The present paper investigates the buckling and vibration behavior of cylindrical storage tanks based on wind tunnel experiments and FEM analysis. Focus is on the effect of the vibration of tank shells on the buckling behavior. The dynamic buckling loads obtained from the experiments are compared with those obtained from the FEM analysis for static wind loading. In the case of ring-stiffened tank models, the vibration of tank shell caused by wind fluctuations affects the buckling behavior significantly. On the other hand, in the case of free-edge tank models, the tank shell exhibits quasi-static buckling behavior. In addition, the dynamic buckling behavior of practical steel tanks is simulated by time history response analysis. The dynamic buckling load is found to be larger than the static buckling load. Therefore, the effect of the inertial force generated by the vibration of tank shell on the dynamic buckling behavior seems quite small. Quasi-static response is dominant in the buckling behavior. Finally, the dynamic buckling loads are evaluated based on the results obtained from the FEM analysis for static wind loading.
In this study, tornado-like flows under the horizontal shear flows whose types were one cell, two-cell, and multi-vortexes, were generated by Large Eddy Simulation with a real scale rectangular numerical field. As the results of investigation of the average tangential wind speed, it was found that Rankine’s vortex and Burgers-Rott vortex could not express the calculation results well. Therefore, assuming that the mean flow field was formed by the swaying vortex on the circle, the distribution of the mean tangential wind speed was calculated, and a new formula for the distribution of mean tangential wind speed was proposed. It was clarified that this proposed formula could fit to distributions of mean tangential wind speed for one cell, two-cell and multi-vortexes, very well.
It is well known that outdoor measurement of low frequency sound is affected by wind. The sound pressure data measured through microphone are contaminated by the pressure fluctuation by wind noise. Therefore, it is important to develop a method to estimate the sound pressure level of wind noise that would allow conducting measurements in continuously fluctuating natural wind conditions. In this paper, we have proposed an empirical formula to estimate wind noise in which frequency, average wind speed and turbulence intensity are the key parameters. Based on field measurement at several measurement site with different ground surface roughness, we have determined the values of coefficients required in the proposed formula as functions of the frequency. The appropriateness of the proposed estimation method have verified based on the results of field measurement. The proposed method have applied to the measurement of low frequency sound from existing highway bridges successfully.
Natural ventilation is an important factor in the design of a zero energy building. The design target should be discussed in the early stage of building design because building planning has a considerable influence on successful installation. Against this background, a target air change rate has been proposed for naturally ventilated building designs. In this paper, a map of the target air change rate in Japan is presented. It can be used as design data for architects to determine an effective natural ventilation strategy. It suggests that the air change rate can be set at approximately 4 ACH throughout Japan when the assumed internal gain is general. On the other hand, the target air change rates differ from north to south, and a successful installation can be realized more easily in cool regions than in temperate regions