Study On The Seismic Damage Prediction Of Reinforced Concrete Bridge Based On Time-varying Properties Of Materials

With the economic development,the network system of traffic has also developed rapidly.By the end of 2017,there have been more than 800 thousand highway bridges nationwide.The earthquake damage experience of the Haicheng earthquake and the Tangshan earthquake indicating the bridge is the most vulnerable part of the highway system at the time of earthquake.Besides,the bridge is in a key position of the transportation hub and China is the Earthquake-prone zone.Therefore,in this paper,a reinforced concrete bridge is taken as the research object.The nonlinear time analysis of the simulated object is analyzed,and the relevant analysis data is obtained to establish the vulnerability curve of the reinforced concrete bridge.In addition,time-varying characteristics of the steel and concrete materials under the two environmental conditions that are the general air environment and the coastal air environment are taken as considerations to establish the time-varying analysis model.According to the analysis data to map the vulnerability curve and obtain the earthquake damage matrix.The main research contents of this paper are as follows:(1)Based on the consideration of the carbonation of concrete and the erosion of chloride ions,a preliminary summary of the time-varying formula of the strength,elastic modulus,carbonization of concrete and steel reinforcements under the coastal atmospheric conditions and the general atmospheric conditions is proposed.(2)Summarizing the method of quantifying the damage index,and the displacement coefficient ductility coefficient is selected as a criterion of damage ratings.Establishing a simulation model of the research object to perform moment-curvature analysis and calculate the damage index under different damage conditions.The nonlinear time-history analysis of the model was carried out to establish the earthquake probability demand model and the fragility curve of the initial state of the model is drawn.(3)Based on the time-varying characteristics of concrete and steel,to predicting the seismic damage of reinforced concrete bridges.Calculating the time-varying data of the strength and the elastic of the concrete and steel on the basis of the time-varying formulas.Establishing the time-varying model under the general coastal atmospheric conditions and the general offshore atmospheric.The moment-curve analysis and the nonlinear time history analysis of these models are conducted respectively.According to the result of the analysis,calculating the damage index.The seismic probability demand model and fragility curve are established respectively.