A Study On Serviceability Of FPS In High Speed Railway Simply Supported Girder Bridges

The Friction Pendulum System(FPS) has good application prospect in seismic isolation design for high speed railway bridges because of it’s superior in isolation properties, durability, stability and repositioning after earthquake. It has important practical significance to study the application of FPS in high speed railway simply supported girder bridges, The main contents are as follows:(1) Based on numerous related literatures and reference at home and abroad, the characteristics of various common isolation devices were compared, and the current related research status on seismic isolation technology of FPS, effect of ballastless track restraints were summarized.(2)The calculation models of ballastless track, girders, piers and FPS in high speed railway bridges were researched, then a rail-bridge model was established which considers two common ballastless track respectively by OpenSees software. Moreover, the effect of ballastless track restraints on seismic response of high speed railway simply supported girder bridges isolated with FPS was analyzed. The results show that ballastless track restraints have great influence on seismic response of structure, application of CRTS II ballastless track slab decreases maximun displacement at top of pier, maximun displacement of FPS and provides isolation effect on track, it’s mean that CRTS II ballastless track slab should be firstly selected in FPS seismic isolation design.(3)The influence of various design parameters on structural usability under state of serviceability was studied by simulation of train load. The results show that high speed railway simply supported girder bridges isolated with FPS should be set FPS shear bolts which has enough large stiffness to meet the requirement of design standard for transverse natural frequency; moreover, the transverse linear stiffness of pier should also be enough large to attain satisfactory structural transverse natural frequency.(4)On the promise that structure satisfied the requirement of design tandard under state of serviceability, the vibration-suppressing effect of FPS was analyzed. The results show that FPS decreases longitudinal seismic response of structure but increases transverse displacement of superstructure, arrived at a conclusion that Linear stiffness of piers, frictional coefficient and radius of FPS have greater effect on seismic response of structure through the analysis of the design parameter.(5) Transverse displacement of superstructure in high speed railway simply supported girder bridges isolated with FPS can be reduced by transverse steel block installed at bottom of girders. The research demonstrates that steel block can effectively reduce the transverse displacement of superstructure, and increase displacement at top of piers at the same time. It’s necessary to rationally choose the parameters of steel block in design.