Abstract
One characteristic of modern tall buildings is that the building shapes are irregular and unconventional. The irregular and unconventional building shapes are resurrection of an old characteristic, motivated by new trends in architecture, but it has advantage of mitigating across-wind responses, which is a major factor in safety and habitability of tall buildings. Many studies on aerodynamic modification have been carried out, but most of the studies have forced on the corner modification, while the studies on taper and setback are limited. Changes of building shapes through taper and setback suppress the strong and periodic vortex shedding, and encourage the flow around a building more 3 dimensionalities, which results in reducing the wind-induced excitations. The results show that the reduction of mean along-wind and fluctuating across-wind overturning moments are apparent in the suburban area than in urban area. A series of the response analyses, the rms displacement responses of the tall buildings with height variations are reduced greatly, while the rms acceleration responses are not necessarily reduced. Lastly, the effect of different natural frequencies of tapered and setback tall buildings on wind-induced response are extensively discussed.