A Study On Serviceability Of FPS In High Speed Railway Simply Supported Girder Bridges Under Near-fault Earthquake

Friction Pendulum System(FPS)is widely used for its superior isolation effect.FPS has large vertical stiffness,very good durability and self-reset function after earthquake,so it has good application prospects in seismic isolation design.Since high-speed railway bridges inevitably span fault zones in earthquake-prone areas,it has some practical significance to study the serviceability of FPS in high-speed railway simply-supported bridges under near-fault earthquakes.The main contents are as follows:(1)Based on a large number of domestic and foreign literature,analysis of research status of FPS applied in high speed railway simply supported girder bridges,and the structural characteristics of CRTS ? ballastless track and the research status of its mechanical properties were introduced.(2)The calculation model of FPS isolation simply-supported girder bridge for CRTS? ballastless track was established by OpenSees.The influences of ballastless track constraint and the energy consumption of ballastless track line on seismic response of structure were studied.The results show that the ballastless track constraint has a great influence on seismic response of structures.The CRTS ? ballastless track can reduce the displacementsof the girder and the top of piers and the shear at the bottom of piers;Without considering the energy dissipation of the ballastless track,the displacements of the girder and the pier top,the shear force at the bottom of piers,and the energy consumption of the FPS are reduced,the result is smaller than the actual calculated results.(3)The safety evaluation of high-speed railway FPS isolated simply-supported beam bridge under multi-event earthquakes was made in this paper.The results show that considering the full train load and or not,the parallel turning angle and the turning angle of the ballastless track all meet the specification limit,but the beam misalignment does not meet the specification limit.(4)The main influence parameters FPS friction coefficient and radius of curvature were select by the orthogonal test,the purpose of optimizing the structure is to study the influence of the main influence parameters on the safety of the FPS isolatied simply-supported beam bridge with high-speed rails.The results show that the changes of FPS friction coefficient and radius of curvature have a great influence on the end dislocation,parallel rotation angle and turning angle of structural beam,but the beam end dislocation still cannot meet the specification limit.(5)The effects of FPS friction coefficient and radius of curvature on the seismic responses of FPS isolated simply-supported beam bridges were compared under far-field and near-field ground motion.The results show that compared with far-field earthquakes,the displacements at the top of the pier and the shear force at the pier top are more sensitive to changes in the radius of curvature of the FPS subjected to the longitudinal far-field earthquakes.Under transverse near-field excitation,when the radius of curvature of FPS is less than 2 m,FPS radius of curvature is more sensitive to the displacement of the pier and the shear force at the bottom of the pier,and the displacement of the bearing and the deflection of the end of the beam are more sensitive to changes in FPS friction coefficient compared with the far-field earthquakes.