Dynamic Characteristics And Seismic Response Analysis Of Double Tower Concrete Cable-Stayed Bridge With Central Cable Plane

The central cable plane concrete cable-stayed bridge has the characteristics of simple shape,wide driving vision,moderate spanning ability and relatively low cost.Under certain construction conditions,it has strong competitive advantages and is widely used in China.However,in recent years,earthquakes occur frequently at home and abroad,and earthquakes with large magnitude occur frequently at home,which not only cause great damage to urban buildings and infrastructure,but also cause great damage to bridges as lifeline projects.Therefore,the study of the dynamic characteristics and seismic response of the central cable plane concrete cable-stayed bridge has practical significance for seismic design.Based on the engineering background of a central cable plane double tower concrete girder cable-stayed bridge with a main span of 360 m in Fengkai County,Zhaoqing City,this paper uses the finite element analysis software Midas/Civil and SAP2000 to establish the spatial finite element model of the main bridge,compare and analyze the structural dynamic characteristics of the main bridge,and then conduct response spectrum analysis and time history analysis of the main bridge,and summarize the seismic response characteristics of the central cable plane double tower concrete cable-stayed bridge.The main work of this paper is as follows:(1)This paper introduces the development of cable-stayed bridges,the structural characteristics of central cable plane cable-stayed bridges,the seismic damage of bridges and the seismic characteristics of cable-stayed bridges,briefly describes the evolution of bridge seismic design methods,and clarifies the background and significance of the topic.(2)Briefly describe the structural structure characteristics,design parameters and modeling principles of the main bridge.Under the consideration of pile soil structure action,two different finite element software are used to analyze the dynamic characteristics of the main bridge,compare the first ten vibration modes respectively,and analyze the vibration mode orders that need to be considered to meet the quality requirements of the specification when using the multi mode response spectrum method to calculate.(3)The response spectrum method is introduced.According to the site type and seismic fortification target of the bridge site where the main bridge is located,the response spectrum seismic response analysis of the main bridge under six working conditions of E1 level and E2 level is carried out respectively,and some useful conclusions are drawn.(4)The basic theory of time history analysis is introduced.Combined with the site conditions,the acceleration time history with different characteristics is selected to analyze the uniform excitation time history of the main bridge.Under E1 level,the results of linear time history analysis and response spectrum analysis are compared;Under the E2 level,the equivalent yield moment of the key section is calculated by using the moment curvature curve,and the capacity demand ratio of the key section is calculated.At the same time,the nonlinear time history analysis considering elastoplasticity is compared with the linear time history analysis not considering elastoplasticity.The results show that each key section of the main bridge meets the seismic performance requirements.