Influence of sliding threshold of hyperboloid friction pendulum bearing on seismic performance of simply supported beam bridge of high-speed railway

The existing research on hyperboloid friction pendulum bearing (HFPB) mainly focuses on the friction coefficient and curvature. However, the longitudinal gap between the top bearing plate and upper bearing plate reserved for adapting to temperature and other long-term deformation is also crucial to its seismic performance. Therefore, this article defines this longitudinal gap as the sliding threshold. On this basis, the finite element model of the whole bridge including HFPB is constructed and verified by the scale shaking table test, and then the influence of the sliding threshold on the seismic performance of the bearing is systematically analyzed. The numerical results show that with the increase of the sliding threshold, the efficacy coefficient based on the multi-index shows a non-monotonic change rule of ‘first rise and then fall’, and the comprehensive performance decreases after crossing the critical value. In contrast, under the transverse seismic input, the longitudinal relative displacement of the bearing is difficult to cross the gap, and there is basically no collision between the plates, and the influence on the efficacy coefficient can be ignored. In addition, by constructing the Gaussian process regression (GPR) prediction model, sensitivity analysis is carried out with ground motion intensity and bearing design parameters as input and efficacy coefficient as output. The results show that the sliding threshold is one of the key control variables affecting the comprehensive seismic performance. The research conclusions provide engineering guidance for the design of HFPB.