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Masuda K.,Fujita Corporation | Nakayama M.,National Institute of Technology,Oyama College | Ogawa T.,Tokyo Institute of Technology
Journal of Environmental Engineering (Japan) | Year: 2016

This paper proposes a reliability based design for limiting floor slab vibration due to human walk. The reliability index β can predict the stochastic vibration performance of any floor slabs, independent of the dynamic characteristics of floor slabs. The reliability design method was applied to an actual floor slab design and its validity was confirmed by hammering tests and a one person walking test using the actual building floor slabs.


Masuda K.,Fujita Corporation | Nakayama M.,National Institute of Technology,Oyama College | Ogawa T.,Tokyo Institute of Technology
INTER-NOISE 2015 - 44th International Congress and Exposition on Noise Control Engineering | Year: 2015

This paper estimates the vibration of floor slabs caused by people walking stochastically. Estimating the habitability index based on floor slab vibration due to human activity is important in designing steel structure buildings such as offices, shopping malls etc. But since the variation of this vibration can be large, its calculation can be difficult. This study attempts to evaluate floor slab vibration due to humans walking stochastically. Initially, full-scale measurements were carried out to determine the characteristics of vibration on a structure due to human walking. One or more people walked along a simply supported pedestrian corridor connecting two buildings in order to determine the statistics of Vvalues. The V-value is a 1/3 octave band peak spectrum of response accelerations corrected based on human perception. The distribution of the response V-values followed a lognormal distribution, with average values proportionate to the square root of the number of people walking, and variation coefficients reducing gradually as the number of people increased. In addition numerical simulations were carried out using the Monte-Carlo method with an improved, extended stochastic walk force model. It was clearly shown that the experimentally obtained results could successfully reproduced by using the Monte- Carlo simulation developed by authors. © 2015 by ASME.


Liu W.-G.,Shanghai University | He W.-F.,Shanghai University | Huo D.,Beijing University of Technology | Feng D.-M.,Fujita Corporation
Zhendong yu Chongji/Journal of Vibration and Shock | Year: 2010

Based on a single-mass model, the earthquake responses of isolation structures with different natural periods were analyzed by using the equivalent linearization method and the time history analysis method according to China, Japan and USA codes. Through comparison of acceleration response spectra, it was found that the response spectrum of the long period part of the design response spectrum in China code is too large. According to the results of time history analysis, the modified equation for the long period part was proposed based on the original acceleration response spectrum. Finally, the earthquake response of an isolation structure was computed by using the new modified acceleration response equation and the time history analysis method, and the results obtained with the modified long period response spectrum were consist with those of the time history analysis. The response analysis results showed that the proposed equation of response spectrum has higher analysis precision for isolated structures.


Sakai Y.,Hokkaido University | Sakai Y.,Fujita Corporation | Watanabe T.,Hokkaido University | Wasaki J.,Hiroshima University | And 3 more authors.
Environmental Pollution | Year: 2010

The roles of low-molecular-weight thiols (LMWTs), such as glutathione and phytochelatins, in arsenic (As) tolerance and hyperaccumulation in Pteris vittata an As-hyperaccumulator fern remain to be better understood. This study aimed to thoroughly characterize LMWT synthesis in P. vittata to understand the roles played by LMWTs in As tolerance and hyperaccumulation. LMWT synthesis in P. vittata was induced directly by As, and not by As-mediated oxidative stress. Expression of PvECS2, one of the putative genes of γ-glutamylcysteine synthetase (γECS), increases in P. vittata shoots at 48 h after the onset of As exposure, almost corresponding to the increase in the concentrations of γ-glutamylcysteine and glutathione. Furthermore, localization of As showed similar trends to those of LMWTs in fronds at both whole-frond and cellular levels. This study thus indicates the specific contribution of LMWTs to As tolerance in P. vittata. γECS may be responsible for the As-induced enhancement of LMWT synthesis. © 2010 Published by Elsevier Ltd. All rights reserved.


Ohno R.,Tokyo Institute of Technology | Wada Y.,Fujita Corporation
Communications in Computer and Information Science | Year: 2012

When we visit a complex public space such as a railway station or a large shopping mall for the first time, we must rely on guide signs to find our way. In crowded situations, we are called upon to read these signs while walking so as not to disturb pedestrian flow. The present study uses an immersive visual simulation system to examine the influence of observation conditions on sign detection and recognition. The experimental variables address the spatial layout of signs as well as the presence of other pedestrians. The results indicate some quantitative relationships between the above variables and readability and suggest effective layouts for signs in spaces where crowded conditions are unavoidable. © Springer-Verlag Berlin Heidelberg 2012.

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