Stochastic Seismic Response Analysis Of Low-pylon Cable-stayed Bridges

As combined structure between rigid continuous beam bridge and the flexible cable-stayed bridge,Low-pylon cable-stayed bridge has been widely applied in recent years,studying the seismic response has practical significance.At present,the study of the dynamic performance of the low-pylon cable-stayed bridge is mainly based on the deterministic analysis of spectrum analysis and time-history analysis.However,the response of the structure under seismic action is a random process,should use the probability method to analysis the law.The thesis based on random vibration theory,taking Dongping waterway bridge as the research background,selecting a reasonable model of the power spectrum and spatial effect model to study multi-support multi-dimensional stationary stochastic seismic response,the main research contents are as follows:(1)The dynamic characteristics of the Low-pylon cable stayed bridge are studied and compared with that of the cable-stayed bridge and rigid continuous beam bridge with the same span.The results show that:the structural system,the boundary conditions,quality and rigidity of beam and pylon are the decisive factors of the dynamic characteristics of the Low-pylon cable-stayed bridge,and its dynamic characteristics are more close to the rigid continuous beam bridge.(2)Respectively analyzing the seismic response of Dongping waterway bridge on one-dimensional,two-dimensional and three-dimensional excitation,the results show that:the coupling effect of Low-pylon cable-stayed bridge under 3D seismic is very obvious,and sensitivity of each dimension earthquake for each part of the structure is not same.(3)Select a specific power spectral model and the corresponding parameters of the actual project,The effect of spatial effect(traveling wave effect,coherence effect and local site effect)under the stochastic seismic response of the Low-pylon cable-stayed bridge is analyzed,results show that:Three kinds of spatial effects have certain influence on the displacement and internal force response of the structure,and the degree of influence and law is not same.The traveling wave effect on the seismic response of the cable-stayed bridge is significant.(4)The effect of pile and soil,different ground motion model for random seismic response of Low-pylon cable-stayed bridge is analyzed,the results show that:the effect of pile and soil and the selection of power model on seismic response is relatively large,Du Xiuli model is more reasonable than the other models seismic response.