Seismic isolation effect of a new type of friction pendulum bearing in high-speed railway girder bridge

Abstract

Residual displacement exists in the traditional friction pendulum bearings (FPB) under the action of earthquakes, which makes them fail to self-reset. In view of this, a new type of FPB called double concave friction pendulum with spring (DCFPS) is proposed. Firstly, the restoring force model and hysteresis characteristics of the theoretical DCFPS are derived. Then, the seismic isolation effect of the high-speed railway simply supported girder bridges (HRSB) equipped with the DCFPS is evaluated. Finally, the optimal spring parameters of the DCFPS are determined in terms of the efficiency coefficient and the optimal order method. The results show that the DCFPS has superior self-reset performance, and the hysteresis curve is “S” shaped. The stiffness of the DCFPS gradually increases with the swing displacement, which heightens the overall stiffness of the structure equipped with DCFPS. After HRSB is installed DCFPS, the displacement of the girder and the residual displacement of the DCFPS itself are reduced. The optimal stiffness and the initial tension of spring for the bridges exemplified in the paper are suggested as 3000 kN/m and 9 kN, respectively, through the efficiency coefficient method and the optimal order method. This research proposes a feasible solution for reducing the maximum displacement and residual displacement of bearings under an earthquake.