Seismic Fragility Analysis of Continuous Beam Bridge Based on Multivariate Copula Function

To solve the problem of low accuracy caused by only a single typical component, which is selected to represent the overall fragility in the traditional analysis, the bridge represented by continuous beam bridge was regarded as a ternary system composed of pier, abutment bearing and pier bearing. The damage degree of corresponding components was quantified by pier end curvature or damage index based on elastic-plastic energy dissipation rate difference and bearing displacement, and then the fragility analysis of components was carried out. Multivariate Copula function was introduced. On the basis of calculating the fragility curve of the main components, considering the correlation between the components, the corresponding joint probability density function was constructed, and the method to solving the seismic fragility of the ternary component system was established. The example analysis shows that the bridge system fragility based on multivariate Copula function can more truly represent the damage characteristics and fragility of the whole bridge and it can replace a large number of sampling analysis, which significantly improves the calculation accuracy and efficiency.