Seismic Research Of Composite Girder Cable-Stayed Bridge Based On The Pushover Analysis

As important traffic base project, the long-span bridge is required to have good performance when the earthquake occurs. Therefore, it is of great significance to analysis the seismic performance of cable-stayed bridge rationally. As a convenient seismic assessment method, pushover analysis has been widely applied in building structures areas while it is rarely applied in composite girder cable-stayed bridge seismic analysis. A composite girder cable-stayed bridge with couple tower and couple cable is investigate to explore the applicability of pushover analysis in composite girder cable-stayed bridge seismic analysis..The main contents as follows:(1) Induction and summary of the earthquake damage of bridge and the development course of earthquake-resistance design was carried on. The introduction of basic principle and procedure of pushover analysis was made. In addition, the procedure of capacity spectrum to evaluate the seismic performance of bridge was described.(2) Based on element theory, a model of long-span composite girder cable-stayed bridge was built using Midas/Civil software. The principle and location of plastic-hinge was discussed. Incremental dynamic analysis was applied on the model to get the relation curve between the displacement of the controlling point and the shear in the foundation of the structure.(3) The three loading modes (uniform mode, inverted triangle mode and parabolic mode) were used to analyze the structure, by which the pushover curve could be got. By comparisons of pushover cures of incremental dynamic analysis and pushover analysis, it was verified that the three loading modes are inapplicable to seismic analysis of cable-stayed bridge. The modal pushover analysis can consider the distribution shape of modal and more modal. The result of modal pushover analysis is similar to those of time-history method, which verified the applicability of modal pushover analysis in the seismic analysis of cable-stayed bridge.(4) The modal pushover analysis was used to analyze the response of structure in different earthquake intensity with design code response spectrum. The seismic security of the structure could be evaluated using single parameter damage models.