Shaking table tests of a scaled bridge model with rolling-type seismic isolation bearings

Concurrent with the growth of the application of the seismic isolation technique to civil structures, a large variety of isolation systems has been developed during the past two decades. This paper investigates the seismic behavior of a 1/7.5 scaled bridge model isolated by rolling-type bearings. Shaking table tests of the scaled bridge model have been conducted to verify the effectiveness of the rolling-type bearing as a seismic isolation device. Test results reveal that the seismic force transmitted by the rolling-type bearing is independent of the earthquake intensities when the sloped rolling mechanism is completely triggered. An approximate expression is derived for predicting the peak acceleration response of a structure isolated by the rolling-type bearing. It is shown that the maximum structural acceleration may be estimated by the proposed formula. As an appropriate option, viscous dampers may be incorporated to reduce the larger displacement and eliminate unfavorable oscillation of the bridge deck, which may occur under strong earthquakes.