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Yasui H.,Izumi Sohken Engineering Co. | Ohkuma T.,Kanagawa University | Yoshie K.,Nikken Sekkei Ltd. | Tsurumi T.,Izumi Sohken Engineering Co.
AIJ Journal of Technology and Design | Year: 2013

Increasing number of high-rise buildings are being equipped with energy absorption devices of elasto-plastic materials. It is important to ensure the safety of these devices to not only under design wind speed but also under cumulative fatigue damage due to wind loading during use. In determining cumulative damage, it is necessary to evaluate the cumulative time of wind speed in a period and the wind response to each wind speed. This paper presents a simple method for evaluating the cumulative time of wind speed in a period and its effectiveness.

Yoshie R.,Tokyo Polytechnic University | Tominaga Y.,Niigata Institute of Technology | Ito S.,Konoike Construction Co. | Okada H.,Izumi Sohken Engineering Co. | And 9 more authors.
Journal of Wind Engineering | Year: 2014

A criterion for pedestrian wind environment based on probability of exceedance of daily maximum gust wind speed is commonly used in Japan. We usually use gust factors to estimate the daily maximum gust wind speeds, using daily maximum mean wind speeds. But there still remains an unsettled problem of how to determine the appropriate gust factors. "A Working Group for Urban Wind Environment Assessment" in the Japan Association for Wind Engineering has been studying this problem to establish rational wind environment assessment method. The WG proposes a model equation of the gust factors based on field observation data at 152 sites, and confirms the applicability of it to the assessment of pedestrian wind environment.

Katagiri J.,Izumi Sohken Engineering Co. | Ohkuma T.,Kanagawa University | Yasui H.,Izumi Sohken Engineering Co. | Marukawa H.,Izumi Sohken Engineering Co. | Tsurumi T.,Izumi Sohken Engineering Co.
AIJ Journal of Technology and Design | Year: 2011

This study investigates the accuracy of eigenvalues and wind responses obtained from a reduced model of a high-rise building with a base isolation system. The reduceb models are made targeting buildings above the bate isolation system. The along-wind displacements at the first floor of a building are estimated S accurately if the building is modeled by two or mocre masses system. For across-wind and torsional wind response there are large errors in calculating the displacement with using a reduced model presented with a few masses in comparison with those with five or more masses.

Hirai H.,Tokyo University of Science | Yoshie K.,Nikken Sekkei Ltd. | Sato D.,Tokyo University of Science | Katagiri J.,Izumi Sohken Engineering Co. | And 3 more authors.
AIJ Journal of Technology and Design | Year: 2012

In evaluation of wind-induced responses through time-history analysis based on stationary random process, its responsive value must be dealt with numerous numbers of statistics. However, the designing value is often determined from the small number of samples because of limited time and expense in practice. Therefore, it is important and necessary to grasp dispersion of wind response from small number of samples. In this paper, the dispersion of wind forces and wind-induced responses are investigated from wind tunnel tests. Then, the influence on wind responses due to the difference in the number of samples used as an ensemble average is elucidated.

Junji Katagiri,Izumi Sohken Engineering Co. | Takeshi Ohkuma,Kanagawa University | Hisao Marukawa,Izumi Sohken Engineering Co. | Hachinori Yasui,Izumi Sohken Engineering Co.
Journal of Structural and Construction Engineering | Year: 2012

This study investigates unsteady aerodynamic responses of base-isolated high-rise buildings. First, an approximation method for motion-induced wind forces for time-domain analysis of high-buildings is suggested. Second, wind response analyses for base-isolated high-rise buildings composed of rubber isolators and lead dampers are carried out using approximated motion-induced wind forces. The following results were obtained. 1) Approximated values of motion-induced wind forces by the suggested method agree with forced vibration wind tunnel test values, and wind responses calculated by using these approximated motion-induced wind forces agree with aerodynamic model tests. 2) Unstable aerodynamic response could occur for base-isolated high-rise buildings with light structural density and low yield load of the lead dampers.

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