BENDING AND TORSIONAL VIBRATION OF TALL BUILDINGS IN STRONG WIND

In order to investigate the occurrence of vortex induced vibration, galloping and torsional flutter of tall buildings, the wind tunnel tests were carried out in smooth flow and turbulent boundary layer flow over urban area. Four models with rectangular cross section of which side ratios, D/B is 1/2 to 4 with aspect ratio, H/square-root BD of 10 were used in the tests where D is the depth in flow direction, B is the breadth normal to the flow and H is the height. The strong vortex induced vibrations were observed for the tall buildings with the shallow section both in the smooth and the turbulent flow. On the other hand, the galloping type vibrations were observed for the models with the side ratio of 2 and 3 in the smooth flow and the model of the square section in the turbulent flow. The torsional flutter were also observed for the model of the side ratio of 4 both in the smooth and the turbulent flows at the reduced velocity of U/n(t)D=6 where U is the flow velocity and n, is the natural frequency of the torsional vibration.