The Dynamic Performance And Anti-earthquake Analysisl Of Cable-Stayed Arch Bridge

With the development of society and economy,as well as the emergence of new materials and new technology,people have put forward higher requirements in usability,security and aesthetics of bridge engineering.At the same time,considering the advantages and disadvantages of various bridge forms,combination of the advantages leads to the collaboration between bridge systems.Cable-stayed arch bridge is one of the newly emerging cooperative bridge system and there were little research done on this bridge type.Due to the fact that our country is in the middle of the world’s two major seismic belts,the Pacific Rim seismic belt and the Eurasian seismic zone,high-intensity earthquake occurred frequently.Bridges are susceptible to earthquake damages,and even more so for large bridges/ long span bridges or structurally complex bridges.The research background of this study-Xiangfeng River Bridge in Dalian-is the third cable-stayed arch bridge in the world,which contains inclined tower cable-stayed bridges without back-stays and heteroideus arch bridge.The work done in this paper is of great significance to supplement the study of the dynamic and seismic performance of cable-stayed arch bridge.In this paper,the finite element software Midas Civil is used to establish the spatial analysis model of Xiangfeng River Bridge.With respect to underground infrastructure,Pilesoil effect was considered.The following are the main contents of this paper.The dynamic characteristics of the bridge were analyzed by calculating the vibration period,frequency and vibration characteristics.The influencing factors of the self-vibration characteristics of the bridge was studied by adjusting parameters such as boundary condition,stiffness of the main beam,rigidity of the tower,the length of concrete in the arch rib and the inclination of the tower.Comparing the results of different Eigen value methods,we can analyze the coefficient of structural modal participation to ensure that more than 90% of the mass participation coefficient.According to the engineering conditions,the response spectra of horizontal and vertical design under the action of E1 and E2 are generated,and the structural response spectrum analysis was carried out by CQC mode combination method.By inputting the adjusted EL-centro seismic wave in three orthogonal directions in the model,considering Rayleigh damping in the calculation and using Newmark method to solve the problem,timeresponse of the structure under one-dimensional earthquake and multi-dimensional earthquake was analyzed.By comparing the time-response results of one-dimensional and multidimensional earthquakes the behavior of the bridge under the action of earthquake was summarized.Based on the concept of structural vibration control design,considered the influence of time-history response,the time-response parameters of the structure were analyzed.The seismic support,the elastic modulus of concrete,the length of concrete in the arch ribs and the inclination of arch bridge were studied.Comparative analysis was conducted on the effects of structural vibration control damping.Structrual anti-seismic response was verified.The elasto-plastic time-history response of the consolidation position of the tower girder pier was analyzed by defined elastoplastic material and fiber hinge.The fundamental frequency of Xiangfeng River Bridge in Dalianis small,and the overall stiffness is low.The transverse stability of the bridge is poor.The ratio of in-plane and out-ofband fundamental frequency is only 1.8124/0.5038.The upper and lower structure of seismic verification can meet the requirements of seismic fortification.There is no plastic damage in the consolidation position of the tower beam pier.