| China is an earthquake prone country,bridge structure under earthquake often suffered damage.Wall pier bridge is common in China’s municipal bridge,at present,there are some deficiencies in the research.The wall pier bridge as the research object in this dissertation,research on wall pier bridge damage mechanism and seismic vulnerability.The main works are as follows:(1)In this dissertation,the damage mechanism of the wall pier bridge is studied.Considering the particularity of wall pier,the seismic damage mechanism of the wall pier is studied.The experimental results of wall pier and shear wall structure are analyzed and summarized.Because the experimental data of the wall pier are few,and the shear wall are similar with wall pier,so the shear wall experiment are adopted.From the experiment we can see a wall pier in plane and out of plane exhibit different mechanical properties,and the mechanical properties of wall pier in plane are greatly affected by the structural parameters and axial compression ratio.Based on the understanding of the mechanical properties of the wall pier,this dissertation chooses the layered shell element to simulate the wall pier after comparing various finite element models.The accuracy of the model are verified by some instances.(2)Due to scarcity of experimental data and lack of understanding of mechanical properties of wall pier,the capability model of the wall pier is not studied in the previous studies.In this dissertation,the seismic performance level of bridge is determined by the previous research,and the displacement drift rate is used as the damage index of wall pier.Based on a survey of wall pier girder bridge,determining the structure parameters of the wall pier,the wall pier samples was established based on mixed orthogonal experiment design and finite element model is set up respectively,Through the hysteresis analysis,the displacement drift rate of the wall pier in the plane of the wall is obtained when the crack,yield appear and load capacity reach the peak and the limit state.According to the previous experience,the capability model is proposed,and the Bayesian method is used to estimate and eliminate the unknown parameters.Finally,the capacity model of the wall pier in plane is obtained.(3)Based on a benchmark bridge,considering the uncertainty of parameters,120 bridges sample is obtained through Latin hypercube sampling and the finite element model is established for every bridge.A total of 40 near and far field ground motions are scaled by a factor of 1,1.5 and 2.0 to have a suite of 120 ground motions.The bridge samples and ground motions were matched one by one for dynamic time history analysis.Finally,based on the lognormal assumption of the vulnerability function,the maximum likelihood method is used to obtain the seismic vulnerability of the wall pier girder bridge and its members. |
