Seismic Analysis Of Large Span Steel Truss Bridges And Frictional Pendulum Bearings

The large span steel truss bridge which is constructing in Weifang is located in the Tanlu earthquake zone.The analysis of the bridge’s seismic performance is a major factor affecting.In this thesis,the response spectrum analysis and time-history analysis are conducted for the bridge which uses frictional pendulum bearing(FPB)as isolation unit.The responses of the bridge before and after the failure of the FPB bearing are compared.The main results are presented as follows:1.In order to simulate the mechanical properties of FPB precisely,an isolation element module is developed based on the RASPS simulation platform built previously,which considers the bi-directional coupled model with the variation of vertical load.An uni-directional displacement controlled testing,bi-directional displacement controlled testing,a shaking table testing of FPB under uni-lateral seismic excitations and bi-lateral seismic excitations are simulated using the developed module of RSAPS.The results show that the simulation can well validate the experimental data and conclusions.2.The response spectrum analysis and the time-history analysis for the large span steel truss bridge is conducted by using MIDAS.The response of the bridge before and after the broken of the bolts in bearings are compared.According to the analysis,the conclusions are drawn as follows: the bridge works flexibly under earthquake E1 and E2.The bolts in FPB will break under earthquake action E1 and E2,and the bridge is controlled by the seismic restrainers while sliding laterally.The truss bar and the piers are elastic under the earthquake and the displacement of the bearing is within the limitation.3.Two finite element models are constructed using ABAQUS for the cases with and without considering the broken of the bolts in FPB.The time history analysis is conducted and the structure response has been compared for the models.The truss bar and concrete pier do not yield under earthquake action E1 and E2,and the displacement of the bearing is within the limitation.It is more proper to make nonlinear time history analysis considering the FPB isolation mode.