Large Span Cable-stayed Bridge Seismic Analysis Considering Erect Stage

The traditional bridge structure is designed without considering the influence of the bridge’s construction sequence on the internal force and alignment of the bridge.When the bridge structure is simple and constructed with full scaffold,the construction sequence has little influence on the bridge,and the construction stage of bridge is more secure than the finished stage.With the development of economy,the span of bridge is longer and longer.Advanced construction techniques,such as cantilever hanging basket,are often used in construction,especially the long span cable stayed bridge will experience multiple system conversion during the process of cantilever hanging basket construction,which further leading to the internal force and alignment of the bridge is closely related to the construction process.Thus it is necessary to consider the construction sequence of the bridge structure in the structural design.Through the simulation analysis of construction process of long-span bridge,the internal force and alignment of each construction stage are obtained,then the internal force and alignment of the finished stage of bridge are solved accurately,which can be treated as the internal force under dead load in structure design.Besides the dead load of the structure,various kinds of loads such as earthquake load,wind load,vehicle load and temperature load are also need to be consider in the design of large span bridge structure.In this paper,only the seismic load effect and dead load effect are combined to illustrate the importance of construction process in bridge structure design.Other forms of load are not repeated as their calculation methods are the same with traditional design methods.The main contents of this paper are:1.Summarizes the development history and development status of seismic analysis of long-span bridges in China and abroad.2.The basic principle of simulation analysis of construction process is summarized.Taking a long-span cable-stayed bridge model as an example,the pivotal processes of finite element analysis of construction process simulation in Midas Civil such as finite element model building,load definition,construction plan and construction stage division are introduced.The influence of the construction process on the constant load internal force and deformation of long span cable stayed bridge is compared.3.The mode superposition response spectrum method is described,and the internal force and deformation of long span cable stayed bridge are calculated by this method.4.Through the combination of internal force and deformation under the action of earthquake load and the action of dead load,the influence of construction process on the internal force and deformation of the bridge is studied..5.At last,the research work of this paper is summarized,and the problems that need to be further studied and solved are pointed out.