Experimental studies on nonlinear seismic control of a steel–concrete hybrid structure using MR dampers

This article presents experimental studies on the feasibility of nonlinear seismic control of a 3-story steel–concrete hybrid structure using magnetorheological (MR) dampers. The control strategies included passive-on control, passive-off control and semi-active control, and strains gathered at the bottom of the steel columns were used as feedbacks to build the semi-active controller. For each control type, the control efficacy on structural response and damage was verified for the El Centro, Taft and Tianjin earthquake with specified peak ground acceleration (PGA) of 0.2g, 0.4g, 0.9g and 1.2g respectively. The test results show that (1) it is feasible to control the seismic response of the steel–concrete hybrid structure using MR dampers; (2) structure with semi-active control and passive-on control perform better in the shaking table test considering the maximum inter-story drift, displacement time history and energy dissipation capacity, compared to uncontrolled structure and structure with passive-off control; (3) there is also more structural damage in the passive-off and uncontrolled cases, proving the effectiveness of MR dampers in damage control. In addition, an inverse calculation method for strain is proposed to effectively utilize the strains measured during the shaking table test to obtain the stress and material damage process at measured positions, using damage model of the steel and concrete material.