (typically consists of prestressed hollow-core planks) to transfer the inertial forces cumulating in a staggered manner across the height of the structure. The increasingly large diaphragm shear force in the lower stories brings concerns regarding the cyclic behavior of diaphragm-to-truss connections, local stress demand in the diaphragms under in-plane force and out-of-plane displacement. The stability of the system needs to be investigated if the trusses are designed to take inelastic action since the trusses serve as both the gravity and lateral-load resisting systems. In this paper, limitations of the conventional STF for use in seismically active areas are discussed. Subsequently, an alternative structural layout was investigated in which the conventional diaphragms composed of precast concrete panels are replaced by horizontal steel trusses to transmit the large diaphragm shears in the lower stories. A prototype mid-rise STF building was designed according to the spectrum specified in ASCE-7 and the seismic performance of the 3-D model was evaluated by nonlinear time-history analyses.
• Cyclic loading performance of special truss moment frame with double-channel chord members

  S. Simasathien, C. Jiansinlapadamrong, T. Okazaki, S. H. Chao  NCEE 2014 - 10th U.S. National Conference on Earthquake Engineering: Frontiers of Earthquake Engineering  No. 1109  2014  [Not refereed][Not invited]
   

  Special truss moment frame (STMF) is a relatively new type of steel framing system for use in high seismic areas. STMFs dissipate earthquake energy through ductile special segments located near the mid-span of the truss girders, while the other members outside the special segment, including truss members, columns, and girder-to-column connections, are designed to remain elastic. When an STMF is subjected to seismic forces, the induced shear force, V< inf> ne< /inf> , in the middle of the truss girder is resisted primarily by the chord members in the special segment. One of the major advantages of using the STMF system is that the truss girders can be economically used over longer spans, and greater overall structural stiffness can be achieved by using deeper girders. In addition, the open-webs can easily accommodate mechanical and electrical ductwork. As a consequence, this system offers a wide range of structural, architectural, and economical benefits due to their ability to achieve a large column-free floor. Research work carried out on STMFs with angle sections as chord members during the 1990s led to the formulation of design code provisions. However, previous tests on STMFs did not adequately reflect the current practice in design and detailing where much heavier sections are needed for chord members. Substantial improvement in design methodology and confidence could be gained for STMFs by further research. In this paper, preliminary test results of a National Science Foundation (NSF) Network for Earthquake Engineering Simulation (NEES) project on two of the full-scale STMF specimens with double-channel chord members are discussed. The goals of the experiments are to verify the behavior of STMFs designed and constructed according to recommendations from the latest American Institute of Steel Construction (AISC) Seismic Provisions as well as to investigate the innovative detailing used in designing the truss members.
• Performance of triple-pendulum bearings observed in a full-scale shake-table test program

  T. Okazaki, E. Sato, K. Ryan, T. Sasaki, S. Mahin  NCEE 2014 - 10th U.S. National Conference on Earthquake Engineering: Frontiers of Earthquake Engineering  No. 114  2014  [Not refereed][Not invited]
   

  A full-scale, steel moment-frame building, whose base was seismically isolated using nine triple-pendulum bearings (TPBs), was subjected to a number of horizontal and horizontal-plus-vertical ground motions using the E-Defense shake table. The tests demonstrated excellent performance of the base-isolation system against ground motions with different characteristics ranging from large high-frequency content, large vertical acceleration, to long duration. After experiencing 20 severe ground motions, the TPBs exhibited the same performance as they did in the first ground motion. Large variation in vertical forces, produced by overturning moment in the building and vertical ground acceleration, caused instantaneous disturbance to individual TPBs but had limited influence on the performance of the isolation system. Motions with extremely large vertical acceleration caused uplift in the TPBs of up to 20 mm. The uplift was followed by an impact that produced a large compression spike in the TPBs. The impact did not damage the TPBs and caused little influence on the hysteretic behavior of the TPBs. A height difference as large as 7 mm was recorded between the TPBs, but the difference reduced to below 3 mm when the horizontal displacement receded.
• 第15回世界地震工学会議参加報告

  小檜山雅之, 岡崎太一郎  日本地震工学会誌  (18)  88  -91  2013/01
• 鉄骨造の接合部を設計する III章 接合部のディテール 柱脚のディテール 露出柱脚の設計と性能

  岡崎太一郎  建築技術  (754)  122-123  -159  2012/11/01  [Not refereed][Not invited]
  
• Japanese research on super-high-strength structural steel

  Taichiro Okazaki, Fukami Hidenori, Masato Ohata, Masayoshi Nakashima  North American Steel Construction Conference (NASCC)  2012/04  [Not refereed][Invited]
  
• Damage to Buildings Observed from the March 11, 2011 Tohoku Earthquake

  緑川 光正, 岡崎 太一郎  北海道地区自然災害科学資料センター報告  25-  30  -75  2012/03  [Not refereed][Not invited]
  
• 鋼構造建物の大型振動実験の今とこれから : 鋼構造設計施工の高度化と合理化に向けて(構造部門(鋼構造),パネルディスカッション,2010年度日本建築学会大会(北陸)の概要)

  岡崎 太一郎  建築雑誌  126-  (1614)  43  -43  2011/02/20  [Not refereed][Not invited]
  
• Out-of-plane stability of buckling-restrained braces

  T. Hikino, T. Okazaki, K. Kajiwara, M. Nakashima  Structures Congress 2011 - Proceedings of the 2011 Structures Congress  938  -949  2011  [Refereed][Not invited]
  
• Reduced link sections for improving the ductility of eccentrically braced frame link-to-column connections

  Jeffrey W. Berman, Taichiro Okazaki, Heidrun O. Hauksdottir  9th US National and 10th Canadian Conference on Earthquake Engineering 2010  3546  -3555  2010/07  [Refereed][Not invited]
  
• On the interface of stability and seismic design requirements for steel buildings

  Taichiro Okazaki, Larry A. Fahnestock, Matthew Parkolap  Structural Stability Research Council - Annual Stability Conference  271  -290  2010/05
• ミネソタの一面

  岡崎 太一郎, 尾上 博一  コンクリート工学 = Concrete journal  46-  (11)  66  -67  2008/11/01  [Not refereed][Not invited]
  
• ミネソタ大学MAST装置を使った研究

  岡崎太一郎  震災予防  (216)  26  -31  2007/09
• Finite element simulation of link-to- column connections in steel eccentrically braced frames

  Taichiro Okazaki, Michael D. Engelhardt  100th Anniversary Earthquake Conference commemorating the 1906 San Francisco Earthquake (Eighth National Conference on Earthquake Engineering)  2006/08  [Refereed]
  
• 22349 Cyclic loading behavior of link members constructed of ASTM A992 steel

  Okazaki Taichiro, Engelhardt Michael D  Summaries of technical papers of Annual Meeting Architectural Institute of Japan. C-1, Structures III, Timber structures steel structures steel reinforced concrete structures  2005-  (0)  697  -698  2005/07/31  [Not refereed][Not invited]
  
• Impact of recent research findings on eccentrically braced frame (EBF) design

  Paul Richards, Chia-Ming Uang, Taichiro Okazaki, Michael D. Engelhardt  Structural Engineers Association of California (SEAOC) Convention 2004  2004/08  [Not refereed]
  
• Experimental study on link-to-column connections in steel eccentrically braced frames

  Taichiro Okazaki, Michael D. Engelhardt, Masayoshi Nakashima, Keiichiro Suita  The Thirteenth World Conference on Earthquake Engineering  2004/08  [Refereed]
  
• Recent research on link performance in steel eccentrically braced frames

  Taichiro Okazaki, Gabriela Arce, Michael D. Engelhardt  The Thirteenth World Conference on Earthquake Engineering  2004/08  [Refereed]
  
• Behaviour of link-to-column connections in steel eccentrically braced frames

  Taichiro Okazaki, Michael D. Engelhardt, Masayoshi Nakashima, Keiichiro Suita, K.-C. Tsai  Fourth International Conference on Behavior of Steel Structures in Seismic Areas (STESSA 2003)  351  -356  2003/06  [Refereed]
  
• Experimental behaviour of shear and flexural yielding links of ASTM A992 steel

  Gabriela Arce, Taichiro Okazaki, Michael D. Engelhardt  Fourth International Conference on Behavior of Steel Structures in Seismic Areas (STESSA 2003)  107  -113  2003/06  [Refereed]
  
• UC Berkeley - CUREE Symposium in Honor of Ray Clough and Joseph Penzien

  岡崎太一郎, 中島正愛  震災予防  (185)  1  -2  2002/07
• Elasto-Plastic Behavior of Thin-Walled Members under Repeated Axial Loading

  OKAZAKI Taichiro, NONAKA Taijiro  Summaries of technical papers of Annual Meeting Architectural Institute of Japan. C-1, Structures III, Timber structures steel structures steel reinforced concrete structures  1996-  (0)  817  -818  1996/07/30  [Not refereed][Not invited]
  
• 2055 Elasto-Plastic Behavior of Thin-Walled Members under Repeated Axial Loading

  OKAZAKI Taichiro, NONAKA Taijiro  日本建築学会近畿支部研究報告集. 構造系  0-  (36)  233  -236  1996/07/03  [Not refereed][Not invited]
  

Books etc

• AIJ Standard for Allowable Stress Design of Steel Structures

  Taichiro OKAZAKI (Joint workChapters 1 to 6)
  Maruzen 2019/10
• AIJ Design Standard for Steel Structures ― Based on Allowable Stress Concept― (2005 Edition)

  Taichiro OKAZAKI (Joint translationChapers 1 to 4)
  Architectural Institute of Japan 2017/10
• AIJ Recommendations for Plastic Design of Steel Structures

  Taichiro OKAZAKI (Joint workChapter 7)
  Maruzen 2017/02
• Recommendations for Sustainable Steel Building Construction (Draft) ―Member Reuse―

  Taichiro OKAZAKI (Joint workSections 2.2 and 4.1)
  Maruzen 2015/12
• JSSC Sets of Torshear Type High-Strength Bolt, Hexagon Nut and Plain Washer for structural Joints (English translation)

  Taichiro OKAZAKI (Joint work全体)
  Japanese Society of Steel Construction

Presentations

• Seismic Performance of Steel Beam-to-Column Moment Connections in Japan  [Invited]

  Taichiro Okazaki

  Tianjin University / National Facility for Earthquake Engineering Simulation  2020/11
• 地震と鋼材―阪神・淡路大地震から25年を過ぎて―  [Invited]

  岡崎太一郎

  第71回白石記念講座  2019/11
• Contribution of Academic Research to the Seismic Safety of Steel Structures in Japan.  [Invited]

  Taichiro OKAZAKI

  16th Symposium on Earthquake Engineering (India)  2018/12
• Seismic Design Procedure of Steel Structures in Japan: Past, Present, and Future  [Invited]

  Taichiro OKAZAKI

  Nagoya Institute of Technology International Symposium (2018)  2018/09
• Japanese Research on Super-High-Strength Structural Steel  [Invited]

  Taichiro OKAZAKI, Hidenori FUKAMI, Masato OHATA, Masayoshi NAKASHIMA

  NASCC: The Steel Conference  2012/04

Teaching Experience

SDGs Seminar: International Colearning PBL for Problem SolvingSDGs Seminar: International Colearning PBL for Problem Solving Hokkaido University
Steel Design IISteel Design II Hokkaido University
Exercise in Building Materials (Team taught)Exercise in Building Materials (Team taught) Hokkaido University
Advanced Structural AnalysisAdvanced Structural Analysis Hokkaido University
Structural Steel Members and SystemsStructural Steel Members and Systems Hokkaido University
Structural Mechanics 2Structural Mechanics 2 Hokkaido University
Structural Mechanics 1Structural Mechanics 1 Hokkaido University
Introduction to Architectural Engineering (co-taught)Introduction to Architectural Engineering (co-taught) Hokkaido University
Freshman Seminar: Material and Mechanics of Structures (co-taught)Freshman Seminar: Material and Mechanics of Structures (co-taught) Hokkaido University
Structural Mechanics 3Structural Mechanics 3 Hokkaido University
Structural Analysis IStructural Analysis I Hokkaido University
Mathematics in Architectural EngineeringMathematics in Architectural Engineering Hokkaido University
Dynamics of Building StructuresDynamics of Building Structures Hokkaido University
Seminars in Architectural Engineering IISeminars in Architectural Engineering II Hokkaido University
Applied Mathematics I (co-taught)Applied Mathematics I (co-taught) Hokkaido University
Exercise in Computing (co-taught)Exercise in Computing (co-taught) Hokkaido University
Ductile Behavior of Steel Structures (Graduate)Ductile Behavior of Steel Structures (Graduate) University of Minnesota
Linear Structural AnalysisLinear Structural Analysis University of Minnesota
Steel Design IISteel Design II University of Minnesota

Association Memberships

• Japan Society of Seismic Isolation   American Society of Civil Engineers   American Institute of Steel Construction   JAPAN ASSOCIATION FOR EARTHQUAKE ENGINEERING   JAPANESE SOCIETY OF STEEL CONSTRUCTION   ARCHITECTURAL INSTITUTE OF JAPAN   

Research Projects

• Evaluation methodology and modular systems to enable steel reuse

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2024/06 -2028/03 

  Author : 岡崎 太一郎
• 鋼構造建築物の破壊過程の解明と倒壊余裕度の把握

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 2024/04 -2028/03 

  Author : 岡崎太一郎、松井良太、長江拓也
• High-Seismic-Performance Building with Sliding Foundation System and Reinforced Non-Structural Components

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Fund for the Promotion of Joint International Research (Fostering Joint International Research (B))

  Date (from‐to) : 2022/10 -2027/03 

  Author : 長江 拓也, 浅井 竜也, 柏 尚稔, 高橋 典之, 梶原 浩一, 藤原 淳, 岸田 明子, 松宮 智央, 岡崎 太一郎
• 環境負荷軽減を実現する座屈拘束ブレースの開発

  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
• Developing rational design metholodogy for chevron braced frames

  The Japan Iron and Steel Federation：Grants for Research and Education in Steel Structures

  Date (from‐to) : 2023/04 -2025/03 

  Author : 岡崎太一郎、松井良太、田川浩、陳星辰
• Numerical analysis of large deformation and stability response of steel structures under earthquake loading

  The Kajima Foundation：Researcher Exchange Support for International Researchers

  Date (from‐to) : 2024/04 -2024/06 

  Author : Ali IMANPOUR, Taichiro OKAZAKI
• Analysis and assessment technology for seismic collapse safety of steel building structures

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2020/04 -2024/03 

  Author : Taichiro OKAZAKI, Ryota MATSUI, Tomohiro MATSUMIYA, Noriyuki TAKAHASHI, Takuya NAGAE

   

  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。同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。大型耐震実験施設で、2021年12月に、縮尺1/3の4層ラーメン構造の倒壊実験を実施した。一方で、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てきた。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）倒壊実験によって、柱や梁が降伏し破断する過程と、損傷と破壊が架構全体に伝播する状況に関する実データを収録できた。（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てきた。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、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。
• Fracture of steel connections under very-low-cycle loading

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2022/09 -2023/09 

  Author : Taichiro OKAZAKI, WANG YUANZUO
• Development of a post-earthquake quick inspection method utilizing the movement data and video image of non-structural components in existing buildings subjected to a strong earthquake

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2020/04 -2023/03 

  Author : 長江 拓也, 梶原 浩一, 岡崎 太一郎, 松宮 智央, 高橋 典之, 藤原 淳, 岸田 明子

   

  本提案では，即時応急危険度判定として，地震被災建物の非構造材の動作に関する計測値分析と，屋内外のビデオ映像に基づく外観損傷や部材変形の画像解析を統合し，構造体の安全性はもとより建物機能の健全性を判定する方法を開発することを目標としている。さらに，判定結果を速やかに周囲に伝達することで，人間避難行動を適切に誘導する判定情報伝達技術の開発までを射程とする。本年度も引き続き，鋼構造架構を準備し，間仕切壁，カーテンウォールの加振実験を実施した。部材角を評価するGyro，表示のLEDの適用性について検証した。判定基準整備の一環として，確率論的性能評価の適用性について検討を重ねた。
• Proposal of Structural Design Method for Steel Structures Based on Ultimate Performance using Collapse Analysis

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2020/04 -2023/03 

  Author : 松井 良太, 岡崎 太一郎, 竹内 徹

   

  本研究課題では，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。2021年度では，鋼構造物の中でも，鋼材ブレースと合成梁の力学的性能を検証することに焦点を当てて研究計画を立てた。 第一に，2020年度に構築したデータベースを参照して製作した鋼材ブレースを対象とした模型載荷実験を実施した。試験体の断面には，H形鋼，円形鋼管，角形鋼管の3種を選定した。接合部には，境界条件の剛柔によるブレースの力学的性能の差異を確認すべく，端部のエンドプレートと溶接接合した形式と，ガセットプレートを介して接合した形式の2種を設定した。細長比を19から28とした太短いブレースを6体，比較のため51から65の比較的細長いブレースを4体用意した。H形鋼のフランジ幅厚比を6，円形鋼管の径厚比を31から39，角形鋼管の幅厚比を22から33となる断面を採用した。全試験体を繰返し載荷し，ブレースの耐力および塑性変形能力を検証した。本研究を計画した時点で予期していなかったブレースの破壊挙動を確認した。 次いで，鋼材の破壊力学の考え方を導入し，代表者が提案してきた繰返し載荷を受ける鋼材ブレースの塑性変形能力を評価する手法を発展させた。有限要素解析により，既往の載荷実験における角形鋼管ブレースの最大圧縮耐力，局部座屈による耐力劣化などの挙動について再現を試みた。他研究者が提案した破壊力学における鋼材の空隙進展モデルに適合する，鋼材ブレースの局部に集中した塑性歪を抽出するため，部材の要素分割，鋼材の材料特性などの条件を調整した。有限要素解析より得られた結果から，要素の歪をブレース軸方向にわたって抽出し，材全体の変形で局所に集中する塑性歪を評価するために必要となる事項を整理した。合成梁については，2020年度に実施した実験を参照し，コンクリート床スラブの有効幅の設定が性能に及ぼす影響を検討した。
• Demountable and reusable modular steel construction

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2020/11 -2023/03 

  Author : 岡崎 太一郎, ZONG LIANG
• Development of Modular Steel Construction to Promote Reclaiming and Reusing Structural Steel

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2019/11 -2022/03 

  Author : 岡崎 太一郎, XU FEI

   

  建築用鋼材は、建築物の供用期間が終了した時点でも、当初の性質をほとんど維持していると考えられるが、実際の建築物では、解体後に回収された鋼材はスクラップに回される。そこで本研究は、解体される建築物から採取した鋼部材を、新設建築物に再利用するための基礎技術を開発することを目的に掲げる。工学的な課題は、地震等によって塑性変形を受けた鋼材が、時間を経てその力学的特性を変える、ひずみ時効の影響である。2020年度は、代表的な鋼材について、塑性履歴とひずみ時効を受けたあと、力学的特性が変わる過程と要因を分析するための手法を開発した。試行的に、塑性変形と養生時間を経た鋼材において、微細構造が初期状態とどのように異なるかを調査した。微細構造分析には、後方散乱電子回折と透過電子顕微鏡、X線回析の組み合わせが有益であることを確認した。一方で、これまでに蓄積した実験データに基づいて、塑性変形とひずみ時効の影響を関数化して、鋼材の繰返し履歴則に組込む方法を整理した。有限要素法解析において、第一段階目の解析で生じた累積塑性ひずみに応じて、各要素の繰返し履歴則を分布的に更新したあと、第二段階目の解析を実施する方法を考案した。この有限要素法解析の有効性を、過去に実施した実験結果に対して検証した。結論として、過去の地震で塑性変形を受けた構造部材が、次に地震を受けたときにどのように違った挙動を示すかを、提案する解析法で適切に再現できることを示した。
• Rapid post-quake estimation of structural damage and performance based on modern ima ge processing technology

  Japan Society for the Promotion of Science：Bilateral Joint Research Project with National Natural Science Foundation of China

  Date (from‐to) : 2018/04 -2022/03
• Experimental study for MEMS sensor monitoring system to assess seismic response of Non-structural element of building

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2017/04 -2020/03 

  Author : Kajiwara Koichi

   

  In order to maintain and continue normal living and economic activities in our society, preparing for the future large-scale earthquake event, it is necessary to judge the performance of the infrastructures after the earthquake as a matter of course to improve the earthquake resistance before the earthquake. For this reason, many investigations have been conducted on structural health monitoring. Here, we have researched a system that estimates the structural characteristics of a building after the earthquake by capturing the response of non-structural element installed in the building with MEMS(micro-electro-mechanical systems) sensor. In this research, we have finished the basic investigation for practical use.
• Towards seismic design of steel buildings addressing collapse risk

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2017/04 -2020/03 

  Author : Taichiro OKAZAKI, Tomohiro MATSUMIYA, Noriyuki TAKAHASHI, Tetsuhiro ASARI, Takuya NAGAE

   

  The primary objective of the research was to obtain experimental data on failure of steel components and to advance the technology to numerically simulate the seismic response of steel building structures. The research was planned towards the larger goal of establishing a methodology to assess whether a steel building can safely survive, or maintain usable, after an extremely large earthquake beyond the consideration of building codes. Dynamic loading test of beam-to-column connections was conducted to examine how seismic performance may be affected by connection type and presence of composite floor slab. Numerical modeling techniques were examined to capture the gradual degradation of steel components due to start and propagation of ductile fracture. The model was used to demonstrate that good agreement can be obtained between simulated and experimental behavior of multi-story steel building systems. An additional study was conducted on damping models suited for nonlinear analysis.
• Comprehensive study on the 2018 Hokkaido Eastern Iburi Earthquake and its disaster

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2018/10 -2019/03 

  Author : Takahashi Hiroaki

   

  Comprehensive investigation on the 2018 Hokkaido Eastern Iburi earthquake and its disaster was conducted. Mainshock rupture initiated at deepest part and major slip was occurred in 20-30km deep. Multiple simultaneous landslides in Atsuma town was induced by combination of strong ground shaking and weak sliding layer between pyroclastic fall deposit layers. Halloysite cray minerals was discovered in all sliding layers. Simulation suggested landslides might attack residential houses within 6 seconds. Observed peak ground motions in nearby area were larger than common distance attenuation model. Severe wooden house damage in Mukawa town was due to amplified seismic waves due to site effects. Sounding and boring investigation revealed filled low-density volcanic ash and higher groundwater level in liquefaction area. Electricity blackout caused severe damage in social and economic activities of Hokkaido. These scientific outcomes were explained to residents at public briefing session.
• Substructure Shaking Table Test for Collapse Process of Reinforced Concrete Building

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2016/04 -2019/03 

  Author : Nagae Takuya, Yenidogan Cem, Takahashi Noriyuki, Matsumiya Tomohiro, Maruyama Ippei, Kajiwara Koichi, Mikoshiba Tadashi, Nakazawa Hiroshi

   

  A method of substructure test was developed by using a shaking table facility. Deformation time histories occurring in prototype buildings were applied to the substructure specimen equivalent to their critical portions. The force-deformation hysteresis was evaluated in the large deformation level significantly exceeding design limit, and compared with a promising numerical model, Krawinkler model. This model was developed in Stanford University, and is now recommended in the newest high-rise building design guideline of the United States. The ultimate energy capacity and other main parameters were tuned according to the test results. The numerical models, which represented substructure test results, were incorporated in the model of a full-scale frame test structure. The adopted method of static cyclic loading frame analysis indicated a new design procedure based on a reasonable performance assessment format.
• Evaluate collapse margin of medium-low-rise steel buildings

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2014/04 -2017/03 

  Author : MATSUMIYA Tomohiro

   

  For beam-to-column connection of the steel building, the gradual increase amplitude cyclic loading experiment which assumed loading speed (period 1Hz and 0.01Hz) were carried out. This experiment is fundamental researches for the performance evaluation technique construction that can evaluate the influence that the fracture property of the member end and the yield mechanism of the frame give to the ultimate state of the building. The conclusions obtained from this experiment are (1) The difference in loading speed produced differences of some behavior.(2) In the dynamic loading, beam-to-column connection fracture occur in comparison with static loading earlier, and plastic deformation capacity was inferior. For sliding in the high-strength bolt friction joint, the possibility that it hastened the crack spread started from the welding defect is thought about.
• Structural Performance and Seismic Design of Steel Building Structures without Base Anchorage

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2013/04 -2017/03 

  Author : NAKASHIMA, Masayoshi

   

  Japan and many regions in the world keep suffering from large earthquakes, and building collapse is considered to be most responsible for both the human and material losses. Advancement of building technologies for better collapse prevention is a critical societal need. This study proposes a new system in which the base of the super-structure is detached from the foundation, by which shear forces exerted onto the super-structure can be capped to a specified level. A series of dynamic loading test indicates that placing carbon graphite on the surface of foundation RC/mortar beam is found to ensure a friction coefficient of about 0.2 despite the number of sliding cycles. Theoretical equations are formulated to represent the sliding structure, and extensive time-history analyses are implemented for sliding structures subjected to pulse-type ground motions. The results verified that the maximum shear force applied to the super-structure is approximately twice the friction coefficient.
• Seismic Performance of Rocking Frames with Column Mid-height Uplift Mechanism at the First Story

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2013/04 -2016/03 

  Author : Midorikawa Mitsumasa, ASARI Tetsuhiro, AZUHATA Tatsuya, ISHIHARA Tadashi, OKAZAKI Taichiro

   

  The steel frames with column mid-height uplift (CMU) mechanism at the first story are implemented as response-control structural systems that reduce the seismic effects by exploiting the gravity effect generally deteriorating the seismic performance of ordinary structures. In the previous studies, the reduction effect on the seismic response of the column-base uplift (CBU) rocking systems with columns allowed to uplift has been evaluated and examined. The advantages and disadvantages of the systems have also been discussed. This study presents the seismic performance of CMU rocking frames with emphasis on the fundamental mechanical properties of CMU frames based on the simplified analytical models, performance evaluation of CMU mechanism resulted from the cyclically static loading tests and the seismic response behavior of CMU frames. Finally, some suggestions and recommendations are made on the seismic design of the rocking systems.
• Design and Seismic Performance of Steel Braced Frames

  The Japan Iron and Steel Federation：Grants for Research and Education in Steel Structures

  Date (from‐to) : 2014/04 -2016/03 

  Author : 岡崎太一郎
• Economic beam-to-column moment connections in steel structures

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2012/04 -2015/03 

  Author : OKAZAKI TAICHIRO

   

  Steel systems using I-shaped columns instead of box-shaped columns was examined to increase the economy of steel building construction. Two full-scale beam-to-column moment connections were tested in the laboratory. One specimen connected the beam to the column flange, while in the second specimen connected the beam to the column web. Both specimens exhibited similar performance to standard connections of a I-shaped beam to a box-shaped column. However, the connections to the web resulted in a 10% loss in stiffness. Out-of-plane deformation of the column web and in-plane deformation of the continuity plates was notable in the post-yield response. The experimental behavior was reproduced successfully by a detailed, nonlinear finite element simulation. Both the experiment and simulation indicated that the connection to the column web is susceptible to fracture in the weld between the beam flange and continuity plate.
• Development and Application oSfeismically Response-control

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2010 -2012 

  Author : MIDORIKAWA Mitsumasa, ASARI Tetsuhiro, AZUHATA Tatsuya, ISHIHARA Tadashi, OKAZAKI Taichiro

   

  The steel frames with uplift column-bases are implemented as response-control structural systems that reduce the seismic effects by exploiting the gravity effect generally deteriorating the seismic performance of ordinary structures. The reduction effect on the seismic response of the base-plate-yielding (BPY) rocking systems with columns allowed to uplift has been evaluated and examined. The advantages and disadvantages of the systems have also been discussed. This study presents the seismic response characteristics with emphasis on the torsional behavior of the BPY systems and proposes the advanced rocking systems resolving the disadvantage of the BPY systems towards developing and applying widely the rocking structural systems. Finally, some suggestions and recommendations are made on the seismic design of the rocking systems.
• Steel Connections using Structural Adhesives

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2010 -2011 

  Author : OKAZAKI Taichiro

   

  In order to examine how structural adhesives could be utilized in steel construction, a total of 65 double-splice tension coupons were constructed from two types of adhesives and with various splice proportions. With one of the adhesives, the coupon strength increased with splice length to the point where the splice strength exceeded the yield strength of steel. Three out of 50 specimens exhibited a 25% lower strength owing to the fact that they were governed by interfacial failure rather than cohesive failure. In contrast, with the other adhesive, the coupon strength did not change significantly with splice length and coupon failure was governed entirely by interfacial failure.
• International hybrid simulation of tomorrow's braced frame systems

  National Science Foundation：NEESR-SG

  Date (from‐to) : 2006 -2011 

  Author : Taichiro OKAZAKI
• Damage investigation and data collection for collapsed I-35WBridge

  National Science Foundation：SGER

  Date (from‐to) : 2007 -2009 

  Author : Taichiro OKAZAKI