Seismic performance assessment of bridges isolated by a new restorable cable-sliding bearing

Abstract

Although a large number of girder bridges use frictional flat sliding bearings to support bridge superstructures, these bearings may have excessive seismic displacement caused by strong earthquake due to the absence of the restorable ability. To improve the restorable ability, this paper presented a novel seismic isolation bearing based on flat sliding bearing and restorable cable restrainers, called Restorable Cable-sliding Bearing (RCB). The restorable cable restrainers in RCB are made up of steel cables and springs, which are used to limit large displacement and provide restorable forces for flat sliding bearings. In this paper, quasi-static tests were first conducted to study the seismic behavior of RCB, which was also used to calibrate analytical and numerical simulation methods. The effectiveness of RCB was then illustrated by a typical two-span reinforced concrete bridge. By comparing with flat sliding bearings, both nonlinear time-history analysis and fragility analysis were performed to study seismic performance of RCBs. Finally, a new factor based on the fragility difference between different components was also proposed to demonstrate the effectiveness of RCB on bridge system. It can be found that the proposed RCB can improve the restorable ability of flat sliding bearings, which can limit the excessive displacement and produce relatively small residual displacement under strong earthquakes.