A SMA-based sliding friction damper for enhancing the transverse seismic performance of isolated bridges

Abstract

The concrete shear keys, serving as the transverse displacement-limitation component between the superstructure and the substructure of the bridges, are prone to be damaged during the strong earthquakes. The use of the isolation bearings can mitigate the seismic responses of the bridge piers, but their excessive transverse deformation is also prominent and consequently can cause the complete failure of the shear keys. Aiming at enhancing the seismic performance of the isolated bridges under very rare earthquakes, a novel SMA-based sliding friction damper (SSFD) is proposed and simulated, which combines the SMA cables with the sliding friction mechanism. The hysteretic model of the SSFD is derived from theoretical analysis, and realized and verified through OpenSees. The design method is also proposed to determine the mechanical parameters of the SSFD so as to meet the seismic mitigation demand under very rare earthquakes. The verification study is then conducted to check the design method and evaluate the effectiveness of the SSFD in control the excessive displacement between the deck and the piers of an isolated bridge. The results show that the proposed novel SSFD can effectively reduce the bearing deformation with the mechanical parameters determined by the design method.