The wind characteristics of downbursts are significantly different from those of turbulent boundary layers. The non-stationarity, especially a severe moving downdraft and strong divergent outflow near ground, causes serious damage to buildings. In the past, few studies have focused on downbursts and downburst-induced wind loads on buildings. Therefore, the present study investigates the characteristics of downburst and its effects on buildings, based on two kinds of experiments using a pulsed wall jet and a moving wall jet. Special attention is paid to the effects of the non-stationarity of downburst on the wind pressure and force coefficients acting on buildings with flat and gable roofs. A brief discussion is made of the evaluation method of downburst wind loads on buildings.

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The conventional method for estimating total wind load by adding individual loads overestimates the wind load on a four-flue chimney supported by a hexagonal steel tower. Additionally, there are no design standards in practice to calculate the wind loads on hexagonal steel towers. In this study, wind tunnel tests were carried out to evaluate the wind loads on the four-flue chimney supported by the hexagonal steel tower and the following conclusions were obtained. Firstly, the base shear load and base moment of the cylinder calculated using the wind force coefficient obtained from the wind tunnel test results were about 37 percent and 38 percent smaller than the calculated value from the Building Standards Law. Secondly, the wind force coefficient on the hexagonal steel tower could be obtained from the wind tunnel test. In conclusion, a reasonable design load calculation method could be obtained from the wind tunnel tests on the four-flue chimney supported by the hexagonal steel tower.

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