Optimal MR Damper–Based Semiactive Control Scheme for Strengthening Seismic Capacity and Structural Reliability

Abstract

Semiactive control has received extensive attention because it can attain a similar control gain as active control while requiring a smaller external power supply. The critical step of semiactive control refers to the control parameter design and optimization in terms of a certain probabilistic criterion. However, the existing developments are limited in derivation of the statistical moments of quantities of concern, and knowledge of reliability of the controlled structure still remains open. This paper addresses the seismic reliability–based parameter optimization of magnetorheological (MR) dampers for structural control in semiactive modality under stochastic earthquake ground motion. An integral design scheme is proposed that implements the simultaneous optimization of (1) cost-function weights of active control, and (2) MR damper parameters of semiactive control. Comparative studies on probabilistic criterion, design scheme, and cost-function weight configuration are involved. It is revealed that reliability-based semiactive optimal control attains a safer and more serviceable structural system than the statistical moments–based semiactive optimal control; in addition, the integral design with simultaneous optimization of parameters allows a better balance between control gain and control demand than a previous separated design with sequential optimization of parameters. For verification purposes, a 6-story shear frame deployed with MR dampers subjected to stochastic earthquake ground motion is considered. The numerical example shows that the reliability-based integral design can ensure sufficient structural reliability in a global sense and accommodate smooth structural performance along the story level.