The feasibility and effectiveness of the semiactive control system with Magnetorheological (MR) dampers by the proposed continuous sliding mode control are studied for decreasing seismic displacements of isolated bridges behaving linearly or hysteretically through shaking table tests. A two-story shear-type structure was designed to experimentally simulate the seismic response of typical isolated bridges. The MR damper based on the Bingham model can satisfactorily trace the desired control force with piecewise constant current input. Experimental and analytical results demonstrate that the semiactive control system is effective and superior to passive-on and passive-off systems in decreasing seismic displacement response of isolated bridges.
