Research On Time-varying Seismic Performance Of Medium-small Span Bridges Considering Component Deterioration

As an important hub of transportation network,bridge engineering plays an extremely critical role in transportation system.However,the bridge also faces many external factors during its service,among which earthquake and deterioration of bridge components have great influence on the seismic performance of the bridge during service.Therefore,this paper takes a highway bridge in China as an example to comprehensively analyze the influence of the deterioration of bridge components on the time-varying seismic performance and vulnerability of small and medium span Bridges.The specific research contents include:(1)The time-varying deterioration constitutive model of steel and concrete materials in RC pier is established,and the time-varying deterioration mechanical model of plate rubber bearing is also established.The finite element model of the bridge is established based on Open SEES finite element program.7 seismic waves are selected for nonlinear dynamic time history analysis,and the influence rule of different rule deterioration analysis conditions on the dynamic characteristics and seismic response of the bridge structure is studied.The results show that with the increase of bridge service time,there are bearing shear stiffness increa se or decrease of main girder bridge to the degree of displacement response is bigger,the reinforced concrete pier degradation influence on the pier and abutment are bigger,the joint action of the influence on seismic response in most cases has amplification effect,a small number of cases have diminished role to each other.(2)Considering the influence of seismic wave unc ertainty,we select 100 seismic waves for nonlinear dynamic time history analysis,and establish time-varying seismic vulnerability models of pier column s,supports,abutments and other components based on probability reliability theory.Finally,considering the influence of failure correlation of each component,the law of seismic vulnerability of time-varying system of bridge structure is analyzed.The results show that: For bridge component seismic vulnerability model,as the bridge service time growth,pier damage probability increases gradually,pier bearing elevated to damage probability decreases to cross the bridge to the damage probability increases,and the abutment bearing elevated to vulnerability curve basic remain unchanged and cross the bridge to damage probability increases gradually,the abutment damage probability in passive direction increase trend.For the seismic vulnerability model of the bri dge system,the exceedance probability of the damage increases with the service time of the bridge.