Nonlinear Damage And Seismic Performance Assessment Of Highway Bridge Under Strong Earthquake

Bridges are important links connecting transportation routes, they are alsoinfrastructures for social and economic development. With the urban populationincreasing, urban traffic pressure is becoming bigger and bigger, the role highwaybridges played is more important. In recent years, earthquakes happen continuously,which brings serious tests to highway bridges. Under strong earthquake, bridges gointo nonlinear states and failure process is complex. Due to lack of these issues, bystudying the damage evolution of highway bridge, establish the highway bridgedamage assessment system is necessary and has a certain significance for improvingdisaster prevention capacity of the bridge structure in China.Based on OpenSees, a nonlinear finite model of the bridge is established. Thispaper uses nonlinear dynamic analysis method to assess bridge damage state understrong earthquakes. The main contents and conclusions are as follows:(1) Establish three-dimensional nonlinear finite analysis model, specially focuson the main components of the bridge, such as bearings, abutments, piers andbeams.(2) Based on the existing studies, determine damage models of different comp-onents and use damage indexes to describe different damage states. Thedisplacement ductility ratio of columns and the displacement ductility of bearingsand abutments are selected as damage indexes.(3) Through nonlinear incremental dynamic analysis(IDA), the damage evoluti-on of the bridge under a series of strong earthquakes was investigated. Then IDAcurve between ground motion spectral acceleration and components’ damageindexes were drawn out. The results show the bearing damage is the most serious,the pier damage is second, serious damage to the abutment is difficult to occur.(4) Based on the existing component damage indexes, global damage assessme-nt method is proposed. Through combinations of components to determine theglobal damage state and choose the most unfavorable judgment. As the results show,global damage is more serious than any components’ damage. Under smallearthquakes bridges are basically intact or only minor damage, serious damagehappens under strong earthquakes.