Kei Kimura, Takeshi Onogi and Fuminobu Ozaki
This work examines the effects of strain rate on the effective yield strength of high-strength steel at elevated temperatures, through tensile coupon tests at various strain…
Abstract
Purpose
This work examines the effects of strain rate on the effective yield strength of high-strength steel at elevated temperatures, through tensile coupon tests at various strain rates, to propose appropriate reduction factors considering the strain rate effect.
Design/methodology/approach
The stress–strain relationships of 385 N/mm2, 440 N/mm2 and 630 N/mm2-class steel plates at elevated temperatures are examined at three strain rate values (0.3%/min, 3.0%/min and 7.5%/min), and the reduction factors for the effective yield strength at elevated temperatures are evaluated from the results. A differential evolution-based optimization is used to produce the reduction-factor curves.
Findings
The strain rate effect enhances with an increase in the standard design value of the yield point. The effective yield strength and standard design value of the yield point exhibit high linearity between 600 and 700 °C. In addition to effectively evaluating the test results, the proposed reduction-factor curves can also help determine the ultimate strength of a steel member at collapse.
Originality/value
The novelty of this study is the quantitative evaluation of the relationship between the standard design value of yield point at ambient temperature and the strain-rate effect at elevated temperatures. It has been observed that the effect of the strain rate at elevated temperatures increases with the increase in the standard design value of the yield point for various steel strength grades.
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Kei Kimura, Takeshi Onogi, Naoya Yotsumoto and Fuminobu Ozaki
In this study, the effects of strain rate on the bending strength of full-scale wide-flange steel beams have been examined at elevated temperatures. Both full-scale loaded heating…
Abstract
Purpose
In this study, the effects of strain rate on the bending strength of full-scale wide-flange steel beams have been examined at elevated temperatures. Both full-scale loaded heating tests under steady-state conditions and in-plane numerical analysis using a beam element have been employed.
Design/methodology/approach
The load–deformation relationships in 385 N/mm2-class steel beam specimens was examined using steady-state tests at two loading rate values (0.05 and 1.00 kN/s) and at two constant member temperatures (600 and 700 °C). Furthermore, the stress–strain relationships considering the strain rate effects were proposed based on tensile coupon test results under various strain rate values. The in-plane elastoplastic numerical analysis was conducted considering the strain rate effect.
Findings
The experimental test results of the full-scale steel beam specimens confirmed that the bending strength increased with increase in strain rate. In addition, the analytical results agreed relatively well with the test results, and both strain and strain rate behaviours of a heated steel member, which were difficult to evaluate from the test results, could be quantified numerically.
Originality/value
The novelty of this study is the quantification of the strain rate effect on the bending strength of steel beams at elevated temperatures. The results clarify that the load–deformation relationship of steel beams could be evaluated by using in-plane analysis using the tensile coupon test results. The numerical simulation method can increase the accuracy of evaluation of the actual behaviour of steel members in case of fire.
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Xiaomin Zhao, Fuminobu Ozaki, Takeo Hirashima, Kei Kimura, Yukio Murakami, Jun-ichi Suzuki and Naoya Yotsumoto
The main purpose of this study was to propose theoretical calculation models to evaluate the theoretical bending strengths of welded wide-flange section steel beams with local…
Abstract
Purpose
The main purpose of this study was to propose theoretical calculation models to evaluate the theoretical bending strengths of welded wide-flange section steel beams with local buckling at elevated temperatures.
Design/methodology/approach
Steady-state tests using various test parameters, including width-thickness ratios (Class 2–4) and specimen temperatures (ambient temperature, 400, 500, 600, 700, and 800°C), were performed on 18 steel beam specimens using roller supports to examine the maximum bending moment and bending strength after local buckling. A detailed calculation model (DCM) based on the equilibrium of the axial force in the cross-section and a simple calculation model (SCM) for a practical fire-resistant design were proposed. The validity of the calculation models was verified using the bending test results.
Findings
The strain concentration at the local buckling cross-section was mitigated in the elevated-temperature region, resulting in a small bending moment degradation after local buckling. The theoretical bending strengths after local buckling, evaluated from the calculation models, were in good agreement with the test results at elevated temperatures.
Originality/value
The effect of local buckling on the bending behaviour after the maximum bending strength in high-temperature regions was quantified. Two types of calculation models were proposed to evaluate the theoretical bending strength after local buckling.
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Yutaka Horiba and Kazuo Yoshida
This paper investigates the empirical determinants of the initial FDI entry decisions by Japanese firms to enter into the U.S and Taiwanese markets. The study is based on a…
Abstract
This paper investigates the empirical determinants of the initial FDI entry decisions by Japanese firms to enter into the U.S and Taiwanese markets. The study is based on a full-sample survey of firms listed on Japanese stock exchanges and is for the period 1976–2000. We find that a number of macro/financial as well as micro (company-specific) variables are highly significant in explaining the observed entry pattern.
This study aims to provide the history and overview of the major categories of physical education (PE) assistance that Japan has provided to other countries by extracting the…
Abstract
Purpose
This study aims to provide the history and overview of the major categories of physical education (PE) assistance that Japan has provided to other countries by extracting the major categories from the various materials.
Design/methodology/approach
This study is divided into two phases, Phases 1 and 2. Surveys and analyses were further conducted. In Phase 1, a web browser-based survey was conducted to ascertain the major categories of PE assistance that Japan has provided to other countries. The practices and projects investigated were classified inductively, and the major categories were extracted. In Phase 2, a literature review was conducted to organise the history and overview of each category extracted in Phase 1.
Findings
Six major categories were extracted: (1) dispatch of Japan Overseas Cooperation Volunteers engaged in PE assistance, (2) assistance through training for those involved in PE, (3) revision or formulation of a PE curriculum, (4) preparation of textbooks or instructional materials for PE, (5) organising sports event and (6) maintenance of PE equipment and facilities.
Originality/value
Japan has a long history of providing PE assistance to other countries. However, historical materials on the practices and projects of PE are becoming scattered. Little literature addresses this gap, which this study seeks to address. This study can help policy makers in other countries, who can use Japan’s PE assistance practices and policies for reference, to assist them in formulating their own policies.
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Shigeru Asaba and Hideki Yamawaki
This study examines the determinants of performance of foreign manufacturing subsidiaries in Japan. The study finds that a foreign parent’s size, the subsidiary’s age, and a…
Abstract
This study examines the determinants of performance of foreign manufacturing subsidiaries in Japan. The study finds that a foreign parent’s size, the subsidiary’s age, and a complicated distribution system influence a subsidiary’s performance. There was little significant change in these determinants over a 20-year period. However, for subsidiaries that survived over the observation period of this study, some determinants changed. We also found that by forming joint ventures with Japanese firms, foreign firms can overcome the obstacle of distribution and circumvent the disadvantage of inexperience. Moreover, the mitigating effects of joint ventures vary, depending on the type of Japanese partner.