SEARCH
Search Details
OKUI Yoshiaki
| Environmental Science and Civil Engineering Division | Professor |
| Department of Civil and Environmental Engineering | Dean |
Performance information
■ Paper- A STUDY ON RATIONALIZATION OF BRIDGE STEEL EXPANSION JOINT
Masami MATSUNO; Taro TONEGAWA; Yoshiaki OKUI
Japanese Journal of JSCE, Volume：79, Number：11, First page：n/a, Last page：n/a, Nov. 2023, [Reviewed]
Japan Society of Civil Engineers, Japanese, Scientific journal
DOI：https://doi.org/10.2208/jscejj.22-00332
DOI ID：10.2208/jscejj.22-00332, eISSN：2436-6021 - System redundancy of steel I‐girder bridges and proposal of a system factor for load rating
Yoshiaki Okui; Makoto Denda; Kazuki Kumaki; Satoshi Sakuma
ce/papers, Volume：6, Number：3-4, First page：964, Last page：969, Sep. 2023, [Reviewed], [Lead, Corresponding]
Abstract
3D nonlinear FE analyses of existing plate‐girder bridges were carried out to investigate system redundancy. A comparison of the ultimate live load factors between a whole bridge system (WBS) model and a single girder (SG) model shows that WBS's ultimate live load factor is larger than SG's factor. This difference in the ultimate load factors is interpreted as the system redundancy effect. A system factor to quantify the system redundancy has been proposed based on the nonlinear FE analysis results. The proposed system factor is defined as a factor to convert the ultimate live load factor and rating factor for load rating based on linear analysis into those based on nonlinear analysis. A case study to calculate the system factor for three existing bridges shows dependency of the system factor on the number of girders, composite/non‐composite girders, simple span/continuous span.
Wiley, Scientific journal
DOI：https://doi.org/10.1002/cepa.2276
DOI ID：10.1002/cepa.2276, ISSN：2509-7075, eISSN：2509-7075 - LOAD-CARRYING CAPACITY AND CRACK WIDTH CONTROL FOR LIMIT STATE DESIGN METHOD OF COMPOSITE BRIDGES
Yoshiaki OKUI
Japanese Journal of JSCE, Volume：79, Number：14, First page：n/a, Last page：n/a, May 2023, [Reviewed], [Lead, Corresponding]
Japan Society of Civil Engineers, Japanese, Scientific journal
DOI：https://doi.org/10.2208/jscejj.22-14001
DOI ID：10.2208/jscejj.22-14001, eISSN：2436-6021 - 既設橋評価のための実態交通荷重を考慮した活荷重係数に関する研究
Toru Kasamatsu; Yoshiaki Okui; Masashi Kimura; Ryota Kano; Satoru Sakuma; Hideo Tokida
構造工学論文集, Volume：69A, First page：58, Last page：68, Apr. 2023, [Reviewed]
Japanese - 鋼橋のシステムリダンダンシーの評価方法とLoad ratingにおけるシステム係数の提案
奥井 義昭, 傳田 諒, 熊木 和輝, 佐久間 智
構造工学論文集 Ａ, Volume：68A, First page：1, Last page：10, 2022, [Invited], [Lead]
Japanese, Scientific journal - A STUDY ON LOAD-CARRYING CAPACITY EVALUATION OF EXISTING BRIDGES USING LOAD RATING
Toru KASAMATSU; Yoshiaki OKUI; Masahiro ISHIBASHI; Hajime YAMAKAWA
Journal of Japan Society of Civil Engineers, Ser. A1 (Structural Engineering & Earthquake Engineering (SE/EE)), Volume：77, Number：3, First page：418, Last page：426, Nov. 2021, [Reviewed]
Japan Society of Civil Engineers, Japanese, Scientific journal
DOI：https://doi.org/10.2208/jscejseee.77.3_418
DOI ID：10.2208/jscejseee.77.3_418, eISSN：2185-4653 - 鋼橋の強靱化・長寿命化に向けた研究の取組み
舘石 和雄,奥井 義昭,村越 潤,穴見 健吾,岩崎 英治
橋梁と基礎, Volume：55, Number：2, First page：16, Last page：21, 2021 - 鋼道路橋のLoad Ratingの検討
奥井 義昭,宮下 剛
橋梁と基礎, Volume：55, Number：2, First page：23, Last page：26, 2021 - 鋼橋の設計・評価技術の高度化, JSSC Topics 委員会活動とその成果
奥井義昭
Journal of Steel Structures & Construction, Volume：No.46, First page：41, Last page：42, 2021 - Probabilistic Compressive Strength of Stiffened Steel Plates Exhibiting Column-Like Behavior: Ultimate and Serviceability Limit States
Mahmudur Rahman; Yoshiaki Okui; Masato Komuro; Muhammad Atif Anwer; Azusa Numata
Journal of Structural Engineering, Volume：146, Number：9, First page：04020166, Last page：1-04020166-15, Sep. 2020, [Reviewed]
American Society of Civil Engineers (ASCE), Scientific journal
DOI：https://doi.org/10.1061/(asce)st.1943-541x.0002719
DOI ID：10.1061/(asce)st.1943-541x.0002719, ISSN：0733-9445, eISSN：1943-541X - Flexural Capacity Accounting for SBHS500 Steel of Composite Bridge Girders
Dang Viet Duc; Yoshiaki Okui
Lecture Notes in Civil Engineering, Volume：54, First page：209, Last page：214, 2020
The positive bending moment capacity of composite steel girders is examined through study employing elasto-plastic FE analyses. The web slenderness limits of section classification for homogeneous and hybrid girders with bridge high performance steel are explored. Besides, the effects of initial bending moment due to unshored construction method on the web slenderness limit are investigated. It is shown that the noncompact web slenderness limits in conventional design standards are conservative for composite sections.
Springer, English, In book
DOI：https://doi.org/10.1007/978-981-15-0802-8_30
DOI ID：10.1007/978-981-15-0802-8_30, ISSN：2366-2565, SCOPUS ID：85073688541 - THE LIMIT STATES COMPRESSIVE STRENGTH ESTIMATION FOR SIMPLE STIFFENED PLATE WITH LARGE ASPECT RATIO
MIYAZAKI Yasuhiro; RAHMAN Mahmudur; OKUI Yoshiaki
Journal of Japan Society of Civil Engineers, Ser. A1 (Structural Engineering & Earthquake Engineering (SE/EE)), Volume：76, Number：1, First page：67, Last page：81, 2020, [Reviewed]The compressive strengths of stiffened plates with a single longitudinal stiffener were examined from experimental and numerical results. First, totally four compressive loading tests of rectangular short columns consisting of four stiffened plates were carried out for two different slenderness parameters and two steel grades, namely ordinary steel SM490Y and bridge high-performance steel SBHS500. During the loading test, compressive load and longitudinal displacement as well as out-of-plane displacements were monitored. The adequacy of a nonlinear finite element model was verified using the test results, and it was confirmed that the developed analysis model reproduced the compressive behavior with sufficient accuracy. Finally, both mean and standard deviation of the ultimate as well as serviceability limit strengths are reported in comparison with road bridge specifications, such as AASHTO, Canadian Code and Eurocode.
Japan Society of Civil Engineers, Japanese, Scientific journal
DOI：https://doi.org/10.2208/jscejseee.76.1_67
DOI ID：10.2208/jscejseee.76.1_67, CiNii Articles ID：130007787666 - Seismic response of isolated bridge with high damping rubber bearings: Self-heating effect at subzero temperatures
Yoshiaki Okui; Keisuke Nakamura; Takashi Sato; Takashi Imai
Steel Construction,, Volume：12, Number：1, First page：2, Last page：9, Jan. 2019, [Reviewed], [Invited]
English, Scientific journal - SM570を使用したコンクリート充填鋼製橋脚の 地震時変形性能に関する実験的研究
神田信也,松原拓朗,田嶋仁志,奥井義昭,志治謙一,岡田誠司
構造工学論文集, Volume：64A, First page：222, Last page：230, Mar. 2018, [Reviewed]
Japanese, Scientific journal - Reliability Based Design for Buckling Strength of Stiffened Steel Plates: Ultimate and Serviceability Limit States
Rahman, M. and Okui, Y.
Proc. of 11th ADB-JSP Research Forum, Tokyo, Japan, 2018 - 次の橋梁設計基準が目指すべきもの
奥井義昭
宮地技報, Volume：31, First page：1, Last page：3, 2018 - Probabilistic column-like buckling strength for stiffened steel plates under uniaxial compression
Rahman, M., Okui, Y. and Komuro, M.
Proc. of JSCE 20th Int'l Summer Symposium, Hokkaido, Japan, First page：3, Last page：4, 2018 - An Experimental Study on Seismic Performance of Concrete-Filled Steel Piers
Shinya Kanda; Takuro Matsubara; Hitoshi Tajima; Yoshiaki Okui; Kenichi Shiji; Seiji Okada
Proc. of 40th IABSE Symposium, First page：S23-125, Last page：S23-132, 2018, [Reviewed]
English, International conference proceedings - Probabilistic strength at serviceability limit state for normal and SBHS slender stiffened plates under uniaxial compression
Mahmudur Rahman; Yoshiaki Okui; Muhammad Atif Anwer
International Journal of Steel Structures, Volume：18, Number：4, First page：1397, Last page：1409, 2018, [Reviewed]
English, Scientific journal - Probabilistic ultimate buckling strength of stiffened plates, considering thick and high-performance steel
Mahmudur Rahman; Yoshiaki Okui; Takahiro Shoji; Masato Komuro
JOURNAL OF CONSTRUCTIONAL STEEL RESEARCH, Volume：138, First page：184, Last page：195, Nov. 2017, [Reviewed]
The probabilistic distribution of ultimate buckling strength for stiffened steel plates subjected to a distributed axial stress was obtained using Monte Carlo simulations in association with the response surface method. The plates of both normal and high-performance steel (SBHS) were taken into account, and their thickness was varied from 10 to 90 mm. The ultimate buckling strength was determined by nonlinear elasto-plastic finite element (FE) analysis, considering geometric and material nonlinearity. The initial out-of-plane deflection and residual stress were considered as two independent random variables upon which the ultimate buckling strength depends. The response surface, showing the variation of ultimate strength due to the initial deflection and residual stress, was estimated using the nonlinear FE results. Based on the obtained statistical distribution, partial safety factors for the ultimate buckling strength were proposed. (C) 2017 Elsevier Ltd. All rights reserved.
ELSEVIER SCI LTD, English, Scientific journal
DOI：https://doi.org/10.1016/j.jcsr.2017.07.004
DOI ID：10.1016/j.jcsr.2017.07.004, ISSN：0143-974X, eISSN：1873-5983, Web of Science ID：WOS:000418213100013 - TEMPERATURE DEPENDENCE OF MECHANICAL BEHAVIOR OF HIGH DAMPING RUBBER BEARINGS CONSIDERING SELF HEATING
Yoshiaki OKUI; Yasuhiro ONOUE; Takashi SATO; Takashi IMAI
木学会論文集A1（構造・地震工学）, Volume：73, Number：1, First page：165, Last page：173, Feb. 2017, [Reviewed]
Scientific journal - An improved rheology model for the description of the rate-dependent cyclic behavior of high damping rubber bearings
D. A. Nguyen; J. Dang; Y. Okui; A. F. M. S. Amin; S. Okada; T. Imai
SOIL DYNAMICS AND EARTHQUAKE ENGINEERING, Volume：77, First page：416, Last page：431, Oct. 2015, [Reviewed]
An improved rheology model, inspired from explicit experiments is conceived to represent rate-dependent cyclic shear behavior of high damping rubber bearings at subzero and room temperatures. Total stress has been decomposed into nonlinear rate independent elasto-plastic stress, nonlinear elastic stress and nonlinear visco-elasto-plastic overstress branches. To represent nonlinear viscosity behavior, 'overstress branch' has been generalized by putting linear elastic spring in parallel to nonlinear elasto-plastic model, placed in series with nonlinear dashpot. Constitutive relations for model elements have been designated for respective fundamental phenomenon observed in constant strain rate experiments. An optimum calculation approach is developed to determine a unique set of overstress parameters capable not only of representing constant strain rate cyclic tests but also sinusoidal tests with variable input strain rates. Essential abilities of the proposed model and adequacy of estimated parameters have been confirmed by comparing numerical simulation results with experiments conducted at -30 degrees C, -10 degrees C and 23 degrees C. (C) 2015 Elsevier Ltd. All rights reserved.
ELSEVIER SCI LTD, English, Scientific journal
DOI：https://doi.org/10.1016/j.soildyn.2015.06.001
DOI ID：10.1016/j.soildyn.2015.06.001, ISSN：0267-7261, eISSN：1879-341X, Web of Science ID：WOS:000360420000039 - Nonlinear Viscosity Law in Finite-Element Analysis of High Damping Rubber Bearings and Expansion Joints
A. F. M. S. Amin; A. R. Bhuiyan; T. Hossain; Y. Okui
JOURNAL OF ENGINEERING MECHANICS, Volume：141, Number：6, First page：04014169, Last page：1-11, Jun. 2015, [Reviewed]
A simple computational strategy for finite-element implementation of a finite-strain viscohyperelasticity model for rubber-like materials was developed. The constitutive model has had a strong physical significance because of the explicit consideration of the nonlinear dependence of viscosity through internal variables (e.g., past maximum overstress and current deformation). To simulate the stress-strain response for particular one-dimensional boundary value problems, a scheme for solving the first-order differential equation representing the viscosity-induced strain-rate effect of rubber was proposed. The scheme was successful in reproducing experimental results obtained from high-damping rubber specimens. In addition, the wider applicability of the proposed strategy in simulation was tested by verifying the numerical results with independent experiments on full-scale high-damping rubber bearings with different geometries and loading rates. The effect of shape factor on bearing responses was examined through numerical examples obtained from different finite-element models subjected to the same load and loading rate. Finally, the proposed computational strategy was applied to locate the regions of stress concentrations in steel plate laminated rubber expansion joints used widely to transfer reactions at central-hinge locations on balanced cantilever highway bridges. (C) 2014 American Society of Civil Engineers.
ASCE-AMER SOC CIVIL ENGINEERS, English, Scientific journal
DOI：https://doi.org/10.1061/(ASCE)EM.1943-7889.0000888
DOI ID：10.1061/(ASCE)EM.1943-7889.0000888, ISSN：0733-9399, eISSN：1943-7889, Web of Science ID：WOS:000354551500009 - Ultimate strength curves of compressive member with box sections in real steel bridges
Nogami Kuniei; Takeuchi Yukiharu; Yamashita Youhei; Kishi Yusuke; Nagai Masatsugu; Okui Yoshiaki; Nozaka Katsuyoshi; komuro Masato; Miyashita Takeshi
Kozo Kogaku Ronbunshu. A (Journal of Structural Engineering. A), Volume：61, First page：35, Last page：48, Mar. 2015, [Reviewed]
This paper describes the discussions on the ultimate strength characteristics for existing compression members of steel truss and arch bridges, and proposes new ultimate strength curve of welded box-section members. The investigation objects are section size, material, initial imperfections, stiffener size of compression member which designed based on Spec. for Highway Bridges 2002. In addition, ultimate strength characteristics of existing compression members with box-section are calculated for several steel types. The results of investigations shows that the 0.2σy is able to apply as upper limit of compression residual stress (σrc) for HTSS members. The results of numerical analyses provide the ultimate strength characteristics of welded box-section compression members for steel truss and arch bridges. Moreover, new ultimate strength curve is proposed for the compression members in this research.
Japan Society of Civil Engineers, Japanese
DOI：https://doi.org/10.11532/structcivil.61A.35
DOI ID：10.11532/structcivil.61A.35, ISSN：1881-6614, CiNii Articles ID：130005439094, CiNii Books ID：AA12210243 - 既設構造物の性能評価 −臨床構造工学−
奥井義昭
土木学会誌, Volume：Vol.100, No.10, First page：16, Last page：17, 2015 - 鋼多主桁橋の非線形リダンダンシー解析
見原理一; 加藤 修; 岩崎英治; 奥井義昭
Volume：17, Number：1, First page：77, Last page：88, Aug. 2014
Japanese, International conference proceedings - リダンダンシー評価ガイドラインと今後の展望
吉岡 勉; 奥井義昭; 岩崎英治
Volume：17, Number：1, First page：97, Last page：104, Aug. 2014
Japanese, International conference proceedings - Numerical study on ultimate strength of compressive flange considering statistical data for distributions of initial displacement and residual stress
Komuro Masato; Okui Yoshiaki; Nozaka Katsuyoshi; Miyashita Takeshi; Nogami Kuniei; Nagai Masatsugu
Kozo Kogaku Ronbunshu. A (Journal of Structural Engineering. A), Volume：60, First page：80, Last page：93, Mar. 2014, [Reviewed]
The ultimate strengths of compressive steel plates simply supported on three sides and one side free (outstanding plates) were numerically investigated by means of combining FE elasto-plastic analysis and Monte Carlo simulation considering the statistical data for variability of the initial displacement and residual stress. From this study, the following results were obtained: (1) a standard deviation of the ultimate strength tends to increase in the region of the with-thickness ratio parameter R ≅ 1.0; (2) in the region of R < 0.7, the effect of the residual stress on the ultimate strength is very small; and (3) considering the statistical data for variability of the initial displacement and residual stress of the plate, a rational design formula can be proposed.
Japan Society of Civil Engineers, Japanese
DOI：https://doi.org/10.11532/structcivil.60A.80
DOI ID：10.11532/structcivil.60A.80, ISSN：1881-6614, CiNii Articles ID：130005439004 - Probabilistic distributions of plate buckling strength for normal and bridge high-performance steels
Dang Viet Duc; Yoshiaki Okui; Koichi Hagiwara; Masatsugu Nagai
INTERNATIONAL JOURNAL OF STEEL STRUCTURES, Volume：13, Number：3, First page：557, Last page：567, Sep. 2013, [Reviewed]
The probabilistic distributions of buckling strengths for compressive plates of normal and bridge high-performance steels were obtained through numerical analyses in order to develop a nominal design strength and a corresponding safety factor. In the numerical analyses, Monte Carlo simulation was used in combination with the response surface method to reduce the effort associated with the finite element analyses. For each value of the slenderness parameter R, a response surface of the normalized local bucking strength was determined based on the results of 114 finite element analyses using different residual stresses and initial defections. The response surface is approximated as a simple algebraic function of the residual stress and the initial deflection. Monte Carlo simulation is then carried out in order to evaluate the probabilistic distribution of the local bucking strength. The mean values obtained in the present study approach those of a mean curve proposed based on experiments. The standard deviation of the present study was approximately half that obtained based on experimental results in the range of 0.6 < R < 1.2.
KOREAN SOC STEEL CONSTRUCTION-KSSC, English, Scientific journal
DOI：https://doi.org/10.1007/s13296-013-3014-1
DOI ID：10.1007/s13296-013-3014-1, ISSN：1598-2351, eISSN：2093-6311, Web of Science ID：WOS:000325702000014 - Experimental study on the strength of SBHS I-girder
Nozaka Katsuyoshi; Okui Yoshiaki; Komuro Masato; Miyashita Takeshi; Nogami Kuniei; Nagai Masatsugu
Kozo Kogaku Ronbunshu. A (Journal of Structural Engineering. A), Volume：59, First page：70, Last page：79, Mar. 2013, [Reviewed]
Recently, High Performance Steel, HPS, especially for bridge construction has been developed, named SBHS. Although SBHS has high strength and high weldability, SBHS steel has not been widely adopted in bridge constructions in Japan, because SBHS steel has not been specified in the Specifications for Highway Bridges in Japan. In this research, bending and shear strength of SBHS I-girder were experimentally investigated, and test results indicated that SBHS I-giders can be designed safely using concepts adopted in current specifications. In addition, residual stress distriutions in SBHS I-girder were measured to confirm no negative impact exist against the strength.
Japan Society of Civil Engineers, Japanese
DOI：https://doi.org/10.11532/structcivil.59A.70
DOI ID：10.11532/structcivil.59A.70, CiNii Articles ID：130005438822 - Mechanical behavior of high damping rubber bearings at low temperatures
Dung Anh NGUYEN, Yoshiaki OKUI, Md. Shafquat HASAN, Hiroshi MITAMURA, Takashi IMAI
Proc. of International Symposium on New Technologies for Urban Safety of Mega Cities in Asia, Volume：Paper id 2-150, First page：1, Last page：8, 2013 - Low temperature behavior and modeling of high damping rubber bearings
Tomoya MATSUMOTO, Yoshiaki OKUI, Dung Anh NGUYEN, Md. Shafquat HASAN, Kaho TAKAHASHI, Hiroshi MITAMURA, Takashi IMAI
Proc. of International Symposium on New Technologies for Urban Safety of Mega Cities in Asia, Volume：Paper id 4-067, First page：1, Last page：8, 2013 - 限界状態設計法と維持管理
奥井義昭
片山技報, Volume：33, First page：2, Last page：7, 2013 - プレキャスト床版連続合成桁のずれ止めに関する実験および解析
大城 壮司, 上條 崇, 奥井 義昭, 長井 正嗣
土木学会論文集A1（構造・地震工学）, Volume：68, Number：2, First page：331, Last page：346, 2012, [Reviewed]
Scientific journal - Application of Rheology Modeling to Natural Rubber and Lead Rubber Bearings: A Simplified Model and Low Temperature Behavior
Muhammad Kashif RAZZAQ, Yoshiaki OKUI, Abdur Rahman BHUIYAN, A. F. M. Saiful AMIN, Hiroshi MITAMURA, Takashi IMAI
Journal of Japan Society of Civil Engineers, Ser. A1 (Structural Engineering & Earthquake Engineering (SE/EE)), Volume：68, Number：3, First page：526, Last page：541, 2012, [Reviewed]
Scientific journal - Design, construction and maintenance of steel and steel-concrete hybrid bridges in Japan
Nagai, M., Okui, Y., Miyashita, T.,
Festschrift Gerhard Hanswille, Institut f:ur Konstruktven Ingenieurbau, Bergische Universit:at Wuppertal, Volume：Heft 20, First page：293, Last page：302, 2011 - Bending Moment Capacity and Combined Strength under Bending Moment and Shear for Composite Girders
Duc, D.V. Okui, Y., Nagai, M., Inaba, N. Homma, A.
Proc. of the 6th International Symposium on Steel Structures, First page：941, Last page：947, 2011, [Reviewed] - プレキャスト床版連続合成桁の曲げひび割れ幅に関する実験
大城壮司、上條崇、奥井義昭、長井正嗣
構造工学論文集A, Volume：56A, First page：1027, Last page：1040, 2010
土木学会, Scientific journal - 2重合成I桁の曲げ及びせん断強度の評価方法に関する実験的研究
稲葉尚文、奥井義昭、長井正嗣、本間淳史、春日井俊博、野呂直以
土木学会論文集A, Volume：66, Number：1, First page：117, Last page：132, 2010, [Reviewed]
土木学会, Scientific journal - Experimental Study of Rate-Dependent Mechanical Behavior of Laminated Rubber Bearings
T.Imai, A.R.Bhuiyan, M.K.Razzaq, Y.Okui, H.Mitamura
Joint Conf. Proc. of 7th Int. Conf. on Urban Earthquake Eng. & 5th Int. Conf. on Earthquake Eng., First page：1921, Last page：1928, 2010
7th CUEE and 5th ICEE Joint Conference - 合成I桁の曲げ，せん断相関強度解明に関する実験的研究
稲葉尚文,奥井義昭,長井正嗣,本間淳史,春日井俊博,野呂直以
土木学会論文集Ａ, Volume：66, Number：2, First page：393, Last page：405, 2010, [Reviewed]
土木学会, Scientific journal - A rheology model of high damping rubber bearings for seismic analysis: Identification of nonlinear viscosity
A. R. Bhuiyan; Y. Okui; H. Mitamura; T. Imai
INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES, Volume：46, Number：7-8, First page：1778, Last page：1792, Apr. 2009, [Reviewed]
The mechanical behavior of high damping rubber bearings (HDRBs) is investigated under horizontal cyclic shear deformation with a constant vertical compressive load. On the basis of experimental observations, an elasto-viscoplastic rheology model of HDRBs for seismic analysis is developed. In this model, the Maxwell model is extended by adding a nonlinear elastic spring and an elasto-plastic model (spring-slider) in parallel. In order to identify constitutive relations of each element in the rheology model, an experimental scheme comprised of three types of tests, namely a cyclic shear (CS) test, a multi-step relaxation (MSR) test, and a simple relaxation (SR) test, are carried out at room temperature. HDRB specimens with the standard ISO geometry and three different high damping rubber materials are employed in these tests. A nonlinear viscosity law of the dashpot in the Maxwell model is deduced from the experimental scheme, and incorporated into the rheology model to reproduce the nonlinear rate dependent behavior of HDRBs. Finally, numerical simulation results for sinusoicial loading are presented to illustrate capability of the proposed theology model in reproducing the mechanical behavior of HDRBs. (C) 2009 Elsevier Ltd. All rights reserved.
PERGAMON-ELSEVIER SCIENCE LTD, English, Scientific journal
DOI：https://doi.org/10.1016/j.ijsolstr.2009.01.005
DOI ID：10.1016/j.ijsolstr.2009.01.005, ISSN：0020-7683, CiNii Articles ID：120001371436, Web of Science ID：WOS:000264573700019 - ハイブリッド桁の限界状態設計法試案
長井正嗣、押下里治、奥井義昭他
JSSCテクニカルレポート, Number：83, 2009
日本鋼構造協会 - Effect of Rubber Bearing's Modeling on Seismic Response of Base Isolated Highway Bridge
M.K.Razzaq, A.R.Bhuiyan, Y.Okui, H.Mitamura, and T.Imai
Joint Conf. Proc. of 7th Int. Conf. on Urban Earthquake Eng. & 5th Int. Conf. on Earthquake Eng., First page：1855, Last page：1862, 2009
7th CUEE and 5th ICEE Joint Conference - Ultimate flexure and shear strength of I-girder under hogging bending moment in double-composite girder bridges
Masatsugu Nagai; Naofumi Inaba; Yoshiaki Okui
STEEL CONCRETE COMPOSITE AND HYBRID STRUCTURES, First page：195, Last page：200, 2009, [Reviewed]
In continuous composite girder bridges, in case that the concrete slab is installed on the lower flange at intermediate Supports, it has been called "double-composite girder bridges". At serviceability limit and ultimate limit states, the load carrying section is assumed consisting of three components, such as steel I-girder, reinforcing bars (encased in upper deck concrete) and the concrete block installed on the lower steel flange of I-girder. This paper proposes formula for evaluating ultimate flexural strength and shear strength of I-girder at intermediate supports in double-composite girder bridges.
RES PUBL SERV, English, International conference proceedings
Web of Science ID：WOS:000273559400020 - 低塔を有する200ｍ合成斜張橋の弾塑性挙動と終局強度
井尾伸太郎; 野上邦栄; 奥井義昭; 森園康之
複合・合成構造の活用に関するシンポジウム論文報告, Volume：8, First page：41-1-41-6, Last page：1-41-6, 2009
土木学会 - 我国の鋼トラス橋を対象としたリダンダンシー解析の検討
永谷; 秀樹 . 明石; 直光 . 松田; 岳憲 . 安田; 昌宏 . 石井; 博典 . 宮森; 雅之 . 小幡; 泰弘 . 平山; 奥井義昭; 義
土木学会論文集Ａ, Volume：65, Number：2, First page：410, Last page：425, 2009
鋼トラス橋梁を対象としてリダンダンシー（構造冗長性）評価の検討を行った．ここでリダンダンシーとは，橋梁の1部材もしくは一部が破断した場合における，橋梁全体系の余耐力を意味する．ケーススタディとして実際に斜材の破断が生じた木曽川大橋（単純下路トラス1960年設計）と，3径間連続上路トラス（1980年設計）を取り上げた．線形解析に基づくリダンダンシー評価を検討の基本としたが，別に行った橋梁全体の非線形解析結果と比較することで，線形リダンダンシー解析の妥当性を検証した．さらに格点部のみを詳細にモデル化した弾塑性解析を実施し，リダンダンシー解析における格点部の影響を検討した．最後に今回行ったリダンダンシー解析の結果を受けて，合理的な維持管理への提言をまとめた．The structural redundancy for steel truss bridges is investigated through the case studies for a simply supported steel truss bridge constructed in 1960 and a three-span continuous steel truss bridge designed as a standard model bridge in 1980. Here, the structural redundancy means the capability of a bridge to continue to carry loads after the failure of a member or a part of the bridge. To evaluate the redundancy, the linear structural analysis is employed as a standard procedure. The applicability of linear analysis to redundancy evaluation is examined by comparing with the nonlinear analysis results. In addition, detailed nonlinear FE analysis for a joint of truss bridge is carried out to check effect of a joint failure on the redundancy. Finally, on the basis of the study results, some recommendations toward rational bridge maintenance are presented.
土木学会, Japanese, Scientific journal
DOI：https://doi.org/10.2208/jsceja.65.410
DOI ID：10.2208/jsceja.65.410, ISSN：1880-6023, CiNii Articles ID：120001794167 - 合成I桁の正，負曲げ及び相関強度評価に関する一考察
長井正嗣; 稲葉尚文; 奥井義昭; 宮下剛; 平山繁幸; 細見直史
構造工学論文集, Volume：55A, First page：115, Last page：123, 2009
Benefit from LSD introduction is apparent for the design of steel-concrete composite girder bridges. In order to establish LSD, one of issues is to get a correct evaluation of ultimate strength in plastic region. So far, such evaluating formulae have been presented mainly from EC and AASHTO LRED. However, unresolved subjects to be improved or clarified have been seen, hence, several of them were clarified in this study based on experiment. Composite test girders were subjected to sagging or hogging flexure. Ultimate flexure strength of the girder under sagging flexure, in which plastic neutral axis is positioned in the slab, was examined. Ultimate coupled flexure/shear strength was also examined. Finally, the design procedure related to this study was summarized.
Japan Society of Civil Engineers, Scientific journal
DOI：https://doi.org/10.11532/structcivil.55A.115
DOI ID：10.11532/structcivil.55A.115, ISSN：1881-820X, CiNii Articles ID：130004950397 - 連続合成桁の負曲げ領域における横倒れ座屈設計法
奥井義昭; Bandula Heva, T; M; 小室雅人; 山口栄輝; 長井正嗣
構造工学論文集, Volume：54A, First page：58, Last page：67, 2008
In the current design procedure for recent continuous composite steel-concrete bridges at an internal support under negative bending moment, the lateral torsional buckling theory is applied to evaluate an allowable stress in disregard of lateral restraint of top flange by a concrete slab. In actual continuous composite bridges, instead of the lateral torsional buckling, restrained distortional buckling may occur. This paper proposes a design procedure for the restrained distortional buckling of continuous composite girders under negative bending moment.
土木学会, Japanese, Scientific journal
DOI ID：10.11532/structcivil.54A.58, ISSN：1881-6614, CiNii Articles ID：120004470172, CiNii Books ID：AA12210243 - Numerical simulation of the excavation damaged zone around an opening in brittle rock
A. Golshani; M. Oda; Y. Okui; T. Takemura; E. Munkhtogo
INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES, Volume：44, Number：6, First page：835, Last page：845, Sep. 2007, [Reviewed]
The micromechanics-based damage model proposed by Golshani et al. [A micromechanical model for brittle failure of rock and its relation to crack growth observed in triaxial compression tests of granite. Mech Mater 2006;38:287-303] is extended so that time-dependent behavior of brittle material can be taken into account, with special attention to the numerical analysis of an excavation damaged zone (EDZ) around an opening, which is a major concern in assessing the safety of underground repositories. The present model is capable of reproducing the three characteristic stages of creep behavior (i.e., primary, secondary, and tertiary creep) commonly observed in the laboratory creep tests. The sub-critical microcrack growth parameters (i.e., n and A) can be determined for Inada granite by fitting the numerical results of elapse time to failure versus the creep stress ratio curve with the experimental data under both dry and wet conditions. lt is found that moisture has a significant influence on the parameter A rather than the parameter n. Use of the extended model makes it possible to analyze not only the extension of microcrack length, but also the development of EDZ around an opening as a function of time. The damaged zones mainly develop in the sidewalls of the opening in the case that the vertical stress sigma(22) is larger than the horizontal stress sigma(11). (C) 2007 Elsevier Ltd. All rights reserved.
PERGAMON-ELSEVIER SCIENCE LTD, English, Scientific journal
DOI：https://doi.org/10.1016/j.ijrmms.2006.12.005
DOI ID：10.1016/j.ijrmms.2006.12.005, ISSN：1365-1609, Web of Science ID：WOS:000247163900003 - Effect of concrete crushing on flexural strength of steel-concrete composite girders
Vivek Kumar Gupta; Yoshiaki Okui; Naofumi Inaba; Masatsugu Nagai
Structural Engineering/Earthquake Engineering, Volume：24, Number：2, 2007, [Reviewed]
The ultimate flexural strength of composite steel girders with compact sections is examined through experimental investigation and elasto-plastic finite displacement analyses to develop a reduction factor of the ultimate flexural strength. A two-point loading test of a composite girder was carried out to verify the numerical modeling by comparing the experimental and numerical results. Then, a parametric study was performed using finite element analyses to investigate the effect of concrete crushing on the flexural strength of composite girders constructed using SM570 grade steel. Observations made by comparison of the ultimate flexural strength obtained from the experimental and numerical results with that according to the AASHTO and Eurocode show that the existing reduction factor equations are conservative and can be relaxed when the strength is controlled by crushing of concrete slab. A new reduction factor for the ultimate flexural strength for composite I-girders under positive bending is proposed.
English, Scientific journal
DOI：https://doi.org/10.2208/jsceseee.24.73s
DOI ID：10.2208/jsceseee.24.73s, ISSN：0289-8063, SCOPUS ID：36849048675 - Time-dependent damage growth and failure mechanism around tunnel under deep geological environments
Takemura, T; Golshani, A; Oda, M; Okui, Y; Takahashi, M
11th World Congress of the International society for rock mechanics, 2007
English, Research society - 二重合成桁橋における水平スタッ ドのせん断耐力に関する実験的研究
碇山晴久; 長井正嗣; 奥井義昭; 宮下 剛; 岩崎英治; 平山繁幸; 石川健一
第7回複合構造の活用に関するシンポジウム論文集, First page：20-1-20-8, Last page：1-20-8, 2007 - Effect of concrete crushing on flexural strength of steel-concrete composite girders
Vivek Kumar Gupta; Yoshiaki Okui; Naofumi Inaba; Masatsugu Nagai
Doboku Gakkai Ronbunshuu A, Volume：63, Number：3, First page：475, Last page：485, 2007
The ultimate flexural strength of composite steel girders with compact sections is examined through experimental investigation and elasto-plastic finite displacement analyses to develop a reduction factor of the ultimate flexural strength. A two-point loading test of a composite girder was carried out to verify the numerical modeling by comparing the experimental and numerical results. Then, a parametric study was performed using finite element analyses to investigate the effect of concrete crushing on the flexural strength of composite girders constructed using SM570 grade steel. Observations made by comparison of the ultimate flexural strength obtained from the experimental and numerical results with that according to the AASHTO and Eurocode show that the existing reduction factor equations are conservative and can be relaxed when the strength is controlled by crushing of concrete slab. A new reduction factor for the ultimate flexural strength for composite I-girders under positive bending is proposed.
土木学会, English, Scientific journal
DOI：https://doi.org/10.2208/jsceja.63.475
DOI ID：10.2208/jsceja.63.475, ISSN：1880-6023, CiNii Articles ID：80018159276, SCOPUS ID：79954449338 - Block FEM for time-dependent shear-lag behavior in two I-girder composite bridges
Yoshiaki Okui; Masatsugu Nagai
JOURNAL OF BRIDGE ENGINEERING, Volume：12, Number：1, First page：72, Last page：79, Jan. 2007
This paper presents a time-dependent finite-element analysis of a two I-girder composite bridge with a concrete slab. The creep and shrinkage of the concrete slab are considered as sources of time-dependent behavior. This analysis, unlike others, includes the shear-lag effect of the concrete slab on the time-dependent behavior of two I-girder bridges. An example calculation is given for a two-span continuous composite bridge with a cracking region in the concrete deck near the interior support. It is shown that the shear-lag effect becomes significant at the edge of the cracking region and at the bridge ends.
ASCE-AMER SOC CIVIL ENGINEERS, English, Scientific journal
DOI：https://doi.org/10.1061/(ASCE)1084-0702(2007)12:1(72)
DOI ID：10.1061/(ASCE)1084-0702(2007)12:1(72), ISSN：1084-0702, CiNii Articles ID：80018677281, Web of Science ID：WOS:000245204900009 - A micromechanical model for brittle failure of rock and its relation to crack growth observed in triaxial compression tests of granite
A Golshani; Y Okui; M Oda; T Takemura
MECHANICS OF MATERIALS, Volume：38, Number：4, First page：287, Last page：303, Apr. 2006
A micromechanics-based continuum damage model for brittle failure of rock is proposed to provide a numerical tool for analyzing not only the macro-scale mechanical responses of rock under compression such as strength, but also microscopic events, which take place in association with inelastic deformation. Special emphasis is placed on predicting numerically the changes in crack length and crack density during inelastic deformation terminating in brittle failure. Only two parameters, typical size and fracture toughness, are involved in the present model. These can be determined by reading the stress at an initial damage point C' on a stress-volumetric strain curve. The present model seriously underestimates the dilatational volumetric strains observed experimentally in triaxial tests of Inada granite. This is probably because a new micromechanism starts working in the final stage. The peak (failure) stress obtained numerically is in good accordance with the one observed in triaxial compression tests under a confining pressure higher than, say, 10 MPa. In the case of uniaxial tests in particular, the numerical model seriously overestimates the uniaxial strength. A major tension crack grows through the sample parallel to the axial direction in uniaxial tests, once the crack attains a critical length, while failure occurs in triaxial tests under confining pressures higher than 10 MPa only when the microcrack density is high enough. The overestimation probably reflects such a difference in the micromechanism leading to failure (peak stress). In spite of these difficulties, it can still be said that the proposed model has a chance of providing a sound basis for predicting crack growth, such as crack length and crack density, with sufficient accuracy. To improve the model, we must take into account the real micromechanism of crack growth effective in the final stage and the change in the number density of microcracks rho during the loading process. (C) 2005 Elsevier Ltd. All rights reserved.
ELSEVIER SCIENCE BV, English, Scientific journal
DOI：https://doi.org/10.1016/j.mechmat.2005.07.003
DOI ID：10.1016/j.mechmat.2005.07.003, ISSN：0167-6636, CiNii Articles ID：80017668158, Web of Science ID：WOS:000234949800002 - Development of web slenderness limits for composite I-girders accounting for initial bending moment
Vivek Kumar Gupta; Yoshiaki Okui; Masatsugu Nagai
Structural Engineering/Earthquake Engineering, Volume：23, Number：2, 2006, [Reviewed]
The positive bending moment capacity of composite steel girders is examined through parametric study employing elasto-plastic finite displacement analyses. The effects of initial bending moment on the bending moment capacity and on the web slenderness limit for section classification are investigated. Observations made during the numerical study indicate that the noncompact web slenderness limits in conventional design standards, which are based on tests of steel I-sections, are conservative for composite sections. Many sections, which are classified as slender by current specifications, demonstrate sufficient flexural capacity as noncompact. The conventional web slenderness limits for noncompact sections, independent of initial bending moment seems inappropriate for composite I-girders. The initial bending moment has considerable effect on the noncompact web slenderness limits. The web slenderness limits for compact and noncompact sections are proposed on the basis of the parametric study.
English, Scientific journal
DOI：https://doi.org/10.2208/jsceseee.23.229s
DOI ID：10.2208/jsceseee.23.229s, ISSN：0289-8063, SCOPUS ID：33847325387 - A micromechanical approach in modeling time- and stress-dependent failure of brittle rocks
Golshani, A; Okui, Y; Oda, M; Takemura, T
Mechanics of Materials, Volume：38, First page：287-303, 2006, [Reviewed]
English, Scientific journal - 連続合成桁のひび割れとケミカルプレストレスに関する実験的検討
木村 充; 長井正嗣; 細見雅生; 奥井義昭
構造工学論文集, Volume：52A, First page：039-1046, Last page：1046, 2006
土木学会, Scientific journal - Hyperelasticity model for finite element analysis of natural and high damping rubbers in compression and shear
AFMS Amin; SI Wiraguna; AR Bhuiyan; Y Okui
JOURNAL OF ENGINEERING MECHANICS-ASCE, Volume：132, Number：1, First page：54, Last page：64, Jan. 2006
Rate-independent monotonic behavior of filled natural rubber and high damping rubber is investigated in compression and shear regimes. Monotonic responses obtained from tests conducted in both regimes demonstrate the prominent existence of the Fletcher-Gent effect, indicated by high stiffness at low strain levels. An improved hyperelasticity model for compression and shear regimes is proposed to represent the rate-independent instantaneous and equilibrium responses including the Fletcher-Gent effect. A parameter identification scheme involving simultaneous minimization of least-square residuals of uniaxial compression and simple shear data is delineated. The difficulties of identifying a unique set of hyperelasticity parameters that hold for both compression and shear deformation modes are thus overcome. The proposed hyperelasticity model has been implemented in a general purpose finite element program. Finite element simulations of experiments have shown the adequacy of the proposed hyperelasticity model, estimated parameters, and employed numerical procedures. Finally, numerical experiments were conducted to further explore the potential of the proposed model, and estimated parameters in analyzing rubber layers of a base isolation bearing subjected either to compression or to a combination of compression and shear.
ASCE-AMER SOC CIVIL ENGINEERS, English, Scientific journal
DOI：https://doi.org/10.1061/(ASCE)0733-9399(2006)132:1(54)
DOI ID：10.1061/(ASCE)0733-9399(2006)132:1(54), ISSN：0733-9399, CiNii Articles ID：80017686150, Web of Science ID：WOS:000234377700006 - Development of web slenderness limits for composite i-girders accounting for initial bending moment
Vivek Kumar Gupta; Yoshiaki Okui; Masatsugu Nagai
Doboku Gakkai Ronbunshuu A, Volume：62, Number：4, First page：854, Last page：864, 2006
The positive bending moment capacity of composite steel girders is examined through parametric study employing elasto-plastic finite displacement analyses. The effects of initial bending moment on the bending moment capacity and on the web slenderness limit for section classification are investigated. Observations made during the numerical study indicate that the noncompact web slenderness limits in conventional design standards, which are based on tests of steel I-sections, are conservative for composite sections. Many sections, which are classified as slender by cuffent specifications, demonstrate sufficient flexural capacity as noncompact. The conventional web slenderness limits for noncompact sections, independent of initial bending moment seems inappropriate for composite I-girders. The initial bending moment has considerable effect on the noncompact web slenderness limits. The web slenderness limits for compact and noncompact sections are proposed on the basis of the parametric study.
English, Scientific journal
DOI：https://doi.org/10.2208/jsceja.62.854
DOI ID：10.2208/jsceja.62.854, ISSN：1880-6023, SCOPUS ID：36849073991 - Nonlinear dependence of viscosity in modeling the rate-dependent response of natural and high damping rubbers in compression and shear: Experimental identification and numerical verification
AFMS Amin; A Lion; S Sekita; Y Okui
INTERNATIONAL JOURNAL OF PLASTICITY, Volume：22, Number：9, First page：1610, Last page：1657, 2006, [Reviewed]
The rate-dependent behavior of filled natural rubber (NR) and high damping rubber (HDR) is investigated in compression and shear regimes. In order to describe the viscosity-induced rate-dependent effects, a constitutive model of finite strain viscoelasticity founded on the basis of the multiplicative decomposition of the deformation gradient tensor into elastic and inelastic parts is proposed. The total stress is decomposed into an equilibrium stress and a viscosity-induced overstress by following the concept of the Zener model. To identify the constitutive equation for the viscosity from direct experimental observations, an analytical scheme that ascertains the fundamental relation between the inelastic strain rate and the overstress tensor of the Mandel type by evaluating simple relaxation test results is proposed. Evaluation of the experimental results using the proposed analytical scheme confirms the necessity of considering both the current overstress and the current deformation as variables to describe the evolution of the rate-dependent phenomena. Based on this experimentally based motivation, an evolution equation using power laws is proposed to represent the effects of internal variables on viscosity phenomena. the proposed evolution equation has been incorporated in the finite strain viscoelasticity model in a thermodynamically consistent way. Simulation results for simple relaxation tests, multi-step relaxation tests and monotonic tests at different strain rates using the developed model show an encouraging correlation with the experiments conducted on HDR and NR in both compression and shear regimes. Finally, an approach to extend the proposed evolution equation for rate-dependent cyclic processes is proposed. The simulation results are critically compared with the experiments. (C) 2005 Elsevier Ltd. All rights reserved.
PERGAMON-ELSEVIER SCIENCE LTD, English, Scientific journal
DOI：https://doi.org/10.1016/j.ijplas.2005.09.005
DOI ID：10.1016/j.ijplas.2005.09.005, ISSN：0749-6419, CiNii Articles ID：120001370476, Web of Science ID：WOS:000238583700003 - Some topics of studies for steel-concrete composite girders
Okui Y. and Gupta V.K.
Proc. of 8th Korea-China-Japan Symposium on steel structure, Seoul, 2005 - Analytical study on steel-concrete composite girders
Okui Y.,
Proc. of Japan-Bangladesh Joint Seminar on Advances in Bridge Engineering, Dhaka, Bangladesh, First page：113, Last page：124, 2005 - Hydraulic behaviour of Inada granite in the excavation disturbed zone around underground openings
Golshani, A., Okui, Y., Oda, M., Takemura, T.
Proceedings of the Seventh International Summer Symposium, JSCE, Tokyo, First page：153, Last page：156, 2005 - Proceedings of the Japan-Bangladesh Joint SEminar on Advances in Bridges Eng.
Amin, A.F.M.S, Okui, Y., Safiullah, A.M.M editors
The instituton of Engineers, Bangladsh, First page：168, 2005 - Load-carrying capacity of composite girders in cable-stayed bridges
Okui Y., Nagai M., Iwasaki E. and Hirono T.
4th European conference on steel and composite structures, Eurosteel 2005, Maastricht, Netherlands, First page：4.6.7, Last page：12, 2005 - 連続合成桁のひび割れ幅算定のための床版有効幅推定式の提案
奥井義昭; 本田卓士; セントラルコンサルタンツ; Khan, Q; niversity of Engineering; Technology Taxila; 長井正嗣; 長岡技術科
土木学会論文集, Volume：I-70780, Number：780, First page：155, Last page：163, 2005
An effective width formula for crack width evaluation in negative bending moment regions near internal supports of continuous composite girder bridges is proposed. The formula takes account of shear-lag effect and includes cracking effect in concrete slabs of composite bridges. A parametric study of 3D nonlinear FE analyses for composite bridges with span lengths ranging from 30 to 60 m are carried out to develop the formula. Since the effective width varies depending on the strain level of concrete slabs due to nonlinear effects, a modification equation of the effective width is proposed as well.
Japan Society of Civil Engineers, Japanese, Scientific journal
DOI ID：10.2208/jscej.2005.780_155, ISSN：0289-7806, CiNii Articles ID：10013712696, CiNii Books ID：AN10014020 - 合成桁の終局曲げ強度特性に関する研究
稲葉 尚文; 奥井 義昭; 長井 正嗣
第26回日本道路会議論文集, First page：14026, 2005 - Time dependent continuous damage model for brittle failure of rocks
Golshani, A; Okui, Y; Takemura, T; Oda, M
Proceedings of the International society for rock mechanics Regional symposium EUROCK 2004 & 53th Geomechanics Colloquy,, First page：701-706, Last page：706, 2004, [Reviewed]
English, Research society - High Damping Rubber for Base Isolation Bearing: Mechanical Behavior and Constitutive Modeling
Amin; A.F.M.S; Bangladesh University of Engineering; Technology; Okui, Y
Filler Reinforcement of Rubbr, First page：51, Last page：57, 2004 - 連続合成桁の初期ひび割れ状態を考慮したひび割れ幅, 鉄筋応力算定法の一提案
長井正嗣; 長岡技術科; 奥井義昭; 岩崎英治
土木学会論文集, Volume：I-67759, Number：759, First page：283, Last page：292, 2004
In recent years, methods of evaluating the crack width in concrete slabs and those of the stress in reinforcing bars at intermediate supports in continuous composite bridges have been proposed. They are applicable to evaluation of the crack width and stress in reinforcing bars at the stabilized crack state (fully cracked state). In many actual bridges, however, the initial crack state has been observed under the hogging bending moment. In this paper, employing formulas recommended in a current method and CEB/FIP-90, a method of evaluating the crack width and stress in reinforcing bars is proposed, in which the crack width and stress in reinforcing bars for both initial and stabilized crack states can be dealt with.
Japan Society of Civil Engineers, Japanese, Scientific journal
DOI ID：10.2208/jscej.2004.759_283, ISSN：0289-7806, CiNii Articles ID：10012033501, CiNii Books ID：AN10014020 - 湾岸地域における複合構造橋梁の実用化に関する調査研究
依田,奥井
JSSCテクニカルレポ-ト58, First page：1, Last page：227, 2004
(社)日本鋼構造協会 - 高架橋の動的非線形解析における感度分析と部分構造モデルの妥当性の検討
奥井義昭
構造工学論文集, Volume：50A, First page：1419, Last page：1426, 2004
土木学会, Scientific journal - 合成斜張橋主桁の終局挙動の解明と安定照査法
長井正嗣; 長岡技術科; 奥井義昭; 野上邦栄; 東京都立大; 廣野智紀
構造工学論文集, Volume：50A, First page：53, Last page：59, 2004
土木学会, Scientific journal - Fragility analysis of a bridge substructure under Level-1 earthquake and its application to determination of safety factors
Hoque, M; Seshimo, Y; Tokyo Electric power Service; Tunekuni, M; Okui, Y; Sugiyama; Yamanashi University), T
J. Struct. Eng., JSCE, Volume：50A, First page：257, Last page：268, 2004
Scientific journal - Measurement of lateral deformation in natural and high damping rubbers in large deformation uniaxial tests
AFMS Amin; MS Alam; Y Okui
JOURNAL OF TESTING AND EVALUATION, Volume：31, Number：6, First page：524, Last page：532, Nov. 2003, [Reviewed]
In testing the mechanical behavior of rubbers, the incompressibility assumption is used to predict the deformed cross section under loading and thereby to calculate the true stress. There are, however, cases where rubbers can undergo considerable volumetric deformation in large strain experiments. Microstructural investigation through a scanning electron microscope was carried out on a void-filled natural rubber specimen to clarify the effect of voids on the compressibility feature. The microstructure of the natural rubber was observed qualitatively and quantitatively in uniaxial tension and compared to the microstructure in the undeformed condition. The existence of the compressibility feature in the void-filled rubber was confirmed from a microstructural viewpoint. The findings indicate the necessity of accurate measurement of the deformed cross section in mechanical tests to obtain the true stress. To this end, an experimental setup capable of measuring the deformed cross section of the rubber specimens subjected to large uniaxial compression is proposed. To do this, the accuracy of laser beams is used for measurement of distance and a mechanical jig is developed to synchronize the movement of the laser transducer with the vertical crosshead of the load cell of a computer-controlled servohydraulic testing machine. Thus the constraints associated with conventional strain gages in measuring large strains are overcome. Finally, two natural rubber specimens and one high damping rubber specimen were tested in the proposed setup to display the adequacy of the developed device in measuring lateral deformation of rubber-like highly deformable solids in large strain uniaxial testing.
AMER SOC TESTING MATERIALS, English, Scientific journal
ISSN：0090-3973, Web of Science ID：WOS:000186516200010 - Micromechanics-based prediction of creep failure of hard rock for long-term safety of high-level radioactive waste disposal system
K Miura; Y Okui; H Horii
MECHANICS OF MATERIALS, Volume：35, Number：3-6, First page：587, Last page：601, Mar. 2003, [Reviewed]
A high-level radioactive waste disposal project is under way in Japan. Isolation of the radioactive waste in a rock formation at great depth is considered as one of the promising disposal methods, Before proceeding with the disposal project, however, assessment of the long-term stability of rock mass surrounding waste packages is necessary. This paper presents a micromechanics-based model for predicting the creep failure of hard rock under compression. The subcritical crack growth due to stress corrosion cracking and interaction effects between cracks are considered as the main mechanisms of creep failure. An evolution problem of two interacting cracks is formulated and creep failure following tertiary creep is represented as unstable extension of the interacting cracks in the present model. The time to failure is calculated for different values of axial stress, confining pressure, and environmental conditions such as temperature and presence of water. The effects of water, temperature. and stress states on the long-term behavior are also included in the proposed model. (C) 2002 Elsevier Science Ltd. All rights reserved.
ELSEVIER SCIENCE BV, English, Scientific journal
ISSN：0167-6636, Web of Science ID：WOS:000180597600028 - A method for crack width evaluation of continuous composite girder bridges accounting for shear-lag effect
Qaiser-Uz-Zaman Khan; Takuji Honda; Yoshiaki Okui; Masatsugu Nagai
Structural Engineering/Earthquake Engineering, Volume：20, Number：2, 2003, [Reviewed]
A numerical procedure for crack width evaluation of steel-concrete composite girder bridges under negative bending moment is proposed. The procedure is combination of 3-dimensional finite element (FE) analysis with smeared crack model and a bond-slip differential equation. From the FE analysis, the averaged behaviour including shear-lag as well as cracking is calculated. Then, the crack width is evaluated by using the differential equation and the FE results. Attention is paid to the consistency between the FE modelling and the employed bond-slip differential equation. The obtained crack widths are shown to compare well with those from experiments on composite girder specimens.
Japan Society of Civil Engineers, English, Scientific journal
DOI：https://doi.org/10.2208/jsceseee.20.131s
DOI ID：10.2208/jsceseee.20.131s, ISSN：0289-8063, SCOPUS ID：1842430095 - A microcrack-based constitutive model for brittle geomaterials
A Golshani; Y Okui; T Takemura; M Oda; K Suzuki
ROCK STRESS, First page：219, Last page：224, 2003, [Reviewed]
A micromechanical continuum model based on mechanics of tensile microcracks, is presented for brittle failure of rock containing randomly distributed microcracks. The proposed model describes both the mechanical response of rock and microcracks geometry evolution under compression. By generalizing the results obtained from the analysis of one single microcrack and including the effects of interaction among neighboring microcracks, this model for brittle rock under compression is derived. In order to illustrate the predictive capability of the proposed model for mechanical properties of rock and microcracks geometry evolution under compression, the model is applied to Inada granite. Numerical results are compared with experimental data from triaxial compression tests and microscopic observations of microcracks on Inada granite. The predicted strength for Inada granite of proposed model is in good agreement with experimental data. Moreover, microcracks geometry evolution is correctly described by this model.
A A BALKEMA PUBLISHERS, English, International conference proceedings
Web of Science ID：WOS:000189130200024 - COMPARATIVE STUDY ON CRACK WIDTH EVALUATION METHODS FOR CONTINUOUS COMPOSITE GIRDERS
NAGAI Masatsugu; OKUI Yoshiaki; IWASAKI Eiji
Doboku Gakkai Ronbunshu, Volume：710, First page：427, Last page：437, Jul. 2002
Recent design codes for continuous composite girder bridges allow tensile cracking in a concrete slab near intermediate supports. To ensure durability of the concrete slab, introduced crack width has to be limited within an allowable limit, and accordingly it becomes important to predict crack width under a service load. In this paper, crack width evaluation methods for steel-concrete composite girder under negative bending moment are compared to investigate differences in those mechanical background and evaluated results. Inconsistency in application of conventional methods is pointed out.
Japan Society of Civil Engineers, Japanese
DOI：https://doi.org/10.2208/jscej.2002.710_427
DOI ID：10.2208/jscej.2002.710_427, ISSN：0289-7806, CiNii Articles ID：10009264847, CiNii Books ID：AN10014020 - An improved hyperelasticity relation in modeling viscoelasticity response of natural and high damping rubbers in compression: experiments, parameter identification and numerical verification
AFMS Amin; MS Alam; Y Okui
MECHANICS OF MATERIALS, Volume：34, Number：2, First page：75, Last page：95, Feb. 2002
The rate-dependent behavior of natural and high damping rubbers is investigated in the compression regime. The experimental results demonstrate the prominence of the rate-dependent high initial stiffness feature in high damping rubber at low stretch level. A modified hyperelastic model is proposed to represent the rate-independent elastic responses including the high initial stiffness feature. A comparative evaluation is carried out to display the better performance of the proposed hyperelastic model than conventional ones over the strain range in representing the equilibrium and the instantaneous responses. The hyperelastic model is incorporated in a finite deformation rate-dependent model structure. A parameter identification scheme is proposed to identify the parameters for the equilibrium and instantaneous responses from the experimental data. The difficulties of direct application of infinitely fast or slow loading rate to such highly viscous materials to obtain these responses and thereby to identify the nonlinear elastic parameters are overcome. The proposed scheme is applied to three types of specimens including natural rubber and high damping rubber. Finally, numerical results obtained from the finite deformation rate-dependent model are compared with the test results to verify the adequacy and robustness of the proposed parameter identification scheme. (C) 2002 Elsevier Science Ltd. All rights reserved.
ELSEVIER SCIENCE BV, English, Scientific journal
DOI：https://doi.org/10.1016/S0167-6636(01)00102-8
DOI ID：10.1016/S0167-6636(01)00102-8, ISSN：0167-6636, CiNii Articles ID：80012870216, Web of Science ID：WOS:000174202300001 - EX-plication of micromechanics to modeling compressive failure of rock
Y Okui; H Horii
MATERIALS SCIENCE RESEARCH INTERNATIONAL, Volume：6, Number：2, First page：65, Last page：73, Jun. 2000
This article presents a review of the research work related to the micromechanical modeling of behavior of hard rock under compression. To this end, it initially provides observed macroscopic behavior of compressive rock for both time-independent and -dependent cases. It proceeds with a review of microscopic observations of rock failure including recent techniques in rock experiments. Crack growth laws in rock for both short- and long-term loading axe next reviewed. Finally, micromechanical models employed in literatures and associated continuum theories based on micromechanics axe introduced.
SOC MATERIALS SCIENCE, JAPAN, English, Scientific journal
DOI：https://doi.org/10.2472/jsms.49.6Appendix_65
DOI ID：10.2472/jsms.49.6Appendix_65, ISSN：1341-1683, Web of Science ID：WOS:000175672100001 - 鋼橋技術研究会設計部会報告書
奥井他,33名
First page：2015, 2000 - Mechanism of microcracking localization of compressive rocks: Anisotropic interaction between microcracks
Y Okui; H Horii
LOCALIZATION AND BIFURCATION THEORY FOR SOILS AND ROCKS, First page：143, Last page：151, 1998, [Reviewed]
Mechanisms of the time-dependent and -independent localization of hard rock under compression are investigated by considering an evolution problem of a system of microcracks. The stress-corrosion cracking is considered as a main source of time-dependent crack growth. For time-independent crack growth, Griffith criterion is employed as a crack extension law. The numerical results of the evolution problem suggest that the anisotropic interaction between microcracks is the main mechanism of microcracking localization. This evolution problem for the system of discrete microcracks is homogenized into a continuum model, in which microcracks are assumed to be distributed continuously in an elastic body. By using standard procedure of micromechanics, a stress-strain relationship for the homogenized continuum is derived. The evolution equation of microcracks along with this stress-strain relationship serves as a constitutive relationship. When formulating the evolution equation, a new field variable is introduced in order to maintain the anisotropic interaction effect among microcracks, and an integral equation for the new variable is also formulated. This integral equation brings about nonlocality into the constitutive relationship. In the numerical analysis of the continuum model, compressive strengths of rock are tried to be predicted.
A A BALKEMA PUBLISHERS, English, International conference proceedings
Web of Science ID：WOS:000078033200016 - 合成箱桁を主桁とする斜張橋の力学特性と適用スパンに関する研究
構造工学論文集, Volume：44A, First page：1171, Last page：1179, 1998
土木学会, Scientific journal - Stress and time-dependent failure of brittle rocks under compression: A theoretical prediction
Y Okui; H Horii
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, Volume：102, Number：B7, First page：14869, Last page：14881, Jul. 1997, [Reviewed]
A micromechanics-based continuum theory called interaction field theory (IFT) can reproduce localization phenomena such as shear faulting and axial splitting of rock under compression. The validity of IFT is examined by comparing its predictions of shortterm strength and creep behavior of hard rock with reported experimental data. The theory is formulated through an averaging scheme for an elastic solid containing many microcracks. The growth of the microcracks is assumed to occur through two mechanisms: stress-induced crack growth and stress corrosion. Failure of rock under compression is known to be governed by the interactive behavior of microcracks. Yet in many earlier analyses the information on interaction is lost through conventional averaging schemes. IFT introduces a new field quantity which represents the interaction effect and the associated governing integral equation. IFT reproduces not only inelastic deformation of rock but also eventual macroscopic failure due to localization of microcracking. In the numerical analysis of short-term behavior, macroscopic failure is reproduced as a bifurcation from a homogeneous state of deformation into a localized one. The strengths are obtained as a result of numerical analysis with material constants of an intact matrix and the quantities related to initial defects. The strengths of Westerly granite obtained as a function of the confining pressure are compared with published experimental data. For time-dependent behavior of hard rock, creep tests of granite are analyzed. Comparisons are made between experimental failure times and numerical results for different confining pressures and environmental conditions.
AMER GEOPHYSICAL UNION, English, Scientific journal
ISSN：2169-9313, eISSN：2169-9356, Web of Science ID：WOS:A1997XJ83100010 - Stress and Time-Dependent Failure of Brittle Rocks under Compression:a Theoretical Predection
OKUI Y; HORII H
Journal of Geophysical Research, Volume：102, Number：B7, First page：14869, Last page：14881, 1997
Scientific journal
DOI：https://doi.org/10.1029/97JB00476
DOI ID：10.1029/97JB00476, ISSN：0148-0227, CiNii Articles ID：30013336745 - MICROMECHANICS-BASED CONTINUUM THEORY AND NUMERICAL-ANALYSIS OF LOCALIZATION PHENOMENA
H HORII; Y OKUI
COMPUTER METHODS AND ADVANCES IN GEOMECHANICS, VOL 2, First page：1687, Last page：1692, 1994, [Reviewed]
A A BALKEMA, English, International conference proceedings
Web of Science ID：WOS:A1994BB12T00128 - A CONTINUUM THEORY FOR SOLIDS CONTAINING MICRODEFECTS
Y OKUI; H HORII; N AKIYAMA
INTERNATIONAL JOURNAL OF ENGINEERING SCIENCE, Volume：31, Number：5, First page：735, Last page：749, May 1993
The conventional continuum theory is based on the constitutive equations that prescribe relations between the average stress and strain, valid when the local deformation is more or less uniform. However, when the deformation is localized, the effects of interaction among microdefects become important, and must be included in the formulation of any effective continuum theory. One promising way of establishing a continuum theory that can capture localization phenomena, is to use micromechanics. In this study, we establish a micromechanics-based continuum theory (named interaction field theory) which can model localization phenomena, such as shear failure in rocks or shear band formation in sands under compression. A new field variable (interaction field) that characterizes the effects of interaction among microdefects is introduced, and its governing integral equation is formulated. Although the technique is applicable to any material with any microstructure, for an illustration the theory is formulated and used to study the behavior of rocks under compression. Numerical results are given that illustrate the difference between the proposed theory and the conventional continuum damage mechanics. It is confirmed that the proposed theory can describe the localization process by microcracking in shear failure and axial splitting of rocks under compression.
PERGAMON-ELSEVIER SCIENCE LTD, English, Scientific journal
DOI：https://doi.org/10.1016/0020-7225(93)90121-A
DOI ID：10.1016/0020-7225(93)90121-A, ISSN：0020-7225, CiNii Articles ID：80006991839, Web of Science ID：WOS:A1993KW58100004 - A MICROMECHANICS-BASED CONTINUUM THEORY FOR STRAIN LOCALIZATION AND SOFTENING UNDER COMPRESSION
Y OKUI; H HORII; N AKIYAMA
FRACTURE MECHANICS OF CONCRETE STRUCTURES /, First page：275, Last page：280, 1992, [Reviewed]
ELSEVIER APPL SCI PUBL LTD, English, International conference proceedings
Web of Science ID：WOS:A1992BX45N00029 - Evaluation of bending moment due to geometrical nonlinearity in main girder of cable-stayed bridges.
NAGAI Masatugu; AKAO Hiroshi; SANO Shin-ichiro; OKUI Yoshiaki
Doboku Gakkai Ronbunshu, Volume：1988, Number：392, First page：307, Last page：316, 1988
Bending moment due to geometrical nonlinearity in a main girder should be checked on designing cable-stayed girder bridges. Even though the employment of nonlinear analysis by an electronic computer is powerful, much time is also inevitable for carrying it out.
In this paper, a formula to estimate the bending moment due to nonlinearity is proposed and also dominant parameters which have a close relation to nonlinear behavior of the girder are summarized. This simple formula is useful for designers' judgement whether nonlinear effect should be taken into account or not beforehand. In addition, it is available for selecting a bending rigidity of the girder of long-spanned cable-stayed girder bridges at preliminary design stage.
Japan Society of Civil Engineers, Japanese
DOI：https://doi.org/10.2208/jscej.1988.392_307
DOI ID：10.2208/jscej.1988.392_307, ISSN：0289-7806, CiNii Articles ID：130003799573, CiNii Books ID：AN10014020
- 鋼橋の設計・評価技術の高度化
鋼橋の強靱化・長寿命化研究委員会,合理化設計研究部会 奥井他
（一社）日本鋼構造協会，テクニカルレポート, Volume：No.114, Number：114, 2018
J-Global ID：201902272562961863 - Next Step Direction of Steel Bridge Design
奥井義昭
橋梁と基礎, Volume：49, Number：8, First page：44, Last page：47, Aug. 2015
Japanese
ISSN：0287-170X, CiNii Articles ID：40020547106, CiNii Books ID：AN00062923 - 免震橋の水平2方向耐震性能に関する漸増動的解析
党紀; 蛯沢佑紀; 五十嵐晃; 奥井義昭
Volume：69, Number：I-058, First page：115, Last page：116, 10 Sep. 2014
大阪大学，9/10-12
Japanese, Summary national conference - Probabilistic local buckling strength analysis of compressive platesfor normal and bridge high performance steels
Y. Okui; M. Komuro; D. DUC Vlet
37th IABSE Symposium Madrid 2014, Volume：102, First page：1157, Last page：1163, Sep. 2014, [Reviewed]
International Association for Bridge and Structural Engineering, English
DOI：https://doi.org/10.2749/222137814814067392
DOI ID：10.2749/222137814814067392 - Recent topics of Japanese design codes for steel and composite bridges
Okui, Y
First page：9, Last page：14, 2009 - Development of Rheology model for RBs and LRBs and its implementation in seismic analysis
Razzaq, M.K; Bhuiyan, A.R; Okui, Y; Mitamura, H; Imai,T
First page：21, Last page：24, 2009 - Elasto-plastic behavior and ultimate strength of 200-meters cable-stayed composite girder bridge with low tower
Shintarou Io; Kuniei Nogami; Yoshiaki Okui; Yasuyuki Morizono
2009 - A case study for after fracture redundancy analysis of a turss bridge in Japan
Yoshiaki Okui; Hideki Nagatani; Naomitsu Akashi; Takenori Matsuda; Masahiro Yasuda; Hironori Ishii; Masayuki Miyamori; Yasuhiro Obata; Hiroshi Hirayama
First page：87, Last page：92, 2009 - Recent topics of Japanese design codes for steel and composite bridges
Okui, Y
Proceedings of the 10th Korea-China-Japan Symposium on Structural Steel Construction, First page：9, Last page：14, 2009 - Development of Rheology model for RBs and LRBs and its implementation in seismic analysis
Razzaq, M.K; Bhuiyan, A.R; Okui, Y; Mitamura, H; Imai,T
Proc. of 11th International summer symposium conference organized by Japan Society of Civil Engineers, First page：21, Last page：24, 2009 - Elasto-plastic behavior and ultimate strength of 200-meters cable-stayed composite girder bridge with low tower
Shintarou Io; Kuniei Nogami; Yoshiaki Okui; Yasuyuki Morizono
Proc. of the 10th Japan-Korea joint Symposium on steel bridges, Volume：10, 2009 - A case study for after fracture redundancy analysis of a turss bridge in Japan
Yoshiaki Okui; Hideki Nagatani; Naomitsu Akashi; Takenori Matsuda; Masahiro Yasuda; Hironori Ishii; Masayuki Miyamori; Yasuhiro Obata; Hiroshi Hirayama
Proc. of Australia-Japan workshop on steel and composite structures, First page：87, Last page：92, 2009 - Revisit of section classification requirements for composite girders under positive flexure
Okui, Y; Gupta, V.K; Nagai, M
Volume：A, First page：381, Last page：386, 2008 - A design method of continuous composite girders under negative bending moment against restrained distortional buckling
Okui, Y; Bandula Heva T.M; Komuro, M; Nagai, M
First page：1, Last page：7, 2008 - Nonlinear viscosity law for rate-dependent response of high damping rubber: FE implementation and verification
A. R. Bhuiyan; A. Em. S. Amin; T. Hossain; Y. Okui
CONSTITUTIVE MODELS FOR RUBBER V, First page：279, Last page：+, 2008
A simple computational strategy for implementation of a finite strain viscohyperelasticity model in a standard FEM code is discussed. To this end, a recently published evolution law that takes the nonlinear dependence of viscosity into account is considered. Such a law considers the maximum overstress experienced in past history and deformation as the internal variables. In order to simulate the stress-response for a particular boundary value problem, an analytical solution scheme using the Bernoulli's principle has been applied to derive the stress expressions. The expressions have been incorporated in a finite element code. Limited numerical trials show the applicability of the procedure for simulating rate dependent responses obtained from one dimensional experiments e.g. uniaxial compression or simple shear tests on natural rubber and high damping rubber specimens. The limitations of this approach for solving an arbitrary boundary value problem are also discussed.
TAYLOR & FRANCIS LTD, English
Web of Science ID：WOS:000251796000042 - Revisit of section classification requirements for composite girders under positive flexure
Okui, Y; Gupta, V.K; Nagai, M
Eurosteel 2008: 5th European Conference on Steel and Composite Structures, Ofner, R., Beg, D., Dink, J., Greiner, R., Unterweger H., (eds.), Volume：A, First page：381, Last page：386, 2008
ECCS European Convention for Construction Steelwork - A design method of continuous composite girders under negative bending moment against restrained distortional buckling
Okui, Y; Bandula Heva T.M; Komuro, M; Nagai, M
Eleventh East Asia-Pacific Conference on Structural Engineering & Construction (EASEC-11) "Building a sustainable environment", First page：1, Last page：7, 2008 - 連続合成桁中間支点部の横座屈に対する合理的な設計方法の開発とその検証
奥井 義昭
総合研究機構研究プロジェクト研究成果報告書, Number：5(18年度), First page：626, Last page：627, 2007
埼玉大学総合研究機構 - Web Slenderness Limit for Section Classification of Unshored Composite Girders
Okui, Y; Gupta, V.K; Nagai, M
2007 - Experimental study on ultimate strength of composite and double-composite girders
Nagai, M; Inaba, N; Tomita, Y; Okui, Y
Volume：2, First page：329, Last page：334, 2007 - Experimental Study on Shear Strength of Lying Stud in Double-Composite Girder Bridges
Nagai, M; Okui, Y; Miyashita, T; Iwasaki, E; Ikariyama H; Kenichi ISHIKAWA; Shigeyuki HIRAYAMA
2007 - Design issues for steel-concrete composite girders
Okui, Y
First page：85, Last page：93, 2007 - 連続合成桁中間支点部の横座屈に対する合理的な設計方法の開発とその検証
奥井 義昭
総合研究機構研究プロジェクト研究成果報告書, Number：5(18年度), First page：626, Last page：627, 2007 - Web Slenderness Limit for Section Classification of Unshored Composite Girders
Okui, Y; Gupta, V.K; Nagai, M
Proc. of The 7th German-Japanese Bridge Symposium, 2007 - Nonlinear viscosity law for rate-dependent response of high damping rubber: EF implementation and verification
Bhuiyan, A.R; Amin, A; Hossan, T; Okui, Y
Proc. of the 5th European Conference on Constitutive Models for Rubber, ECCMR, First page：279, Last page：284, 2007 - Experimental study on ultimate strength of composite and double-composite girders
Nagai, M; Inaba, N; Tomita, Y; Okui, Y
Proc. of 8th Pacific Structural Steel Conference, Volume：2, First page：329, Last page：334, 2007 - Experimental Study on Shear Strength of Lying Stud in Double-Composite Girder Bridges
Nagai, M; Okui, Y; Miyashita, T; Iwasaki, E; Ikariyama H; Kenichi ISHIKAWA; Shigeyuki HIRAYAMA
Proc. of The 7th German-Japanese Bridge Symposium, 2007 - Design issues for steel-concrete composite girders
Okui, Y
Proc. of China-Japan Joint Seminar on Steel and Composite Bridges, First page：85, Last page：93, 2007 - Numerical simulation of an excavation disturbed zonearound a tunnel in brittle rock<速報>
小田 匡寛奥井
Volume：39, First page：110, Last page：113, 2006
The micromechanics-based damage model proposed by Golshani et al. (2005) is extended so that time-dependent behavior of brittle material can be taken into account, with special attention to the numerical analysis of an excavation damage zone (EDZ) around a tunnel, which is a major concern in assessing the safety of underground repositories. The present model is capable of reproducing the three characteristic stages of creep behavior (i.e., primary, secondary and tertiary creep) commonly observed in laboratory creep tests. Using the present model, sub-critical microcrack growth parameters (i.e. n and A) can be determined for Inada granite by fitting the numerical results of elapse time to failure versus the creep stress ratio curve with the experimental data under both dry and wet conditions. It is found that moisture has a significant influence on the parameter A rather than the parameter n. Use of the extended model makes it possible to analyze not only the extension of microcrack length, but also the development of the excavation damage zone (EDZ) around tunnels as a function of time. The disturbed zones mainly develop in the sidewalls of the tunnel in the case that the vertical stress is larger than the horizontal stress.
English
ISSN：1880-4446, CiNii Articles ID：120001370434 - 勝鬨橋の再跳開技術に関する調査研究報告書
藤野陽三,奥井義昭
2006
土木学会 - 合成桁による設計思想の転換
奥井義昭
Volume：40, First page：64, Last page：67, 2006 - 高減衰ゴムのマイクロメカニクスに基づく構成則モデルと破壊予測手法の開発
奥井 義昭
総合研究機構研究プロジェクト研究成果報告書, Number：4(17年度), 2006
埼玉大学総合研究機構 - 鋼連続合成桁橋の構造合理化に関する技術検討業務報告書
長井正嗣,奥井義昭
2006
（財）高速道路技術センター - 鋼合成構造標準示方書の説明
奥井義昭
第11回鋼構造基礎講座「合成構造の設計と事例紹介」テキスト, 2006
土木学会 - 硬岩の長期劣化予測を目的とした微視情報も算出可能な連続体理論の構築とその検証
奥井義昭,小田匡寛
科学研究補助金研究成果報告書, 2006 - Ultimate Strength of Composite I-Girder in Pure Positive Bending
Nagai, M; Okui, Y; Inaba, N
First page：ID-030-1-10, 2006 - FE Analysis with Smeared Crack Model for Crack Width Evaluation in Continuous Composite Girders
Okui, Y; Honda, Y; Khan, Q.Z; Nagai M
First page：ID-034-1-7, 2006 - Effect of Initial Bending Moment in Composite Girder under Flexure for Unshored Construction
Gupta, V.K; Okui, Y; Nagai, M
First page：ID-047-1-8, 2006 - Numerical simulation of an excavation disturbed zonearound a tunnel in brittle rock<速報>
小田 匡寛奥井
埼玉大学紀要, 工学部, 第1部論文集, Volume：39, First page：110, Last page：113, 2006
The micromechanics-based damage model proposed by Golshani et al. (2005) is extended so that time-dependent behavior of brittle material can be taken into account, with special attention to the numerical analysis of an excavation damage zone (EDZ) around a tunnel, which is a major concern in assessing the safety of underground repositories. The present model is capable of reproducing the three characteristic stages of creep behavior (i.e., primary, secondary and tertiary creep) commonly observed in laboratory creep tests. Using the present model, sub-critical microcrack growth parameters (i.e. n and A) can be determined for Inada granite by fitting the numerical results of elapse time to failure versus the creep stress ratio curve with the experimental data under both dry and wet conditions. It is found that moisture has a significant influence on the parameter A rather than the parameter n. Use of the extended model makes it possible to analyze not only the extension of microcrack length, but also the development of the excavation damage zone (EDZ) around tunnels as a function of time. The disturbed zones mainly develop in the sidewalls of the tunnel in the case that the vertical stress is larger than the horizontal stress.
埼玉大学工学部, English
ISSN：1880-4446, CiNii Articles ID：120001370434 - 勝鬨橋の再跳開技術に関する調査研究報告書
藤野陽三; 奥井義昭
2006 - 合成桁による設計思想の転換
奥井義昭
橋梁と基礎, Volume：40, Number：8, First page：64, Last page：67, 2006
建設図書, Japanese
ISSN：0287-170X, CiNii Articles ID：40007444667, CiNii Books ID：AN00062923 - 高減衰ゴムのマイクロメカニクスに基づく構成則モデルと破壊予測手法の開発
奥井 義昭
総合研究機構研究プロジェクト研究成果報告書, Number：4(17年度), 2006 - 鋼連続合成桁橋の構造合理化に関する技術検討業務報告書
長井正嗣; 奥井義昭
2006 - 鋼合成構造標準示方書の説明
奥井義昭
第11回鋼構造基礎講座「合成構造の設計と事例紹介」テキスト, 2006 - 硬岩の長期劣化予測を目的とした微視情報も算出可能な連続体理論の構築とその検証
奥井義昭; 小田匡寛
科学研究補助金研究成果報告書, 2006 - Ultimate Strength of Composite I-Girder in Pure Positive Bending
Nagai, M; Okui, Y; Inaba, N
7th Int. Conf. on Short & Medium Span Bridges, First page：ID-030-1-10, Last page：030-1-10, 2006 - FE Analysis with Smeared Crack Model for Crack Width Evaluation in Continuous Composite Girders
Okui, Y; Honda, Y; Khan, Q.Z; Nagai M
7th Int. Conf. on Short & Medium Span Bridges, First page：ID-034-1-7, Last page：034-1-7, 2006 - Effect of Initial Bending Moment in Composite Girder under Flexure for Unshored Construction
Gupta, V.K; Okui, Y; Nagai, M
7th Int. Conf. on Short & Medium Span Bridges, First page：ID-047-1-8, Last page：047-1-8, 2006 - 平成16年度鋼連続合成桁橋の構造合理化に関する技術検討報告書
長井正嗣,奥井義昭
（財）高速道路技術センター, 2005 - Rational design method for shear connector of composite girder bridges
奥井 義昭; 福永 靖雄
Volume：6, Number：6, First page：48, Last page：51, 2005
An analytical study on steel-concrete continuous composite girder bridges with precast concrete slab is carried out to investigate feasibility of composite bridges with precast concrete slabs. In composite girder bridges with precast concrete slab, the number of shear connectors is restricted owing to structural details of the precast panels. Accordingly, the effete of slip between the concrete slab and steel I girders on bridge behavior under service and ultimate loads is investigated to judge feasibility of composite girder bridges with precast concrete slab.
Japanese
ISSN：1347-4758, CiNii Articles ID：120001371355, CiNii Books ID：AA11808968 - 銀座線トンネル維持管理検討委員会報告書
魚本健人,奥井義昭
First page：1, Last page：380, 2005
東京地下鉄（株） - Ultimate strength of composite I-girder under pure sagging bending moment
Nagai M; Okui Y; Gupta V.K; Inaba N
First page：337, Last page：348, 2005 - Ultimate behavior and strength of composite girder under flexure - Proposition of innovative design method
Nagai M; Gupta V.K; Okui Y; Yasukawa Y; Inaba N
First page：4.3.91-98, 2005 - Simulation of Damage around a Circular Opening in Rock
Golshani A; Okui Y; Oda M
First page：33, Last page：40, 2005 - Simplified expressions for determining neutral axis depth in composite girders under positive bending
Gupta V.K; Okui Y; Nagai M
First page：53, Last page：56, 2005 - 平成16年度鋼連続合成桁橋の構造合理化に関する技術検討報告書
長井正嗣; 奥井義昭
（財）高速道路技術センター, 2005 - 合成桁のずれ止めの設計法に関する研究
奥井 義昭; 福永 靖雄
埼玉大学地域共同研究センター紀要, Volume：6, Number：6, First page：48, Last page：51, 2005
An analytical study on steel-concrete continuous composite girder bridges with precast concrete slab is carried out to investigate feasibility of composite bridges with precast concrete slabs. In composite girder bridges with precast concrete slab, the number of shear connectors is restricted owing to structural details of the precast panels. Accordingly, the effete of slip between the concrete slab and steel I girders on bridge behavior under service and ultimate loads is investigated to judge feasibility of composite girder bridges with precast concrete slab.
埼玉大学総合研究機構地域共同研究センター産学連携推進部門, Japanese
ISSN：1347-4758, CiNii Articles ID：120001371355, CiNii Books ID：AA11808968 - 銀座線トンネル維持管理検討委員会報告書
魚本健人; 奥井義昭
First page：1, Last page：380, 2005 - Ultimate strength of composite I-girder under pure sagging bending moment
Nagai M; Okui Y; Gupta V.K; Inaba N
The First International Road and Traffic Conference (ITRC), Proceedings -Roads to Global Society, Seoul, South Korea, First page：337, Last page：348, 2005 - Ultimate behavior and strength of composite girder under flexure - Proposition of innovative design method
Nagai M; Gupta V.K; Okui Y; Yasukawa Y; Inaba N
4th European conference on steel and composite structures, Eurosteel 2005, Maastricht, Netherlands, First page：4.3.91-98, Last page：98, 2005 - Simulation of Damage around a Circular Opening in Rock
Golshani A; Okui Y; Oda M
The 11th International Conference of IACMAG, Turin, Italy, First page：33, Last page：40, 2005 - Simplified expressions for determining neutral axis depth in composite girders under positive bending
Gupta V.K; Okui Y; Nagai M
Proceedings of the Seventh International Summer Symposium, JSCE, Tokyo, First page：53, Last page：56, 2005 - A METHOD FOR CRACK WIDTH EVALUATION OF CONTINUOUS COMPOSITE GIRDER BRIDGES ACCOUNTING FOR SHEAR-LAG EFFECT
KHAN Qaiser-uz-Zaman; HONDA Takuji; OKUI Yoshiaki; NAGAI Masatsugu
Number：738, First page：37, Last page：47, 21 Jul. 2003
English
ISSN：0289-7806, CiNii Articles ID：80016053243, CiNii Books ID：AN10014020 - 高減衰ゴムの微視構造の観察とマイクロメカニクスに基づく構成則の構築
奥井 義昭
科学研究費補助金基盤研究(C)(2)研究成果報告書, Volume：平成12-13年度, 2002 - 鋼コンクリート複合構造の力学特性解析法確立に関する研究
町田 篤彦,睦好 宏史,山口 宏樹,奥井 義昭,牧 剛史
科学研究費補助金(基盤研究(B)(2))研究成果報告書, Volume：平成11-13年度, 2002 - 高減衰ゴムの微視構造の観察とマイクロメカニクスに基づく構成則の構築
奥井 義昭
科学研究費補助金基盤研究(C)(2)研究成果報告書, Volume：平成12-13年度, 2002 - 鋼コンクリート複合構造の力学特性解析法確立に関する研究
町田 篤彦; 睦好 宏史; 山口 宏樹; 奥井 義昭; 牧 剛史
科学研究費補助金(基盤研究(B)(2))研究成果報告書, Volume：平成11-13年度, 2002 - Mechanical characteristics and constitutive models of high damping rubber for bridge bearings
OKUI Yoshiaki; Amin A.F.M. Saiful
Volume：2002, Number：2, First page：75, Last page：80, 2002
Fundamental mechanical characteristics of high damping rubber (HDR) for bridge bearings are introduced and reviewed through comparison with those of natural rubber (NR). Attention is given to behavior of HDR under compression. Rubber constitute models are addressed. Several hyperelastic models are compared for simulating HDR behavior with a constant strain rate. An improved hyperelasticity model is proposed to reproduce the rate-independent behavior of HDR including high initial stiffness at low stretch levels. The proposed hyperelastic model is incorporated into a rate-dependent finite-strain model structure.
Japanese
CiNii Articles ID：110002484301, CiNii Books ID：AA11901817 - 合成斜張橋の動向と技術的課題
長井 正嗣; 奥井 義昭; 岩崎 英治
Volume：35, Number：11, First page：27, Last page：34, Nov. 2001
Japanese
ISSN：0287-170X, CiNii Articles ID：40000754294, CiNii Books ID：AN00062923
- 鋼構造架設設計施工指針
鋼構造委員会; 鋼構造架設設計施工指針改定小委員会, [Joint work]
Jan. 2025
ISBN：9784810611212 - 土木構造設計2 [工業 752]
奥井 義昭, [Supervisor]
Jan. 2023
Japanese, Total pages：290
CiNii Books：http://ci.nii.ac.jp/ncid/BD01903827
ISBN：4407205636, ASIN：4407205636, EAN：9784407205633, CiNii Books ID：BD01903827 - 土木製図 [工業 706]
奥井義昭, [Supervisor]
Jan. 2022
Japanese, Total pages：251
CiNii Books：http://ci.nii.ac.jp/ncid/BC14375553
ISBN：4407204419, ASIN：4407204419, EAN：9784407204414, CiNii Books ID：BC14375553 - 鋼構造学
伊藤, 学; 奥井, 義昭, [Joint work]
Mar. 2020
Japanese, Total pages：viii, 245p
CiNii Books：http://ci.nii.ac.jp/ncid/BB29782611
ISBN：9784339052695, CiNii Books ID：BB29782611 - 窪田陽一監修，久保田尚, 奥井義昭他 道路が一番わかる：道路の構造・工法が手に取るように理解できる しくみ図解シリーズ
Oct. 2009
ISBN：4774140058 - 鋼橋性能向上研究委員会・合理化設計法部会, 奥井義昭 合成桁の限界状態設計法試案 JSSCテクニカルレポート
2006 - 鋼橋性能向上研究委員会・合理化設計法部会, 奥井義昭 合成桁の限界状態設計法試案 JSSCテクニカルレポート
社）日本鋼構造協会, 2006 - Continuum models for materials with microstructure
Okui, Y.; Horii, H.; Ed.Mühlhaus; H, [Contributor], Chapter 2 A Micromechanics-based Continuum Theory for Microcracking Localization of Rocks under Compression
Wiley, Mar. 1996
English, Total pages：492
CiNii Books：http://ci.nii.ac.jp/ncid/BA26435851
ISBN：0471950653, ASIN：0471950653, EAN：9789810244125, CiNii Books ID：BA26435851
- 鋼トラス橋を対象としたリダンダンシー評価ガイドラインの開発
2009 - プレキャスト床版連続合成桁のスタッドに関する実験
2009 - 低塔を有する200m合成斜張橋の弾塑性挙動と終局強度
2009 - 合成桁中間支点部の曲げ強度評価に関する一考察
2009 - Seismic response analysis of base isolated highway bridge:effect of isolation bearing's modeling
2009 - A Simplified Rheology Model of Natural and Lead Rubber Bearings for Seismic Analysis
2009 - 鋼トラス橋を対象としたリダンダンシー評価ガイドラインの開発
2008年度公募研究成果梗概集, 2009 - プレキャスト床版連続合成桁のスタッドに関する実験
土木学会第64回年次学術講演会, 2009 - 低塔を有する200m合成斜張橋の弾塑性挙動と終局強度
土木学会第64回年次学術講演会, 2009 - 合成桁中間支点部の曲げ強度評価に関する一考察
土木学会第64回年次学術講演会, 2009 - Seismic response analysis of base isolated highway bridge:effect of isolation bearing's modeling
土木学会第64回年次学術講演会, 2009 - A Simplified Rheology Model of Natural and Lead Rubber Bearings for Seismic Analysis
土木学会第64回年次学術講演会, 2009 - 耐震設計用レオロジーモデルとパラメータの同定：RBとLRBの場合
2008 - Experimental investigation of laminated rubber bearings and their modeling: High damping rubber bearing
2008 - 塑性中立軸が床版内にある合成I桁の正曲げ強度に関する実験的研究
2008 - 鋼トラス橋のリダンダンシー評価手法の検討（その３）
2008 - 鋼トラス橋のリダンダンシー評価手法の検討（その２）
2008 - 鋼トラス橋のリダンダンシー評価手法の検討（その１）
2008 - せん断を受けるI桁のエンドパネルの影響に関する実験検討
2008 - NONLINEAR VISCOSITY OF HIGH DAMPING RUBBER BEARINGS: EXPERIMENTAL INVESTIGATION AND RHEOLOGY MODEL
2008 - Strength of headed stud shear connectors in steel-concrete composite beams with precast decks
2008 - Experimental investigation of laminated rubber bearings at low temperatures
2008 - 曲げとせん断を受けるハイブリッドI桁の耐力に関する実験検討
2008 - 耐震設計用レオロジーモデルとパラメータの同定：RBとLRBの場合
第63回土木学会北海道支部, 2008 - Experimental investigation of laminated rubber bearings and their modeling: High damping rubber bearing
64th JSCE Annual Conference Hokkaido, 2008 - 塑性中立軸が床版内にある合成I桁の正曲げ強度に関する実験的研究
土木学会第63回年次学術講演会, 2008 - 鋼トラス橋のリダンダンシー評価手法の検討（その３）
土木学会第63回年次学術講演会, 2008 - 鋼トラス橋のリダンダンシー評価手法の検討（その２）
土木学会第63回年次学術講演会, 2008 - 鋼トラス橋のリダンダンシー評価手法の検討（その１）
土木学会第63回年次学術講演会, 2008 - せん断を受けるI桁のエンドパネルの影響に関する実験検討
土木学会第63回年次学術講演会, 2008 - NONLINEAR VISCOSITY OF HIGH DAMPING RUBBER BEARINGS: EXPERIMENTAL INVESTIGATION AND RHEOLOGY MODEL
土木学会第63回年次学術講演会, 2008 - Strength of headed stud shear connectors in steel-concrete composite beams with precast decks
Proceedings of the Tenth International Summer Symposium, JSCE, 2008 - Experimental investigation of laminated rubber bearings at low temperatures
Proceedings of the Tenth International Summer Symposium, JSCE, 2008 - 曲げとせん断を受けるハイブリッドI桁の耐力に関する実験検討
土木学会第63回年次学術講演会, 2008 - 合成I桁の曲げ耐荷力の実験検討
2007 - 合成I桁の曲げ強度評価に関する一考察
2007 - A rheology model of rubber bearing for seismic analysis of bridges
2007 - 積層ゴム支承の地震応答解析用レオロジーモデル
2007 - 水平スタッドのせん断特性に関する実験的研究（その２） せん断強度の評価
2007 - 水平スタッドのせん断特性に関する実験的研究（その1） 水平スタッドの終局挙動
2007 - A rheology model of rubber bearing for seismic analysis of bridges
2007 - ２重合成Ｉ桁中間支点部の曲げ耐力に関する実験検討
2007 - Design of Composite Bridges-Lateral Distortional Buckling-
2007 - Web Slenderness Limits for Section Classification of Composite Girders
2007 - Development of Steel/Concrete Hybrid Bridges in Japan
2007 - Load carrying capacity of cable-stayed composite girder bridges with segmental cantilever erection
2007 - ゴム支承を対象とした耐震設計用レオロジーモデル
2007 - Development of hybrid bridges and design innovation in Japan
2007 - Design issues for steel-concrete composite girders,
2007 - Composite bridges in Japan
2007 - 合成I桁の曲げ耐荷力の実験検討
土木学会第61回年次学術講演会概要集, 2007 - 合成I桁の曲げ強度評価に関する一考察
土木学会第61回年次学術講演会概要集, 2007 - A rheology model of rubber bearing for seismic analysis of bridges
9th JSCE International Summer Symposium, Yokohama, Japan, 2007 - 積層ゴム支承の地震応答解析用レオロジーモデル
土木学会第62回年次学術講演会概要集, 2007 - 水平スタッドのせん断特性に関する実験的研究（その２） せん断強度の評価
土木学会第62回年次学術講演会概要集, 2007 - 水平スタッドのせん断特性に関する実験的研究（その1） 水平スタッドの終局挙動
土木学会第62回年次学術講演会概要集, 2007 - A rheology model of rubber bearing for seismic analysis of bridges
土木学会第62回年次学術講演会概要集, 2007 - ２重合成Ｉ桁中間支点部の曲げ耐力に関する実験検討
土木学会第62回年次学術講演会概要集, 2007 - Design of Composite Bridges-Lateral Distortional Buckling-
Japan-Korea joint workshop on steel bridge design specification, Hokkaido univ., Japan, 2007 - Web Slenderness Limits for Section Classification of Composite Girders
Proc. of JSCE-EIT Joint Seminar on Recent code development and advanced technologies of steel and composite bridges, 2007 - Development of Steel/Concrete Hybrid Bridges in Japan
Proc. of JSCE-EIT Joint Seminar on Recent code development and advanced technologies of steel and composite bridges, 2007 - Load carrying capacity of cable-stayed composite girder bridges with segmental cantilever erection
Proc. of SIIT-Saitama University joint seminar, 2007 - ゴム支承を対象とした耐震設計用レオロジーモデル
土木学会北海道支部年次技術研究発表会概要集, 2007 - Development of hybrid bridges and design innovation in Japan
Proc. of China-Japan joint seminar on steel and composite bridges, 2007 - Design issues for steel-concrete composite girders,
Proc. of China-Japan joint seminar on steel and composite bridges, 2007 - Composite bridges in Japan
Proc. of Japan-China Conference on Structural Steel Construction, 2007 - 合成桁の断面分類と強度式の検討
2006 - 合成I桁の曲げ強度評価におけるductility条件
2006 - Lateral distortional buckling of steel and concrete composite twin I-girder
2006 - Topics on Strength, Section Classification, Ductility requirements of Composite Girders in Japan
2006 - Crack Width Evaluation Method accounting for shear-lag effect and effective width
2006 - On design of composite girder bridges
2006 - 高減衰ゴムの非線形粘性則の同定と有限ひずみ構成則でのシミュレーション,
2006 - Web Slenderness Ratio Considering Initial Bending Moment Effect on Composite Girders during Construction Phase
2006 - Topics on ultimate strength of composite girders in Japan
2006 - 合成桁の断面分類と強度式の検討
土木学会関東支部新潟会研究調査発表会概要集, 2006 - 合成I桁の曲げ強度評価におけるductility条件
土木学会関東支部新潟会研究調査発表会概要集, 2006 - Lateral distortional buckling of steel and concrete composite twin I-girder
土木学会関東支部新潟会研究調査発表会概要集, 2006 - Topics on Strength, Section Classification, Ductility requirements of Composite Girders in Japan
Proc. of Korea-Japan Joint Seminar on Steel-Concrete Composite Bridges, 2006 - Crack Width Evaluation Method accounting for shear-lag effect and effective width
Proc. of Korea-Japan Joint Seminar on Steel-Concrete Composite Bridges, 2006 - On design of composite girder bridges
Proc. of Vietnum-Japan joint seminar on steel bridges, 2006 - 高減衰ゴムの非線形粘性則の同定と有限ひずみ構成則でのシミュレーション,
土木学会第61回年次学術講演会概要集, 2006 - Web Slenderness Ratio Considering Initial Bending Moment Effect on Composite Girders during Construction Phase
土木学会第61回年次学術講演会概要集, 2006 - Topics on ultimate strength of composite girders in Japan
Korea-Japan Joint Workshop on Steel Bridge Design Specifications, 2006 - 合成桁の終局曲げ強度特性の解明に関する研究
2005 - 逆解析手法による高減衰ゴムの非線形粘性則の同定
2005 - 連続合成桁の初期ひび割れ性状の解明に関する実験的研究,
2005 - 合成桁におけるずれ止めの限界状態設計のための解析的研究
2005 - ずれ止めの変形を考慮した連続合成桁の3次元FEM解析
2005 - The effect of initial moment on the ultimate load-carrying capacity of composite girder under flexure
2005 - On Analytical Study for Steel-Concrete Compopsite Girders, Seminar on Recent Advances in Steel Bridges in Japan
2005 - 合成桁の終局曲げ強度特性の解明に関する研究
土木学会第60回年次学術講演会講演概要集,, 2005 - 逆解析手法による高減衰ゴムの非線形粘性則の同定
土木学会第59回年次学術講演会講演概要集, 2005 - 連続合成桁の初期ひび割れ性状の解明に関する実験的研究,
土木学会第60回年次学術講演会講演概要集, 2005 - 合成桁におけるずれ止めの限界状態設計のための解析的研究
土木学会第60回年次学術講演会講演概要集, 2005 - ずれ止めの変形を考慮した連続合成桁の3次元FEM解析
土木学会第60回年次学術講演会講演概要集, 2005 - The effect of initial moment on the ultimate load-carrying capacity of composite girder under flexure
60th Annual Proceeding of Japanese Society of Civil Engineers, JSCE, Japan, 2005 - On Analytical Study for Steel-Concrete Compopsite Girders, Seminar on Recent Advances in Steel Bridges in Japan
Proc. of Bridge Engneering, 2005 - Some topics of studies for steel-concrete composite girders
Okui Y; Gupta V.K
Proc. of 8th Korea-China-Japan Symposium on steel structure, Seoul, 2005 - Load-carrying capacity of composite girders in cable-stayed bridges
Okui Y; Nagai M; Iwasaki E; Hirono T
4th European conference on steel and composite structures, Eurosteel 2005, Maastricht, Netherlands, 2005 - Proceedings of the Japan-Bangladesh Joint SEminar on Advances in Bridges Eng.
Amin; A.F.M.S; Okui, Y; Safiullah; A.M.M editor
The instituton of Engineers, Bangladsh, 2005 - Hydraulic behaviour of Inada granite in the excavation disturbed zone around underground openings
Golshani, A; Okui, Y; Oda, M; Takemura, T
Proceedings of the Seventh International Summer Symposium, JSCE, Tokyo, 2005 - Analytical study on steel-concrete composite girders
Okui Y
Proc. of Japan-Bangladesh Joint Seminar on Advances in Bridge Engineering, Dhaka, Bangladesh, 2005 - 連続合成２主桁橋のひび割れ幅算定を目的とした有効幅の検討
2004 - 連続合成２主桁橋のひび割れ幅算定を目的とした有効幅の検討
土木学会第59回年次学術講演会講演概要集, 2004 - Time dependent continuous damage model for brittle failure of rocks
Golshani, A; Okui, Y; Takemura, T; Oda
EUROCK 2004 & 53rd Geomechanics Colloquium, Schubert (ed.), 2004
■ Affiliated academic society
■ Research projects
- Development of an existing bridge management method based on load rating
Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (B), 01 Apr. 2021 - 31 Mar. 2024
Saitama University
Grant amount(Total)：15340000, Direct funding：11800000, Indirect funding：3540000
Grant number：21H01415 - Development of design procedure for high damping rubber bearings under low temperatures and modeling of Mullins' effect
Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (B), 01 Apr. 2014 - 31 Mar. 2017
OKUI Yoshiaki; IMAI Takashi, Saitama University
Grant amount(Total)：15470000, Direct funding：11900000, Indirect funding：3570000
The temperature dependence of mechanical characteristics of high damping rubber bearings (HDRBs) was investigated through cyclic loading tests under different ambient temperatures, especially sub-zero environment. The ambient temperatures and temperatures inside HDRBs during cyclic loading were
different due to self hating, and it is found that mechanical behavior of HDRBs is governed by the inside temperatures. A simple method to estimate the inside temperature was developed on the basis of the cyclic loading tests and thermal conductivity analyses results. Previous cyclic loading tests results at different ambient temperatures were reexamined based on the inside temperatures to estimate temperature dependence of HDRBs.
Grant number：26289140 - Mechanism of damage-induced local damping and structural health monitoring of bridges based on damping change
Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (A), 01 Apr. 2011 - 31 Mar. 2015
YAMAGUCHI Hiroki; MATSUMOTO Yasunao; OKUI Yoshiaki; ASAMOTO Shingo; MUTSUYOSHI Hiroshi, Saitama University
Grant amount(Total)：42250000, Direct funding：32500000, Indirect funding：9750000
Damages (such as tension crack, corrosion and partial fracture) and damage –induced local damping increment in steel member, concrete member and steel-concrete interface are first experimentally studied to discuss the mechanism of local damping increased by local damages. The evaluation method of structural health condition for steel, RC and PC bridges is then proposed by developing a hybrid method of experimental and analytical modal syntheses based on ambient vibration measurement and global damping change monitoring. The method of ambient vibration measurement is carefully studied for optimizing it as a system and the identification of global damping change in bridges is refined with FE model updating method. How to implement the proposed method of bridge health evaluation to the Bridge Management System was finally discussed.
Grant number：23246082 - Development of a rheology model of laminated rubber bearings for seismic design: Establishment of design method at low temperature
Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (C), 2010 - 2012
OKUI Yoshiaki, Saitama University
Grant amount(Total)：4290000, Direct funding：3300000, Indirect funding：990000
A seismic design model of base-isolation rubber bearings for nonlinear dynamic analyses is investigated especially under low temperature conditions. The rubber bearing tests are carried out in low temperatures environment up to -30 C deg. to identify temperature dependency of mechanical behavior. A rheology model including elastic-visco-plastic elements is developed to reproduce strain-rate dependent response prominent in high damping rubber bearings and elastic-plastic response in lead rubber bearings.
Grant number：22560473 - Structural redundancy/collapse analysis, dynamic analysis and structural health monitoring of steel truss bridges
Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (B), 2008 - 2010
YAMAGUCHI Hiroki; OKUI Yoshiaki; MATSUMOTO Yasunao; YOSHIOKA Tsutomu; ITO Shin, Saitama University
Grant amount(Total)：18590000, Direct funding：14300000, Indirect funding：4290000
The fracture critical members were identified by conducting the structural redundancy analysis of steel truss bridges and the effects of load-carrying capacity of concrete deck as well as member joint were investigated. The dynamic characteristics of truss bridges, classified into the global, local and coupled modes, were also clarified in detail by the experimental/theoretical modal analyses. The feasibility of vibration-based health monitoring of steel truss bridges, based on the field measurement as well as the impulse hummer test, was finally discussed by showing the fact that the damping ratios of coupled modes and the group of higher natural frequencies in local modes can be changed in identifiable amount by having local damages in truss diagonal members.
Grant number：20360198 - Development of the most competitive performance-based limit state design method for composite girders
Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (B), 2006 - 2007
NAGAI Masatsugu; OKUI Yoshiaki; IWASAKI Eiji, Nagaoka University of Technology
Grant amount(Total)：16740000, Direct funding：15300000, Indirect funding：1440000
Performance-based Limit State Design Method (PB-LSD) for designing structural members for infrastructure is now global standard. In Euro Code (EU) and AASHTO LRFD (USA), after 20-year energetic activity, the shift of design concept from Allowable Stress Design (ASD) to PB-LSD has just finished. Among Asian countries, where future preparation of infrastructure is expected and also are expected to be promising market, the above codes are now becoming popular. In Japan, for more than 30 years, ASD has been used. On designing composite girders, which is competitive structural members, and has been employed worldwide, in order to effectively utilize its mechanical characteristics, introduction of LSD is inevitable. From a viewpoint of competing with EC (EU) and AASHTO LRFD (USA), a shift from ASD to LSD has to be done immediately. In this research, based on analytical and experimental studies, original and competitive formulae for evaluating ultimate flexure, shear and interactive strength for composite girders were proposed, which are the most important items on establishing competitive LSD. On evaluating flexural strength, the criterion for judging to be compact section gives the most economical section. Regarding ductility condition taking into account of the decrease of plastic moment due to concrete crushing, the most competitive solution was given. On evaluating flexure and shear interactive strength, it was found that the interaction effect can be neglected in case of composite girders. In case of steel girder (under erection), it has to be checked. Original provisions were also proposed on checking serviceability limit state. Furthermore, the design method for double-composite girders and composite hybrid girders was also proposed.
Grant number：18360214 - Establishment of Analytical Methodology for Mechanical,Characteristics of Steel-Concrete Hybrid Structures
Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (B), 1999 - 2001
MACHIDA Atsuhiko; OKUI Yoshiaki; YAMAGUCHI Hiroki; MUTSUYOSHI Hiroshi; TAKESI Maki, Saitama University
Grant amount(Total)：8300000, Direct funding：8300000
(1) A FEM program was developed to analyze the mechanical behavior of hybrid structures in which steel girders are rigidly connected to RC pier. In this program, concrete was assumed as homogeneous material, and Mohr-Coulomb's failure criterion was adopted considering strain softening. In order to treat bonding phenomena between concrete and reinforcing bar or steel plate rigorously, bonding elements were developed based on the previously proposed models and incorporated into the program. In particular, the bonding element between concrete and steel plate can express slip and exfoliation phenomena. The developed program can be applied to composite structures in general.
(2) Comparison of analysis with experimental results showed that the developed program can trace the behavior accurately up to large deformation region.
(3) Analysis on the hybrid structures of actual scale showed that, unless some special measures are taken, most of the load from super structure is transferred to the connection and its vicinity, hardly distributing to the lateral direction.
(4) A strut and tie model, which can analyze the behavior more simply and can be used as design tool, was developed based on the analysis.
Grant number：11450169 - 結晶性硬岩の超長期劣化問題に対する解析モデルの開発
Competitive research funding - 橋梁維持管理のためのリダンダンシーやVulnerability assessmentに関する研究
Competitive research funding - 橋梁用ゴム支承の耐震設計用レオロジーモデルの開発とゴム支承の温度依存性に関する研究
Competitive research funding - 橋梁設計における安全係数の合理的決定法に関する研究
Competitive research funding - 鋼橋および合成桁の設計法に関する研究
Competitive research funding - Development of super long-term deterioration prediction models for crystalline rocks
Competitive research funding - Redundancy and vulnerability assessment of steel structures for bridge maintenance
Competitive research funding - Mechanical model of laminated rubber bearings for seismic design
Competitive research funding - Research on safety factors for structural design
Competitive research funding - Design method for steel and composite structures
Competitive research funding