鋼材の接着接合のせん断・引張と剥離に関する試験
高野春菜, 渡邊洋介, 岡崎太一郎
鋼構造論文集, 31, 123, 37, 47, 2024年10月, ［査読有り］, ［責任著者］
日本語, 研究論文（学術雑誌）, 31428767

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, American Society of Civil Engineers (ASCE), 2024年10月, ［査読有り］
英語, 研究論文（学術雑誌）

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, Elsevier BV, 2024年10月, ［査読有り］
英語, 研究論文（学術雑誌）, 11746794

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, Elsevier BV, 2024年07月, ［査読有り］
英語, 研究論文（学術雑誌）

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, Elsevier BV, 2024年05月, ［査読有り］
英語, 研究論文（学術雑誌）

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, Elsevier BV, 2024年03月, ［査読有り］
英語, 研究論文（学術雑誌）

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, Wiley, 2023年07月26日, ［査読有り］
英語, 研究論文（学術雑誌）, 31428741

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, Wiley, 2023年01月, ［査読有り］, ［責任著者］
英語, 研究論文（学術雑誌）

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, American Society of Civil Engineers (ASCE), 2023年01月, ［査読有り］, ［責任著者］
英語, 研究論文（学術雑誌）

大型輸入園芸用ハウスが有する構造性能の実験的検証
福家悠太, 岡崎太一郎, 松井良太
日本建築学会技術報告集, 28, 70, 1236, 1241, Architectural Institute of Japan, 2022年10月20日, ［査読有り］
日本語, 研究論文（学術雑誌）

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, American Society of Civil Engineers (ASCE), 2022年09月, ［査読有り］
英語, 研究論文（学術雑誌）

外壁パネル付大型ユニットハウスの耐震性能を検証する実験
松田 良介, 岡崎 太一郎, 長江 拓也, 松宮 智央, 高橋 典之, 神崎 喜和, 福井 隆浩, 飯嶋 俊比古, 桐山 義郎, 梶原 浩一
日本建築学会技術報告集, 28, 69, 679, 684, Architectural Institute of Japan, 2022年06月20日, ［査読有り］
日本語, 研究論文（学術雑誌）

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, American Society of Civil Engineers (ASCE), 2022年04月, ［査読有り］
英語, 研究論文（学術雑誌）, 11746795

ユニットハウスの耐震性能を検証する振動台実験
松田 良介, 岡崎 太一郎, 長江 拓也, 松宮 智央, 神崎 喜和, 福井 隆浩, 飯嶋 俊比古, 桐山 義郎, 梶原 浩一
日本建築学会技術報告集, 28, 68, 209, 214, Architectural Institute of Japan, 2022年02月20日, ［査読有り］
日本語, 研究論文（学術雑誌）

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, Elsevier BV, 2022年02月, ［査読有り］
英語, 研究論文（学術雑誌）, 11746794

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, Wiley, 2021年02月15日, ［査読有り］
英語, 研究論文（学術雑誌）, 31693108

粘性減衰モデルが弾塑性系の時刻歴応答解析に与える影響（その1）減衰モデルの比較
福富将, 岡崎太一郎, 松井良太, 麻里哲広
日本建築学会構造系論文集, 85, 778, 1555, 1563, Architectural Institute of Japan, 2020年12月, ［査読有り］, ［責任著者］
日本語, 研究論文（学術雑誌）, 11746794

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, American Society of Civil Engineers (ASCE), 2020年03月, ［査読有り］
英語, 研究論文（学術雑誌）

繰り返し変形に伴う合成梁の剛性劣化挙動に注目した数値解析
野々山優輔, 長江拓也, 岡崎太一郎, 松宮智央, 高橋典之, 梶原浩一, 中澤博志, 御子柴正
日本建築学会技術報告集, 26, 62, 153, 158, 2020年02月, ［査読有り］
日本語, 研究論文（学術雑誌）, 11746794

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, 2018年09月, ［査読有り］
英語, 研究論文（学術雑誌）, 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.

一面せん断接合部を有する鋼管ブレースの座屈耐力に与えるガセットプレートの面外曲げ剛性および耐力の影響
浅田勇人, 岡崎太一郎, 田中剛, 中井沙耶, 橋岡昇吾
日本建築学会構造論文集, 83, 744, 309, 319, 2018年02月, ［査読有り］
日本語, 研究論文（学術雑誌）, © 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, American Society of Civil Engineers (ASCE), 2017年12月01日, ［査読有り］
英語, 研究論文（学術雑誌）, 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, ELSEVIER SCI LTD, 2017年11月, ［査読有り］
英語, 研究論文（学術雑誌）, 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, ASCE-AMER SOC CIVIL ENGINEERS, 2017年02月, ［査読有り］
英語, 研究論文（学術雑誌）, 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, ASCE-AMER SOC CIVIL ENGINEERS, 2017年02月, ［査読有り］
英語, 研究論文（学術雑誌）, 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, ASCE-AMER SOC CIVIL ENGINEERS, 2016年02月, ［査読有り］
英語, 研究論文（学術雑誌）, 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, ASCE-AMER SOC CIVIL ENGINEERS, 2016年02月, ［査読有り］
英語, 研究論文（学術雑誌）, 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, ASCE-AMER SOC CIVIL ENGINEERS, 2016年02月, ［査読有り］
英語, 研究論文（学術雑誌）, 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年02月, ［査読有り］
英語, 研究論文（学術雑誌）

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, ASCE-AMER SOC CIVIL ENGINEERS, 2015年08月, ［査読有り］, ［筆頭著者, 責任著者］
英語, 研究論文（学術雑誌）, 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, ASCE-AMER SOC CIVIL ENGINEERS, 2015年08月, ［査読有り］
英語, 研究論文（学術雑誌）, 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, ELSEVIER SCI LTD, 2014年10月, ［査読有り］
英語, 研究論文（学術雑誌）, 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.

H‐SA700 鋼と高力ボルトを用いた組立柱の柱梁接合部
林和宏, 岡崎太一郎, 林旭川, 中島正愛
鋼構造論文集、日本鋼構造協会, 21, 82, 39, 50, 2014年06月, ［査読有り］
日本語, 研究論文（学術雑誌）

Stability of beams in steel eccentrically braced frames
Gul Yigitsoy, Cem Topkaya, Taichiro Okazaki
JOURNAL OF CONSTRUCTIONAL STEEL RESEARCH, 96, 14, 25, ELSEVIER SCI LTD, 2014年05月, ［査読有り］
英語, 研究論文（学術雑誌）, 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.

上部構造の鉛直剛性を考慮した構造物の基礎浮き上がり地震応答
麻里哲弘, 氏家大介, 緑川光正, 岡崎太一郎
日本建築学会構造論文集, 79, 705, 1569, 1578, Architectural Institute of Japan, 2014年, ［査読有り］
日本語, 研究論文（学術雑誌）, 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, ASCE-AMER SOC CIVIL ENGINEERS, 2013年11月, ［査読有り］, ［責任著者］
英語, 研究論文（学術雑誌）, 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, ASCE-AMER SOC CIVIL ENGINEERS, 2013年08月, ［査読有り］
英語, 研究論文（学術雑誌）, 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, 2013年04月01日, ［査読有り］, ［筆頭著者, 責任著者］
英語, 研究論文（学術雑誌）, 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.

超高層鋼構造建物の現場溶接接合部が有する耐震性能を検証するE-ディフェンス振動台実験
岡崎太一郎, 松宮智央, 長江拓也, 福山國夫, 井上貴仁, 中島正愛
日本建築学会構造論文集, 78, 685, 569, 578, 2013年03月, ［査読有り］, ［筆頭著者, 責任著者］
日本語, 研究論文（学術雑誌）, 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, EARTHQUAKE ENGINEERING RESEARCH INST, 2013年03月, ［査読有り］, ［筆頭著者, 責任著者］
英語, 研究論文（学術雑誌）, 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, ELSEVIER SCI LTD, 2013年03月, ［査読有り］
英語, 研究論文（学術雑誌）, 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年12月, ［査読有り］
日本語, 研究論文（学術雑誌）

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, KOREAN SOC STEEL CONSTRUCTION-KSSC, 2012年09月, ［査読有り］
英語, 研究論文（学術雑誌）, 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, ASCE-AMER SOC CIVIL ENGINEERS, 2012年07月, ［査読有り］
英語, 研究論文（学術雑誌）, 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, ELSEVIER SCI LTD, 2012年02月, ［査読有り］
英語, 研究論文（学術雑誌）, 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.

超高層鋼構造建物の柱梁接合部に関する４層骨組振動台実験
松宮智央, 長江拓也, CHUNG Yu‐Lin, 岡崎太一郎, 福山國夫, 中島正愛
日本建築学会構造系論文集, 77, 676, 975, 984, 2012年, ［査読有り］
英語, 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, SAGE PUBLICATIONS LTD, 2011年01月, ［査読有り］
英語, 研究論文（学術雑誌）, 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, ASCE-AMER SOC CIVIL ENGINEERS, 2011年01月, ［査読有り］
英語, 研究論文（学術雑誌）, 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, ASCE-AMER SOC CIVIL ENGINEERS, 2010年05月, ［査読有り］
英語, 研究論文（学術雑誌）, 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, ELSEVIER SCI LTD, 2009年08月, ［査読有り］, ［筆頭著者, 責任著者］
英語, 研究論文（学術雑誌）, 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, ELSEVIER SCI LTD, 2009年07月, ［査読有り］, ［筆頭著者, 責任著者］
英語, 研究論文（学術雑誌）, 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, ELSEVIER SCI LTD, 2007年06月, ［査読有り］, ［筆頭著者, 責任著者］
英語, 研究論文（学術雑誌）, 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, JOHN WILEY & SONS LTD, 2007年01月, ［査読有り］, ［筆頭著者, 責任著者］
英語, 研究論文（学術雑誌）, 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, AMER INST STEEL CONSTRUCTION, 2007年, ［査読有り］
英語, 研究論文（学術雑誌）

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, ASCE-AMER SOC CIVIL ENGINEERS, 2006年09月, ［査読有り］, ［筆頭著者, 責任著者］
英語, 研究論文（学術雑誌）, 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 (vol 132, pg 1201, 2006)
Taichiro Okazaki, Michael D. Engelhardt, Masayoshi Nakashima, Keiichiro Suita
JOURNAL OF STRUCTURAL ENGINEERING-ASCE, 132, 8, 1201, 1211, ASCE-AMER SOC CIVIL ENGINEERS, 2006年08月, ［査読有り］, ［筆頭著者, 責任著者］
英語, 研究論文（学術雑誌）, 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, ASCE-AMER SOC CIVIL ENGINEERS, 2005年10月, ［査読有り］, ［筆頭著者, 責任著者］
英語, 研究論文（学術雑誌）, 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年03月, ［査読有り］
日本語, 研究論文（学術雑誌）

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年03月, ［査読有り］
日本語, 研究論文（学術雑誌）

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年12月, ［査読有り］
英語, 研究論文（学術雑誌）

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, PERGAMON-ELSEVIER SCIENCE LTD, 1996年10月, ［査読有り］
英語, 研究論文（学術雑誌）, 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.

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年07月, ［査読有り］
英語, 研究発表ペーパー・要旨（国際会議）

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年07月, ［査読有り］, ［責任著者］
英語, 研究発表ペーパー・要旨（国際会議）, 31428741

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年07月, ［査読有り］
英語, 研究発表ペーパー・要旨（国際会議）

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年07月, ［査読有り］
英語, 研究発表ペーパー・要旨（国際会議）, 31428741

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年07月, ［査読有り］
英語, 研究発表ペーパー・要旨（国際会議）, 31428741

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年07月, ［査読有り］
英語, 研究発表ペーパー・要旨（国際会議）

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年07月, ［査読有り］
英語, 研究発表ペーパー・要旨（国際会議）, 31428741

色褪せない実験的研究の意義　　　　　　　　　　　　　　　
岡崎太一郎, Structure、JSCA, 171, 36, 37, 2024年07月, ［招待有り］, ［筆頭著者］
日本語, 記事・総説・解説・論説等（その他）

塑性変形とひずみ時効を経た鋼梁の残存耐震性能と形状不整　　　　　　　　　　　　　　　
中川春香, 新井文佳, ヤン シャオキ, 岡崎太一郎, 鋼構造年次論文報告集、日本鋼構造協会, 30, 497, 506, 2022年12月, ［査読有り］
日本語, 研究発表ペーパー・要旨（全国大会，その他学術会議）

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年09月
日本語, 講演資料等（セミナー，チュートリアル，講習，講義他）

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年05月, ［査読有り］
Springer International Publishing, 英語, 会議報告等

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年05月, ［査読有り］
Springer International Publishing, 英語, 会議報告等, 31428741

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年05月, ［査読有り］
Springer International Publishing, 英語, 会議報告等, 31428741

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年05月, ［査読有り］
Springer International Publishing, 英語, 会議報告等

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年05月, ［査読有り］
Springer International Publishing, 英語, 会議報告等

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年04月
英語, 記事・総説・解説・論説等（学術雑誌）

画像処理とモニタリングを用いた間仕切壁のフラジリティ評価に関する基礎的検討
梅林舞, 高橋典之, 千田紘之, 長江拓也, 岡崎太一郎, 松宮智央, 梶原浩一, 中澤博志, 神崎喜和, Journal of Structural Engineering B, 68B, 261, 270, 2022年04月, ［査読有り］
Architectural Institute of Japan, 日本語, 会議報告等, 31428741

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年01月, ［招待有り］
日本語, 記事・総説・解説・論説等（学術雑誌）

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年10月, ［招待有り］
日本語, 記事・総説・解説・論説等（商業誌、新聞、ウェブメディア）

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年09月
英語, 研究発表ペーパー・要旨（国際会議）

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年09月
英語, 研究発表ペーパー・要旨（国際会議）

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年09月, ［筆頭著者］
研究発表ペーパー・要旨（国際会議）

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年09月
日本語, 講演資料等（セミナー，チュートリアル，講習，講義他）

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年09月
日本語, 講演資料等（セミナー，チュートリアル，講習，講義他）

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年12月
英語, 研究発表ペーパー・要旨（国際会議）

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年12月
英語, 研究発表ペーパー・要旨（国際会議）

H形断面ブレースを用いたK形ブレース付鋼架構の繰返し載荷実験
上杉周平, 関あきり, 岡崎太一郎, 浅田勇人, 鋼構造年次論文報告集、日本鋼構造協会, 26, 196, 203, 2018年11月
日本語, 11746797

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年09月
日本語, 講演資料等（セミナー，チュートリアル，講習，講義他）

Cyclic loading behavior of steel chevron braced frames　　　　　　　　　　　　　　　
Taichiro Okazaki, Hayato Asada, Mitsumasa Midorikawa, Tetsuhiro Asari, 16th World Conference on Earthquake Engineering (16WCEE), Paper No. 11271, 2018年06月, ［筆頭著者］
英語, 研究発表ペーパー・要旨（国際会議）

Now Available: English Translation of the 2005 AIJ Design Standard for Steel Structures　　　　　　　　　　　　　　　
岡崎太一郎, Steel Construction Today & Tomorrow, 52, 3, 4, 2017年12月
英語, 記事・総説・解説・論説等（その他）

構造用接着剤を用いた鋼梁継手の曲げせん断実験 その2　　　　　　　　　　　　　　　
渡邊洋介, 高野春菜, 岡崎太一郎, 堀井久一, 麻里哲広, 鋼構造年次論文報告集、日本鋼構造協会, 25, 602, 609, 2017年11月, ［査読有り］
日本語, 研究発表ペーパー・要旨（全国大会，その他学術会議）

鋼材の接着接合部の基本特性に関する実験的研究　　　　　　　　　　　　　　　
高野春菜, 渡邊洋介, 岡崎太一郎, 岡田忠義, 寺田慎平, 鋼構造年次論文報告集、日本鋼構造協会, 25, 594, 601, 2017年11月, ［査読有り］
日本語, 研究発表ペーパー・要旨（全国大会，その他学術会議）

K形ブレース付鋼架構の繰返し載荷実験　　　　　　　　　　　　　　　
関あきり, 上杉周平, 岡崎太一郎, 浅田勇人, 麻里哲広, 鋼構造年次論文報告集、日本鋼構造協会, 25, 841, 848, 2017年11月, ［査読有り］
日本語, 研究発表ペーパー・要旨（全国大会，その他学術会議）

基礎浮き上がり構造物の地震応答：有限回転角‐弾性系による考察　　　　　　　　　　　　　　　
中田和志, 麻里哲広, 岡崎太一郎, 緑川光正, 構造工学論文報告集、日本建築学会, 63B, 351, 358, 2017年04月, ［査読有り］
日本語, 研究発表ペーパー・要旨（全国大会，その他学術会議）

座屈拘束ブレースの破壊モードと圧縮耐力上昇、エネルギー消費率　　　　　　　　　　　　　　　
大内京太郎, 山崎翔, 緑川光正, 岩田衛, 岡崎太一郎, 麻里哲広, 構造工学論文報告集、日本建築学会, 63B, 543, 552, 2017年04月, ［査読有り］
日本語, 研究発表ペーパー・要旨（全国大会，その他学術会議）

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年01月
英語, 記事・総説・解説・論説等（国際会議プロシーディングズ）

耐震診断結果に基づく北海道の建築物の耐震性能と地震被害予測
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年03月
北海道地区自然災害科学資料センター (北海道大学大学院工学研究院), 日本語

構造用接着剤を用いた鋼梁継手の曲げせん断実験　　　　　　　　　　　　　　　
井上桂輔, 岡崎太一郎, 緑川光正, 麻里哲広, 堀井久一, 鋼構造年次論文報告集、日本鋼構造協会, 23, 262, 269, 2015年11月, ［査読有り］
日本語, 研究発表ペーパー・要旨（全国大会，その他学術会議）

013 北海道のブレース付鋼架構の設計に関するアンケート調査(構造II,講演研究論文、計画・技術報告)
岡崎 太一郎, 緑川 光正, 麻里 哲広, 日本建築学会北海道支部研究報告集, 88, 55, 60, 2015年06月27日
一般社団法人日本建築学会, 日本語

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年
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., Earthquake Engineering Research Institute, 英語, 記事・総説・解説・論説等（国際会議プロシーディングズ）

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年
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., Earthquake Engineering Research Institute, 英語, 記事・総説・解説・論説等（国際会議プロシーディングズ）

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年
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., Earthquake Engineering Research Institute, 英語, 記事・総説・解説・論説等（国際会議プロシーディングズ）

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年01月
日本語, 記事・総説・解説・論説等（その他）

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年11月01日
建築技術, 日本語

Japanese research on super-high-strength structural steel　　　　　　　　　　　　　　　
Taichiro Okazaki, Fukami Hidenori, Masato Ohata, Masayoshi Nakashima, North American Steel Construction Conference (NASCC), 2012年04月, ［招待有り］
英語, 記事・総説・解説・論説等（国際会議プロシーディングズ）

2011年3月11日東北地方太平洋沖地震 建築物被害調査報告
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年03月
北海道大学大学院工学研究科北海道地区自然災害科学資料センター, 日本語

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年02月20日
社団法人日本建築学会, 日本語

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年, ［査読有り］
英語

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年07月, ［査読有り］
英語, 研究発表ペーパー・要旨（国際会議）

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年05月
英語, 研究発表ペーパー・要旨（国際会議）

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年11月01日
日本語

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年09月
日本語, 記事・総説・解説・論説等（学術雑誌）

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年08月, ［査読有り］
英語, 研究発表ペーパー・要旨（国際会議）

22349 偏心ブレース構造におけるリンク材の履歴挙動(梁材(1),構造III)
岡崎 太一郎, エンゲルハート マイケル, 学術講演梗概集. C-1, 構造III, 木質構造, 鉄骨構造, 鉄骨鉄筋コンクリート構造, 2005, 0, 697, 698, 2005年07月31日
社団法人日本建築学会, 日本語

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年08月
英語, 研究発表ペーパー・要旨（全国大会，その他学術会議）

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年08月, ［査読有り］, ［筆頭著者］
英語, 研究発表ペーパー・要旨（国際会議）

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年08月, ［査読有り］, ［筆頭著者］
英語, 研究発表ペーパー・要旨（国際会議）

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年06月, ［査読有り］, ［筆頭著者］
英語, 研究発表ペーパー・要旨（国際会議）

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年06月, ［査読有り］
英語, 研究発表ペーパー・要旨（国際会議）

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年07月

22409 繰り返し軸方向載荷を受ける薄肉開断面部材の弾塑性挙動
岡崎 太一郎, 野中 泰二郎, 学術講演梗概集. C-1, 構造III, 木質構造, 鉄骨構造, 鉄骨鉄筋コンクリート構造, 1996, 0, 817, 818, 1996年07月30日
社団法人日本建築学会, 日本語

2055 繰り返し軸方向載荷を受ける薄肉開断面部材の弾塑性挙動(構造)
岡崎 太一郎, 野中 泰二郎, 日本建築学会近畿支部研究報告集. 構造系, 0, 36, 233, 236, 1996年07月03日
社団法人日本建築学会, 日本語

日本建築学会：鋼構造許容応力度設計規準　　　　　　　　　　　　　　　
岡崎太一郎, 1章から6章
丸善出版, 2019年10月, ［共著］

AIJ Design Standard for Steel Structures ― Based on Allowable Stress Concept― (2005 Edition)　　　　　　　　　　　　　　　
岡崎太一郎, 1章から4章
Architectural Institute of Japan, 2017年10月, ［共訳］

日本建築学会：鋼構造塑性設計指針（第4版）　　　　　　　　　　　　　　　
岡崎太一郎, 7章
丸善出版, 2017年02月, ［共著］

日本建築学会：鋼構造環境配慮設計指針（案）―部材リユース―　　　　　　　　　　　　　　　
岡崎太一郎, 2.2節、4.1節
丸善出版, 2015年12月, ［共著］

JSSC Sets of Torshear Type High-Strength Bolt, Hexagon Nut and Plain Washer for structural Joints (English translation)　　　　　　　　　　　　　　　
岡崎太一郎, 全体
日本鋼構造協会, ［共著］

Seismic Performance of Steel Beam-to-Column Moment Connections in Japan　　　　　　　　　　　　　　　
Taichiro Okazaki
Tianjin University / National Facility for Earthquake Engineering Simulation, 2020年11月16日, 英語, 公開講演，セミナー，チュートリアル，講習，講義等
［招待講演］

地震と鋼材―阪神・淡路大地震から25年を過ぎて―　　　　　　　　　　　　　　　
岡崎太一郎
第71回白石記念講座, 2019年11月28日, 日本語, 公開講演，セミナー，チュートリアル，講習，講義等
［招待講演］, ［国内会議］

Contribution of Academic Research to the Seismic Safety of Steel Structures in Japan.　　　　　　　　　　　　　　　
岡崎太一郎
16th Symposium on Earthquake Engineering (India), 2018年12月22日, 英語, 口頭発表（基調）
［招待講演］, ［国際会議］

Seismic Design Procedure of Steel Structures in Japan: Past, Present, and Future　　　　　　　　　　　　　　　
岡崎太一郎
名古屋工業大学 国際シンポジウム (2018 年度), 2018年09月10日, 英語, 口頭発表（招待・特別）
［招待講演］, ［国際会議］

Japanese Research on Super-High-Strength Structural Steel　　　　　　　　　　　　　　　
Taichiro OKAZAKI, Hidenori FUKAMI, Masato OHATA, Masayoshi NAKASHIMA
NASCC: The Steel Conference, 2012年04月20日, 英語, 口頭発表（一般）
［招待講演］, ［国際会議］

SDGs演習：課題解決に向けた国際共修PBL　　　　　　　　　　　　　　　
北海道大学
2022年06月 - 現在

各種構造Ⅱ　　　　　　　　　　　　　　　
北海道大学
2020年04月 - 現在

建築材料演習（分担）　　　　　　　　　　　　　　　
北海道大学
2018年04月 - 現在

建築構造解析特論　　　　　　　　　　　　　　　
北海道大学
2018年04月 - 現在

建築鋼構造特論　　　　　　　　　　　　　　　
北海道大学
2017年04月 - 現在

構造力学Ⅱ　　　　　　　　　　　　　　　
北海道大学
2016年10月 - 現在

構造力学Ⅰ　　　　　　　　　　　　　　　
北海道大学
2016年04月 - 現在

建築序説（分担）　　　　　　　　　　　　　　　
北海道大学
2012年04月 - 現在

工学的創生実験Ⅳ：材料と力から構造物を考える（分担）　　　　　　　　　　　　　　　
北海道大学
2019年12月 - 2021年03月

構造力学Ⅲ　　　　　　　　　　　　　　　
北海道大学
2012年10月 - 2019年08月

構造解析１　　　　　　　　　　　　　　　
北海道大学
2011年10月 - 2018年01月

建築算法　　　　　　　　　　　　　　　
北海道大学
2011年10月 - 2018年01月

建築振動工学特論（旧：動力学系特論）　　　　　　　　　　　　　　　
北海道大学
2011年10月 - 2017年08月

建築都市ゼミナール２（分担）　　　　　　　　　　　　　　　
北海道大学
2011年03月 - 2016年08月

応用数学１（分担）　　　　　　　　　　　　　　　
北海道大学
2011年04月 - 2013年08月

コンピューティング演習（分担）　　　　　　　　　　　　　　　
北海道大学
2011年04月 - 2013年08月

鋼構造の挙動と設計　　　　　　　　　　　　　　　
米国ミネソタ州立大学
2007年02月 - 2009年05月

構造力学　　　　　　　　　　　　　　　
米国ミネソタ州立大学
2005年09月 - 2008年12月

鋼構造の設計Ⅱ　　　　　　　　　　　　　　　
米国ミネソタ州立大学
2006年02月 - 2008年05月

鋼材リユースを可能にする評価技術と構造システムの開発
科学研究費助成事業
2024年06月 - 2028年03月
岡崎 太一郎
日本学術振興会, 挑戦的研究(開拓), 北海道大学, 研究代表者, 24K21220

鋼構造建築物の破壊過程の解明と倒壊余裕度の把握
科学研究費助成事業
2024年04月 - 2028年03月
岡崎太一郎、松井良太、長江拓也
日本学術振興会, 基盤研究(A), 北海道大学, 24H00340

基礎滑り構造と二次部材耐震対策の導入による建築物の高耐震化
科学研究費助成事業 国際共同研究加速基金(国際共同研究強化(B))
2022年10月07日 - 2027年03月31日
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
日本学術振興会, 国際共同研究加速基金(国際共同研究強化(B)), 名古屋大学, 22KK0063

環境負荷軽減を実現する座屈拘束ブレースの開発
科学研究費助成事業
2023年06月30日 - 2026年03月31日
松井 良太, 岡崎 太一郎, 丸山 一平
日本学術振興会, 挑戦的研究(萌芽), 北海道大学, 23K17781

Ｋ形ブレース構造とＫ形偏心ブレース構造の合理的な設計　　　　　　　　　　　　　　　
鋼構造研究・教育助成事業
2023年04月 - 2025年03月
岡崎太一郎、松井良太、田川浩、陳星辰
日本鉄鋼連盟, 研究分野指定助成, 研究代表者

地震による鋼構造建築物の大変形挙動や不安定挙動を再現する数値 解析技術　　　　　　　　　　　　　　　
外国人研究者（受入れ）
2024年04月 - 2024年06月
Ali IMANPOUR, 岡崎太一郎
鹿島学術振興財団

鋼構造建築物の倒壊挙動に対する予測技術と性能評価技術の高度化
科学研究費助成事業
2020年04月 - 2024年03月
岡崎 太一郎, 松井 良太, 松宮 智央, 高橋 典之, 長江 拓也
鋼構造建築物の倒壊過程を実験的に解明する研究目的に沿って、国立研究開発法人防災科学技術研究所の大型耐震実験施設で、2020年11月から12月にかけて、縮尺1/2のパイロット試験体による振動台実験を実施した。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。
日本学術振興会, 基盤研究(A), 北海道大学, 20H00269

極低サイクル載荷で破断に至る鋼構造接合部の挙動の解明　　　　　　　　　　　　　　　
科学研究費助成事業
2022年09月 - 2023年09月
岡崎 太一郎, WANG YUANZUO
日本学術振興会, 特別研究員奨励費, 北海道大学, 22F22042

地震被災建物の非構造材の動作計測と画像解析に基づく即時応急危険度判定技術の構築
科学研究費助成事業
2020年04月01日 - 2023年03月31日
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。
日本学術振興会, 挑戦的研究(開拓), 名古屋大学, 20K20435

崩壊解析による鋼構造物の限界性能評価に基づく構造設計法の確立
科学研究費助成事業
2020年04月01日 - 2023年03月31日
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。
日本学術振興会, 基盤研究(B), 北海道大学, 20H02292

解体可能・再利用可能な建築物を構築するモジュール工法
科学研究費助成事業 特別研究員奨励費
2020年11月 - 2023年03月
岡崎 太一郎, ZONG LIANG
日本学術振興会, 特別研究員奨励費, 北海道大学, 20F20354

構造部材の再利用を可能にする鋼構造建築物のモジュール化技術
科学研究費助成事業 特別研究員奨励費
2019年11月 - 2022年03月
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。
日本学術振興会, 特別研究員奨励費, 北海道大学, 19F19360

画像処理技術を応用した地震被災建物の応急危険度判定技術の開発
二国間交流事業 中国(NSFC)との共同研究
2018年04月 - 2022年03月
JSPS 日本学術振興会(JSPS), 北海道大学, 研究代表者

外装材挙動を利用する損傷モニタリングのためのＭＥＭＳ技術開発と振動台実験
科学研究費助成事業
2017年04月01日 - 2020年03月31日
梶原 浩一, 榎田 竜太, 岡崎 太一郎, 長江 拓也, 高橋 典之, 松宮 智央
将来の大規模地震が発生した際に、普段の生活と経済活動を維持・継続するためには、インフラ構造物の耐震性能の向上に加えて、地震を受けたインフラ建物が速やかに使用できるか否かを判別する必要がある。このために構造ヘルスモニタリングの研究が盛んに進められている。ここでは、建物に具備される外装材の応答をMEMS(micro-electro-mechanical systems)センサで捉え、建物全体の損傷等を推定するモニタリング手法の有効性を検証できた。
日本学術振興会, 基盤研究(C), 国立研究開発法人防災科学技術研究所, 17K06666

倒壊にいたるまでの性能を考慮した鋼構造建築物の耐震設計法の確立
科学研究費助成事業
2017年04月 - 2020年03月
岡崎 太一郎, 松宮 智央, 高橋 典之, 麻里 哲広, 長江 拓也
本研究は、鋼構造建築物の倒壊挙動を再現する振動台実験を実施し、部材破壊から応力再分配、振動特性の変化、変形の増大と集中を経て、倒壊にいたる過程を解明する。実験で観察した挙動を精度よく追跡できるコンピュータ解析技術を蓄積する。さらに、鋼構造建築物の耐震性能余裕度を定量化し、それを織り込んだ設計法を開発することを目的とする。
第2年度は、初年度に引きつづき、柱梁接合部の動的載荷実験を実施した。柱と梁で構成され、鉄筋コンクリート床スラブを付けたト形試験体を2体製作し、それぞれに現場溶接式と工場溶接式の接合部を採用した。接合部形式による性能の違いと、昨年度実験した試験体と合わせて、スラブが接合部性能に及ぼす影響を検証した。この実験データを基に、それぞれの接合部詳細の特徴を反映した数値モデルを構築し、接合部詳細の違いが鋼構造物の耐震性能の違いに及ぼす影響を解析によって検討した。また、動画撮影で得た画像をもとに、デジタル画像相関法による歪分布の測定を試みた。
破断による構造要素の耐力と剛性の劣化、それに伴う応力再分配を追跡できる数値解析を、ある程度まで実現した。部材実験に対して較正した数値モデルを、二次元骨組モデルに組み込み、過去に実施された大型振動台実験の応答を、ある程度の精度で再現することができた。
目指す詳細な動的応答解析を達成するためには、構造要素の弾塑性性状を精密にモデルするだけでなく、剛性と振動特性の変化に追従できる減衰モデルの開発が欠かせない。そこで、既存の減衰モデルに関して、広範な文献調査を実施し、また代表的な減衰モデルを簡易な構造モデルに適用して、減衰モデルが非線形応答に及ぼす影響を検証した。
日本学術振興会, 基盤研究(B), 北海道大学, 17H03336

平成30年北海道胆振東部地震とその災害に関する総合調査
科学研究費助成事業
2018年10月04日 - 2019年03月31日
高橋 浩晃, 勝俣 啓, 大園 真子, 橋本 武志, 青山 裕, 酒井 慎一, 松本 聡, 岡田 知己, 小菅 正裕, 寺川 寿子, 飯尾 能久, 中尾 茂, 上嶋 誠, 柴田 智郎, 大津 直, 高井 伸雄, 飯場 正紀, 渡部 要一, 菊地 優, 岡崎 太一郎, 白井 和貴, 西村 裕一, 石川 達也, 高瀬 裕也, 永井 宏, 宮森 保紀, 三宅 弘恵, 松島 信一, 浅野 公之, 重藤 迪子, 卜部 厚志, 前田 宜浩, 石澤 友浩, 廣瀬 亘, 小山内 信智, 山田 孝, 笠井 美青, 檜垣 大助, 風間 基樹, 千木良 雅弘, 渦岡 良介, 竹林 洋史, 木村 誇, 石丸 聡, 岡田 成幸, 内田 賢悦, 有村 幹治, 植松 武是, 多々納 裕一, 梶谷 義雄, 能島 暢呂, 田村 圭子, 中村 洋光, 戸松 誠
平成３０年北海道胆振東部地震とその災害に関する総合調査を実施した。大きな人的被害を出した厚真町の同時多発斜面崩壊では、周辺火山の噴火により厚く堆積した火砕降下物の底面に粘土化したすべり面が確認された。震源近くでは距離減衰式より大きな速度加速度が観測され、むかわ町の建物被害は地盤構造による地震動の増幅が影響しいる可能性が示された。札幌市内の住宅地で発生した液状化は、密度の小さな火山灰での谷埋め盛土と高い地下水位が関与している可能性が示された。道内全域停電が社会インフラや社会経済活動に与えた実態が明らかにされた。住民も対象とした成果報告会を開催し研究成果の社会還元を行った。
日本学術振興会, 特別研究促進費, 北海道大学, 18K19952

コンクリート系建物の骨組崩壊過程把握のためのサブストラクチャ振動台実験
科学研究費助成事業
2016年04月01日 - 2019年03月31日
長江 拓也, 岡崎 太一郎, 高橋 典之, 松宮 智央, 丸山 一平, 梶原 浩一, 御子柴 正, 中澤 博志
建物骨組を部分的に切り出す実験手法に基づき，骨組の超大変形時の弾塑性挙動に関する実験資料を蓄積した。数値解析に向けて，実験結果と対比しつつ，崩壊評価に必要となる数値解析モデルの主要パラメータを特定した。検証後の数値解析モデルを全体骨組に組み込み，地震動種類，地震動強さを多岐に変化させる地震応答解析を通して，全体骨組の崩壊挙動を評価する確率論的手法を例示した。実務への適用性を高める手法として，全体骨組に対して，その振動モード形状を外力分布形状に採用し，固定する条件において，等価高さ位置における変位履歴を地震応答を参照して制御する静的繰り返し載荷解析を提案した。
日本学術振興会, 基盤研究(C), 名古屋大学, 16K06568

中低層鉄骨造建物の崩壊余裕度と評価手法に関する基礎研究
科学研究費助成事業
2014年04月01日 - 2017年03月31日
松宮 智央, 岡崎 太一郎, 長江 拓也, 高橋 典之
部材端部の破断性状と骨組の降伏機構が建物の終局限界に及ぼす影響を評価できる性能評価手法構築のための基礎研究として，同一の鉄骨造の柱梁接合部試験体に対して，載荷速度（周期1 Hzと0.01 Hz）を因子とした漸増振幅繰返し載荷実験を実施した。本実験から得られた知見を以下に示す。
(1)載荷速度の違いは，材料強度に影響するほどのひずみ速度の違いをもたらさなかったにも関わらず，多少の挙動の差を生み出した。
(2)動的載荷では，静的載荷と比較してより早期に破断し，塑性変形能力が劣った。高力ボルト摩擦接合における滑りなどが原因で，急速な負荷が溶接欠陥を起点とした亀裂伝播を早めた可能性が考えられる。
日本学術振興会, 基盤研究(C), 近畿大学, 26420570

直置き型鋼構造建築物の構造性能と耐震設計
科学研究費助成事業
2013年04月01日 - 2017年03月31日
中島 正愛, 岡崎 太一郎, 松宮 智央, 保木 和明, 倉田 真宏
より高度な耐震構造を構築すべく、本研究では、上部構造と基礎部を緊結させず、大地震に対してはこの界面で滑らせることによって、上部構造に作用する最大せん断力を制御する「直置き型構造物」を提案した。黒鉛潤滑剤を界面に撒くという簡便かつ安価な方法によって、滑り係数として約0.2を確保することができ、また多数回の滑りに対しても安定した滑り係数が保持されることを、一連の振動台実験から明らかにした。また滑りを伴う2自由度系への理論展開と網羅的な時刻歴応答解析から、パルス性の高い地震動に対して上部構造に作用する最大せん断力係数として、滑り係数の2倍が目安になることを導いた。
日本学術振興会, 基盤研究(A), 京都大学, 25249078

柱中間部浮き上がり機構を有するロッキング架構の耐震性能
科学研究費助成事業
2013年04月01日 - 2016年03月31日
緑川 光正, 麻里 哲広, 小豆畑 達也, 石原 直, 岡崎 太一郎
鉛直荷重は建築構造物の耐震性能を損なうものと一般に考えられている。柱中間部浮き上がり(CMU)機構を有するロッキング架構は，鉛直荷重を活用して地震応答低減を図る構造システムである。先行研究では，浮き上がりに伴って容易に降伏するベースプレートを柱脚部に設置したロッキング架構の地震応答低減効果や地震時挙動を明らかにした。本研究では，今までの研究成果に基づき，CMU機構を有するロッキング架構(CMU架構)の耐震性能を明らかにすることを目的として，簡易解析モデルによるCMU架構の基本力学特性，CMU機構(荷重伝達+エネルギー吸収)の静加力実験に基づく性能評価，CMU架構の地震応答特性を解明する。
日本学術振興会, 基盤研究(B), 北海道大学, 25289177

筋かい付き架構の設計と耐震性能
鋼構造研究・教育助成事業
2014年04月 - 2016年03月
岡崎太一郎
日本鉄鋼連盟, 研究代表者, 競争的資金

経済性を増進した鋼構造柱梁接合部の開発
科学研究費助成事業
2012年04月 - 2015年03月
岡崎 太一郎
建築鋼構造の経済性を向上するために，柱にH形鋼を使用した柱梁接合部を考案した。角形鋼でなくH形鋼を柱に使用し、施工手順を簡略化することを期待した。柱フランジへの接合と柱ウェブへの接合の二体の実大試験体について、繰り返し載荷実験を実施したところ，角形鋼管柱への接合と遜色ない性能を示した。ただ、柱ウェブに接合した場合，初期剛性が10%小さく，塑性化後に柱ウェブと水平スチフナの変形が層間変形に大きく寄与した。有限要素法解析で実験結果を精度よく再現することに成功し、実験と解析の両方から、柱ウェブへの接合は，梁フランジと柱スチフナの突合せ溶接部が破断に起点となりやすいことが分かった。
日本学術振興会, 基盤研究(C), 北海道大学, 24560676

ロッキング制振建築構造システムの応用と展開
科学研究費助成事業
2010年 - 2012年
緑川 光正, 麻里 哲広, 小豆畑 達也, 石原 直, 岡崎 太一郎
柱の浮き上がりを伴うロッキング構造システムは,重力による鉛直荷重を活用して地震応答低減を図る。浮き上がりに伴って降伏するベースプレートを柱脚部に設置した架構を対象として,今まで地震応答低減効果を明らかにすると同時に課題も指摘してきている。本研究では,本構造システムの応用と展開を図ることを目的として,未だ解明されていない捩れ応答特性の解明,柱脚部浮き上がり架構の課題を克服するための新たな構造システムの提案,耐震設計に関する提言を行う。
日本学術振興会, 基盤研究(B), 北海道大学, 22360219

接着剤を適用した建築鋼構造接合部の開発
科学研究費助成事業
2010年 - 2011年
岡崎 太一郎
接着剤種と継手長さをパラメータとした65体の二面せん断継手引張試験を実行し、構造用接着剤を建築鋼構造に適用する可能性を考察した。2種の接着剤のうちの一方では、継手長さを十分に確保することで、鋼材の降伏強度を上まわる継手を実現した。この接着剤を使用した50体のうち3体の試験体が残り47体より25%低いせん断接着強さを示した。3体では凝集破壊より界面破壊が卓越し、残り47体では凝集破壊が卓越した。もう一方の接着剤では、付着長さに比例してせん断接着強さが低減し、完全に界面破壊に支配された。
日本学術振興会, 若手研究(B), 北海道大学, 22760430

International hybrid simulation of tomorrow's braced frame systems　　　　　　　　　　　　　　　
NEESR-SG
2006年 - 2011年
岡崎太一郎
アメリカ国立科学財団, 研究代表者, 競争的資金

Damage investigation and data collection for collapsed I-35WBridge　　　　　　　　　　　　　　　
SGER
2007年 - 2009年
岡崎太一郎
アメリカ国立科学財団, 研究代表者, 競争的資金

学士課程, 工学部

修士課程, 工学院

博士課程, 工学院