VIBRATION CONTROL OF SUPER TALL BUILDINGS SUBJECTED TO WIND LOADS

Excessive vibration due to wind loads is a major obstacle in design an d construction of a super tall building. The authors recently introduc ed an innovative method for Controlling the wind response of super tal l buildings, which takes advantage of the so-called mega-sub structura l configuration. Preliminary investigation was performed under the ass umption that the wind load is a white noise and the building can be mo deled as a shear structure. In this paper, a more reasonable tall buil ding model (a cantilever beam) and a more realistic wind load model (a non-white stochastic process in time and space) are employed to desig n passive and hybrid mega-sub control systems and to examine the perfo rmance of such controlled buildings. Building vibration in both along- wind and across-wind directions is examined. The control parameters of the proposed systems, including the frequency ratio of the sub to the mega structures, the damping ratio of the sub structure, and the feed back gains of the actuator force, are studied and their optimal values are obtained. For comparison, a tall building without control and one with the conventional tuned-mass-damper control are also studied unde r the same load conditions. The significant cost-effectiveness of the proposed mega-sub systems is demonstrated in reducing the acceleration and deformation responses of tall buildings to wind loads, not only e nhancing the safety of structure and its contents but also improving t he comfort of occupants. (C) 1997 Published by Elsevier Science Ltd.