Stochastic structural control under earthquake excitations

Abstract

SUMMARY Structural control is an alternative tool, which can be used for the reduction of the response caused by earthquake excitations. Research and implementation in practice have shown that seismic control of structures has not only a lot of potential but also many limitations. Many control strategies are based on the dynamic characteristics of buildings. During the life of the structures, these dynamic characteristics change. So there is a need of modifying the control algorithm. The question that arises is what would happen to the response of controlled structure if the parameters that influence the dynamic characteristics such as mass and stiffness would change while the control algorithm would remain the same. In this paper, this practical issue is discussed, using a stochastic control approach. The influence of the random character of the loads and the stiffness to the response of structures controlled by a modified pole placement algorithm are investigated. Loads and stiffness are considered as random variables, and the response of a structure subjected to dynamic loads is calculated using Monte Carlo methods (i) without control and (ii) controlled by the mentioned algorithm. The methodology is implemented for three characteristic buildings. The cumulative distribution function of acceleration, velocity, and displacement is obtained using the controlled and the uncontrolled analysis for the examined buildings. Deterministic results of the response are also calculated and compared with the random characteristics of the stochastic analyses. Conclusions regarding the influence of the variance of loads and stiffness to the response of structures are presented. Copyright © 2013 John Wiley & Sons, Ltd.