Study On Longitudinal Pushover Analysis Of Long-span Cable-stayed Bridges

Seismic design is one of the significant aspects of bridge design. With the growing demands of structural performance, seismic design has made great progress. Based on the previous study and the shortcomings of the existing seismic methods, several corrections have been made in this paper by using the FEA methods. The main contents are listed as follows:1) Study on selection of seismic motion inputs of beam bridges. Among the many problems in timehistory analysis, the seismic motion input stands first. Based on the summary of former study and shortcomings, a method that the seismic motion input method is based on the mode participation mass ratio to choose the control range in the PEER database is given. Taking a three-span continuous beam girder as background, seismic analysis is made in the way above. The results show that the discreteness is little and coincides better with the results of response spectra analysis.2) Principles of pushover and reliability of using FEA software. The principles of pushover are stated and combined with the theory of response spectra, MPA is carried on using SAP2000. The results of a simple numerical example show that elastic pushover analysis and response spectrum method are highly consistent, thus verifying feasibility and reliability of pushover analysis using SAP2000. Later, elastoplastic pushover is carried on.The results show the relatively high accuracy between pushover analysis and timehistory method. Moreover, difficulties and key points of pushover analysis are illustrated.3) Study on pushover anaysis of long-span cable-stayed bridges and simplicity of model. Taking a long-span cable-stayed bridge for example, based on the last chapter theory and using MPA method, this paper makes the analysis and makes the modification of MPA to compare the differences of both models. Later, simplicity of the full bridge are done. Considering the equivalent nodal mass of the whole stiffening girder mass and diciding the position by comparing the dynamic behavior between simplicity model and the full bridge model, singletower model is obtained. Moreover, different types of seismic motion inputs are considered to verify the applicability of single tower model.