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Tokyo, Japan

Obayashi Corporation is one of five major Japanese construction companies along with Shimizu Corporation, Takenaka Corporation, Kajima Corporation, and Taisei Corporation. It is listed on the Tokyo Stock Exchange and is one of the Nikkei 225 corporations. Its headquarters are in Minato, Tokyo.Established in 1892 in Osaka, Obayashi operates in Japan and other countries, especially Southeast Asia and Australia, as well as the United States and Europe. Major landmarks in Japan include the Kyoto Station Building and Tokyo Broadcasting System Center in Tokyo, as well as the Tokyo Skytree.Obayashi has 86 subsidiaries and 26 affiliated companies in Japan, Europe, the Middle East, Asia, Australia and North America.In February 2012 it announced plans to build a space elevator by 2050. Wikipedia.

Takabatake H.,Kanazawa Institute of Technology | Yasui M.,Obayashi Corporation | Nakagawa Y.,UNION SYSTEM INC. | Kishida A.,Kanazawa Institute of Technology
Earthquake Engineering and Structural Dynamics | Year: 2014

SUMMARY: Earthquake-induced structural pounding frequently causes serious damage to buildings, particularly at the expansion joint (hereafter, EXPJ) between adjacent buildings. Because the EXPJ width in existing reinforced concrete buildings is usually very small, typically about 5cm for school buildings in Japan, collision avoidance cannot be achieved by seismic retrofitting. This paper presents an experimental investigation into an effective method for reducing severe structural damage due to pounding at the EXPJ between narrowly separated buildings. The method involves inserting a shock-absorbing material such as rubber into the EXPJ gap. The efficiency of the proposed method is evaluated by laboratory shaking tests using two model buildings. Furthermore, a lumped mass model is used to carry out a collision analysis in order to numerically investigate the influence of such a shock-absorbing material. Both the numerical and experimental results confirm the effectiveness of the proposed approach. The validity of the proposed method is also demonstrated by numerical simulation of adjacent 10-story steel buildings with an EXPJ width of 5cm. The force, acceleration and velocity produced by earthquake-induced structural pounding are found to be remarkably mitigated by inserting a soft shock-absorbing material into the EXPJ gap. © 2014 John Wiley & Sons, Ltd. Source

Watanabe K.,Obayashi Corporation | Kusakabe O.,Ibaraki National College of Technology | Kusakabe O.,Tokyo Institute of Technology
Soils and Foundations | Year: 2013

This study re-visits the effects of loading rate on sand behavior in view of seismic design of pile foundation. Based on an extensive literature review covering both element testing and model testing, the paper summarizes the current understanding of the loading rate effects. The paper then describes the development of test apparatus used in this study and presents the data obtained from a series of monotonically increasing triaxial compression tests on Toyoura sand, varying the strain rate in the range of 0.005%/s to 250%/s. A total of 36 tests were conducted on dry and saturated sand, both under drained and undrained conditions with two confining pressures. The experimental results confirm that the soil strength and the soil stiffness increase as the strain rate increase. This paper also concludes that the internal friction angle and deformation modulus increase when the strain rate is high. The implications of the loading rate effect on pile foundation design are then presented. © 2013 The Japanese Geotechnical Society. Production and hosting by Elsevier B.V. All rights reserved. Source

Suwa Y.,Obayashi Corporation
Journal of Environmental Engineering | Year: 2011

In the Internet data centers (iDCs), a large amount of heat generated by server machines should be removed efficiently from the server rooms so that the room temperature can be controlled at a suitable level to keep these machines in good working condition. In this study, a computational fluid dynamics (CFD) simulation was carried out for various air-conditioning systems, and the ventilation and air-conditioning performance were compared. As the result, systems with both supply and return openings on the ceiling showed the best performance. This system exhibited much better performance than any other conventional systems. In addition, it was flexible with regard to the arrangement of server racks, and it performed well even in case of large heat generation. Source

Ito K.,Kyushu University | Harashima H.,Obayashi Corporation
Building and Environment | Year: 2011

Recently, theoretical analysis and experiment have been initiated to investigate the generation of secondary organic aerosols (SOA) by chemical reactions in indoor air. In particular, it has been confirmed that SOA are generated by the reaction of ozone with various terpenoids. The overarching goal of this work was to better understand ozone, VOC (volatile organic compounds) and generated SOA distributions within rooms. We carried out cylindrical test chamber experiments to measure SOA generation from the chemical reaction of ozone and limonene and discussed numerical models to describe it. In this paper, we propose a method for predicting the particle size distribution of SOA generated by ozone and limonene chemical reactions in air. In particular, we discuss an analytical method that involves a sectional modeling approach governing equations of SOA. Although the changes in particle size distribution in a 40-section model were reproduced to a certain extent, rigorous modeling for the generation and growth of SOA and an increased number of sections are needed for improvement of prediction accuracy. © 2010 Elsevier Ltd. Source

The present invention provides cement composition including 100 parts by weight of binder (B) including, 5-30 parts by weight of cement, 0-20 parts by weight of silica fume, 0-50 parts by weight of fly ash, and 42-75 parts by weight of blast furnace slag; water (W) equivalent to 80-185 kg/m

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