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The purpose of this paper is to investigate turbulence effects on characteristics of local severe suction on side face of a three-dimensional square cylinder by LES. The behavior of conical vortices associated with local suctions at the angle of the attack =0, and glancing angle are focused on. First, the computed results for distribution of the pressure coefficients are validated through comparison with the experimental data. Next, using the computed results, the effects of inflow turbulence on the high peak suctions and flow characteristics are examined. As a result, high peak suctions occur associated with wake characteristics and flow reattachment characteristics affected by the large scale fluctuation of oncoming turbulence.

In order to validate the LES(large eddy simulation) model for strong wind in actual urban area, this research performs the direct comparison between wind data estimated by LES and full-scale measurement data. Generally, LES cannot evaluate the absolute wind velocity, but can only a relative value to the reference wind velocity. In order to introduce the absolute value, we employ the meteorological model(MM5). In this study, first, based on the observation data on the rooftop of the high-rise buildings and several surrounding ground-level points, we clarify the flow characteristics of strong winds during cyclogenesis. Second, we numerically simulated the mean wind speed and the maximum instantaneous wind speed and validated the LES method through the comparison with the observation data. Accordingly the applicability of the present LES model for an actual shape of urban area has been clarified.

When a building with viscoelastic dampers is subjected to wind excitations, its dynamic properties such as vibration period and damping ratio can vary, depending on the frequency contents of the excitation. This is due to frequency sensitivity of the viscoelastic damper, and contradicts with the basis of the conventional spectral or modal analysis method using the constant dynamic properties evaluated at resonant state of the building. This paper points out the need for considering frequency sensitivity of a building when it possesses velocity-dependent dampers such as viscoelastic dampers, and proposes for the first time a new spectral or modal analysis method to predict the wind-induced response, considering the frequency sensitivity of the viscoelastic damper.

The measurement wind velocity on the rooftop of the tall building is usually utilized as a reference wind velocity. However, after many new tall buildings have been constructed around the specified tall building, it becomes difficult to use the rooftop data as a reference. While, the wind velocity predicted by the meso-meteorological model (MM5) without the urban-canopy model has been little affected by surface shapes of buildings on the ground and expected to be accurate at sufficiently higher position. This paper examines the regional representativeness of MM5 wind velocity data by comparing the full-scale measurement data at open area. Also, in the case of measurement point within the urban canopy, rooftop wind velocity computed by large-eddy simulation (LES) is estimated by matching MM5 wind profile. The method determining an appropriate height for a reference wind velocity is provided.

It has been recognized that the viscoelastic damper is effective against not only seismic force but also wind force. However the effect of viscoelastic damper on the wind-induced response has not been fully comprehended. This paper discusses the wind-induced response characteristic of tall building having the viscoelastic dampers based on time-history analysis results using the fractional time-derivative model. In addition, in order to clarify the effect of frequency sensitivity of viscoelastic damper to the wind-induced response of building, time-history analysis results using Kelvin model and/or Maxwell model are compared with the fractional time-derivative model.