研究者データベース

岡崎 太一郎(オカザキ タイチロウ)
工学研究院 建築都市部門 先端空間性能
教授

基本情報

所属

  • 工学研究院 建築都市部門 先端空間性能

職名

  • 教授

学位

  • Ph.D.(The University of Texas at Austin, USA)

ホームページURL

J-Global ID

研究キーワード

  • 免震構造   耐震構造   接合部   鋼構造   

研究分野

  • 社会基盤(土木・建築・防災) / 建築構造、材料

職歴

  • 2017年04月 - 現在 Dalian University of Technology Visiting Professor
  • 2016年04月 - 現在 北海道大学 工学(系)研究科(研究院) 教授

所属学協会

  • 日本免震構造協会   米国土木学会   米国鋼構造協会   日本地震工学会   日本鋼構造協会   日本建築学会   

研究活動情報

論文

  • 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][通常論文]
  • 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][通常論文]
  • 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][通常論文]
     
    © 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.
  • A panelized residential roof system. I: Structural design.
    Susan Mantell, Giovanni Muoio, Jane Davidson, Carol Shield, BJ Siljenberg, Taichiro Okazaki
    Journal of Architectural Engineering, American Society of Civil Engineers 23 4 04017020-1 - 04017020-16 2017年12月 [査読有り][通常論文]
  • Xiaodong Ji, Yandong Wang, Junshan Zhang, Taichiro Okazaki
    ENGINEERING STRUCTURES 150 622 - 635 2017年11月 [査読有り][通常論文]
     
    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.
  • Xuchuan Lin, Taichiro Okazaki, Kazuhiro Hayashi, Masayoshi Nakashima
    JOURNAL OF STRUCTURAL ENGINEERING 143 2 04016159  2017年02月 [査読有り][通常論文]
     
    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.
  • Xiaodong Ji, Yandong Wang, Qifeng Ma, Taichiro Okazaki
    JOURNAL OF STRUCTURAL ENGINEERING 143 2 04016169  2017年02月 [査読有り][通常論文]
     
    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.
  • Xiaodong Ji, Yandong Wang, Qifeng Ma, Taichiro Okazaki
    JOURNAL OF STRUCTURAL ENGINEERING 142 2 04015114  2016年02月 [査読有り][通常論文]
     
    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.
  • Siavash Soroushian, E. Manos, Maragakis, Keri L. Ryan, Eiji Sato, Tomohiro Sasaki, Taichiro Okazaki, Gilberto Mosqueda
    Journal of Structural Engineering, American Society of Civil Engineers 142 2 04015131  2016年02月 [査読有り][通常論文]
  • 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][通常論文]
  • Taichiro Okazaki, Michael D. Engelhardt, Jong-Kook Hong, Chia-Ming Uang, Apostolos Drolias
    JOURNAL OF STRUCTURAL ENGINEERING 141 8 04014201  2015年08月 [査読有り][通常論文]
     
    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.
  • Jong-Kook Hong, Chia-Ming Uang, Taichiro Okazaki, Michael D. Engelhardt
    JOURNAL OF STRUCTURAL ENGINEERING 141 8 04014200  2015年08月 [査読有り][通常論文]
     
    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.
  • 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 2014年11月 [査読有り][通常論文]
  • Xuchuan Lin, Taichiro Okazaki, Masayoshi Nakashima
    Journal of Constructional Steel Research 101 469 - 481 2014年10月 [査読有り][通常論文]
  • 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][通常論文]
  • Gul Yigitsoy, Cem Topkaya, Taichiro Okazaki
    JOURNAL OF CONSTRUCTIONAL STEEL RESEARCH 96 14 - 25 2014年05月 [査読有り][通常論文]
     
    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.
  • Tsuyoshi Hikino, Taichiro Okazaki, Koichi Kajiwara, Masayoshi Nakashima
    JOURNAL OF STRUCTURAL ENGINEERING 139 11 1812 - 1822 2013年11月 [査読有り][通常論文]
     
    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.
  • Keith D. Palmer, Charles W. Roeder, Dawn E. Lehman, Taichiro Okazaki, Carol Shield
    JOURNAL OF STRUCTURAL ENGINEERING 139 8 1274 - 1284 2013年08月 [査読有り][通常論文]
     
    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.
  • Taichiro Okazaki, Dimitrios G. Lignos, Tsuyoshi Hikino, Koichi Kajiwara
    Journal of Structural Engineering, American Society of Civil Engineers 139 4 515 - 525 2013年04月 [査読有り][通常論文]
  • 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][通常論文]
  • Taichiro Okazaki, Dimitrios G. Lignos, Mitsumasa Midorikawa, James M. Ricles, Jay Love
    EARTHQUAKE SPECTRA 29 S1 S219 - S243 2013年03月 [査読有り][通常論文]
     
    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.
  • Xuchuan Lin, Taichiro Okazaki, Yu-Lin Chung, Masayoshi Nakashima
    JOURNAL OF CONSTRUCTIONAL STEEL RESEARCH 82 48 - 58 2013年03月 [査読有り][通常論文]
     
    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.
  • 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][通常論文]
  • 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 2012年09月 [査読有り][通常論文]
     
    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.
  • Kapil Mathur, Larry A. Fahnestock, Taichiro Okazaki, Matthew J. Parkolap
    JOURNAL OF STRUCTURAL ENGINEERING-ASCE 138 7 942 - 951 2012年07月 [査読有り][通常論文]
     
    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.
  • Casey R. Briscoe, Susan C. Mantell, Taichiro Okazaki, Jane H. Davidson
    ENGINEERING STRUCTURES 35 114 - 119 2012年02月 [査読有り][通常論文]
     
    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.
  • 松宮智央, 長江拓也, 鍾育霖, 岡崎太一郎, 福山國夫, 中島正愛
    日本建築学会構造論文集 77 671 85 - 94 2012年01月 [査読有り][通常論文]
  • Casey R. Briscoe, Susan C. Mantell, Jane H. Davidson, Taichiro Okazaki
    JOURNAL OF SANDWICH STRUCTURES & MATERIALS 13 1 23 - 58 2011年01月 [査読有り][通常論文]
     
    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.
  • Minmao Liao, Taichiro Okazaki, Roberto Ballarini, Arturo E. Schultz, Theodore V. Galambos
    JOURNAL OF STRUCTURAL ENGINEERING-ASCE 137 1 59 - 68 2011年01月 [査読有り][通常論文]
     
    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.
  • Jeffrey W. Berman, Taichiro Okazaki, Heidrun O. Hauksdottir
    JOURNAL OF STRUCTURAL ENGINEERING 136 5 543 - 553 2010年05月 [査読有り][通常論文]
     
    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.
  • Taichiro Okazaki, Brian J. Siljenberg, Carol K. Shield, Susan C. Mantell
    JOURNAL OF CONSTRUCTIONAL STEEL RESEARCH 65 8-9 1721 - 1730 2009年08月 [査読有り][通常論文]
     
    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.
  • Taichiro Okazaki, Michael D. Engelhardt, Apostolos Drolias, Eric Schell, Jong-Kook Hong, Chia-Ming Uang
    JOURNAL OF CONSTRUCTIONAL STEEL RESEARCH 65 7 1401 - 1412 2009年07月 [査読有り][通常論文]
     
    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.
  • Taichiro Okazaki, Michael D. Engelhardt
    JOURNAL OF CONSTRUCTIONAL STEEL RESEARCH 63 6 751 - 765 2007年06月 [査読有り][通常論文]
     
    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.
  • Taichiro Okazaki, Masayoshi Nakashima, Keiichiro Suita, Tomohiro Matusmiya
    EARTHQUAKE ENGINEERING & STRUCTURAL DYNAMICS 36 1 35 - 53 2007年01月 [査読有り][通常論文]
     
    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 2007年 [査読有り][通常論文]
  • Taichiro Okazaki, Dawei Liu, Masayoshi Nakashima, Michael D. Engelhardt
    JOURNAL OF STRUCTURAL ENGINEERING-ASCE 132 9 1334 - 1342 2006年09月 [査読有り][通常論文]
     
    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.
  • Taichiro Okazaki, Michael D. Engelhardt, Masayoshi Nakashima, Keiichiro Suita
    Journal of Structural Engineering, American Society of Civil Engineers 132 8 1201 - 1211 2006年08月 [査読有り][通常論文]
  • T Okazaki, G Arce, HC Ryu, MD Engelhardt
    JOURNAL OF STRUCTURAL ENGINEERING-ASCE 131 10 1526 - 1535 2005年10月 [査読有り][通常論文]
     
    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.
  • 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][通常論文]
  • 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][通常論文]
  • 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][通常論文]
  • T Nonaka, RJ Clifton, T Okazaki
    INTERNATIONAL JOURNAL OF IMPACT ENGINEERING 18 7-8 889 - 898 1996年10月 [査読有り][通常論文]
     
    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.

書籍

  • 日本建築学会:鋼構造許容応力度設計規準
    岡崎太一郎 (担当:共著範囲:1章から6章)
    丸善出版 2019年10月
  • AIJ Design Standard for Steel Structures ― Based on Allowable Stress Concept― (2005 Edition)
    岡崎太一郎 (担当:共訳範囲:1章から4章)
    Architectural Institute of Japan 2017年10月
  • 日本建築学会:鋼構造塑性設計指針(第4版)
    岡崎太一郎 (担当:共著範囲:7章)
    丸善出版 2017年02月
  • 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 (担当:共著範囲:2.2節、4.1節)
    丸善出版 2015年12月
  • JSSC Sets of Torshear Type High-Strength Bolt, Hexagon Nut and Plain Washer for structural Joints (English translation)
    岡崎太一郎 (担当:共著範囲:全体)
    日本鋼構造協会

講演・口頭発表等

  • 地震と鋼材―阪神・淡路大地震から25年を過ぎて―  [招待講演]
    岡崎太一郎
    第71回白石記念講座 2019年11月 公開講演,セミナー,チュートリアル,講習,講義等
  • Contribution of Academic Research to the Seismic Safety of Steel Structures in Japan.  [招待講演]
    岡崎太一郎
    16th Symposium on Earthquake Engineering (India) 2018年12月 口頭発表(基調)
  • Seismic Design Procedure of Steel Structures in Japan: Past, Present, and Future  [招待講演]
    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 口頭発表(招待・特別)
  • Japanese Research on Super-High-Strength Structural Steel  [招待講演]
    Taichiro OKAZAKI, Hidenori FUKAMI, Masato OHATA, Masayoshi NAKASHIMA
    NASCC: The Steel Conference 2012年04月 口頭発表(一般)

その他活動・業績

  • 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 [査読無し][通常論文]
  • 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 [査読無し][通常論文]
  • 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 [査読無し][通常論文]
  • 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 26 196 -203 2018年11月 [査読有り][通常論文]
  • 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 [査読無し][通常論文]
  • 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 [査読無し][通常論文]
  • 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][通常論文]
  • 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][通常論文]
  • 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][通常論文]
  • 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][通常論文]
  • 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][通常論文]
  • Cyclic loading behavior of steel chevron braced frames
    Taichiro Okazaki, Hayato Asada, Mitsumasa Midorikawa, Tetsuhiro Asari 16th World Conference on Earthquake Engineering (16WCEE) No. 2635 2017年01月 [査読無し][通常論文]
  • 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 [査読無し][通常論文]
  • 井上桂輔、構造用接着剤を用いた鋼梁継手の曲げせん断実験
    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][通常論文]
  • Sanputt Simasathien, Shih-Ho Chao, Kevin Moore, Taichiro Okazaki 10th U.S. National Conference on Earthquake Engineering (10NCEE) No. 1126 2014年07月 [査読無し][通常論文]
  • Sanputt Simasathien, Chatchai Jiansinlapadamrong, Taichiro Okazaki, Shih-Ho Chao 10th U.S. National Conference on Earthquake Engineering (10NCEE) No. 1109 2014年07月 [査読無し][通常論文]
  • Taichiro Okazaki, Eiji Sato, Keri L. Ryan, Tomohiro Sasaki, Stephen Mahin 10th U.S. National Conference on Earthquake Engineering (10NCEE) No. 114 2014年07月 [査読無し][通常論文]
  • 岡崎太一郎 建築技術 (754) 122-123 2012年11月01日 [査読無し][通常論文]
  • 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 [査読無し][招待有り]
  • 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 [査読無し][通常論文]
  • 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 [査読無し][通常論文]
  • 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 [査読無し][通常論文]
  • 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 [査読無し][通常論文]
  • 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 [査読無し][通常論文]

共同研究・競争的資金等の研究課題

  • 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:基盤研究(B)
    研究期間 : 2017年04月 -2020年03月 
    代表者 : 岡崎太一郎
  • 筋かい付き架構の設計と耐震性能
    日本鉄鋼連盟:鋼構造研究・教育助成事業
    研究期間 : 2014年04月 -2016年03月 
    代表者 : 岡崎太一郎
  • 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:基盤研究(C)
    研究期間 : 2012年04月 -2015年03月 
    代表者 : 岡崎太一郎
  • International hybrid simulation of tomorrow's braced frame systems
    アメリカ国立科学財団:NEESR-SG
    研究期間 : 2006年 -2011年 
    代表者 : 岡崎太一郎
  • Damage investigation and data collection for collapsed I-35WBridge
    アメリカ国立科学財団:SGER
    研究期間 : 2007年 -2009年 
    代表者 : 岡崎太一郎
  • 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:若手(B)
    代表者 : 岡崎太一郎

教育活動情報

主要な担当授業

  • Advanced Structural Analysis(建築構造解析E)
    開講年度 : 2018年
    課程区分 : 修士課程
    開講学部 : 工学院
    キーワード : 構造解析、非線形解析、塑性解析、マトリックス解析、コンピュータ解析
  • Special Lectures on Engineering Ⅱ
    開講年度 : 2018年
    課程区分 : 修士課程
    開講学部 : 工学院
    キーワード : 構造解析、非線形解析、塑性解析、マトリックス解析、コンピュータ解析
  • 建築構造解析特論
    開講年度 : 2018年
    課程区分 : 修士課程
    開講学部 : 工学院
    キーワード : 構造解析、非線形解析、塑性解析、マトリックス解析、コンピュータ解析
  • Advanced Structural Analysis(建築構造解析E)
    開講年度 : 2018年
    課程区分 : 博士後期課程
    開講学部 : 工学院
    キーワード : 構造解析、非線形解析、塑性解析、マトリックス解析、コンピュータ解析
  • 建築構造解析特論
    開講年度 : 2018年
    課程区分 : 博士後期課程
    開講学部 : 工学院
    キーワード : 構造解析、非線形解析、塑性解析、マトリックス解析、コンピュータ解析
  • 建築構造動力学
    開講年度 : 2018年
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 動力学,耐震工学,強震動,離散系,耐震基準
  • 建築算法
    開講年度 : 2018年
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : フーリエ変換,デルタ関数,高速フーリエ変換,時間,周波数,振動
  • 構造解析Ⅰ
    開講年度 : 2018年
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 動力学,耐震工学,強震動,離散系,耐震基準
  • 構造力学Ⅰ
    開講年度 : 2018年
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 構造設計 モデル 荷重 断面力 釣り合い 静定構造物 断面特性 応力
  • 構造力学Ⅱ
    開講年度 : 2018年
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 構造 解析 変形 不静定構造物 梁 ラーメン トラス
  • 構造力学Ⅲ
    開講年度 : 2018年
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 構造 解析 マトリックス法 塑性解析

大学運営

委員歴

  • 2019年08月 - 現在   日本建築学会   鋼構造次世代設計規準検討WG
  • 2019年07月 - 現在   日本建築学会   構造基準の社会ニーズ対応WG・委員
  • 2019年04月 - 現在   日本建築学会   合成構造運営委員会・委員
  • 2016年06月 - 現在   北海道地区自然災害科学資料センター   北海道地区幹事
  • 2016年06月 - 現在   日本鋼構造協会   建築鋼構造研究ネットワーク・北海道地区幹事
  • 2015年04月 - 現在   日本建築学会   鋼構造関連規準・指針の英文化小委員会・主査
  • 2014年12月 - 現在   日本建築学会   鋼構造塑性設計小委員会・委員
  • 2014年12月 - 現在   日本建築学会   鋼構造運営委員会・委員
  • 2013年06月 - 現在   日本地震工学会   IAEE事務局支援委員会・委員
  • 2012年04月 - 現在   日本建築学会   鋼構造環境小委員会・主査(2019.4~)
  • 2011年04月 - 現在   日本建築学会   北海道支部 構造専門委員会・委員
  • 2017年06月 - 2019年05月   日本建築学会   理事会・学術理事
  • 2016年06月 - 2019年03月   日本建築学会   鋼構造設計規準改定小委員会・幹事
  • 2016年06月 - 2018年05月   日本建築学会   北海道支部:支部研究会実行委員長
  • 2015年06月 - 2017年05月   日本鋼構造協会   JSSトルシア形高力ボルト(英語版規格)改正小委員会・委員
  • 2015年06月 - 2017年05月   日本地震工学会   大会実行委員会・委員
  • 2013年12月 - 2017年01月   日本地震工学会   17WCEE誘致委員会・委員
  • 2014年06月 - 2016年05月   日本建築学会   北海道支部理事会・常任幹事
  • 2013年06月 - 2015年05月   日本建築学会   技術報告集委員会・委員
  • 2012年08月 - 2013年09月   日本建築学会   北海道大会実行委員会・委員
  • 2011年11月 - 2013年05月   日本地震工学会   国際委員会・委員
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