Effect of damped outriggers arrangement on the seismic response of high-rise steel structures

Abstract

Recently, a novel structural system, which is defined as damped outrigger system, has been proposed to control dynamic vibration of tall buildings. This paper examines seismic performance of tall buildings involving multiple outriggers equipped with viscous dampers. In this respect, a dual structural system (braced moment frame) is selected as a bare structure. In addition, the number and position of outriggers are assumed to be variable along the height of structure. Nonlinear response history analysis (RHA) is performed to evaluate the efficiency of damped-outrigger system under eight scaled ground motions. The results are presented based on the average of all ground motions. The mean inter-story drift ratio and maximum base shear force are compared in order to determine the best arrangement of damped outriggers. Conclusively, based on minimizing base shear force, the optimal location of damped outriggers under dynamic excitation is generally the same as that made for conventional outriggers. According to the inter-story drift ratio parameter, it is recommended to place one of the outriggers at the roof level.