Seismic Robustness Analysis Based On Redundancy Theory Of Continuous Skewed Girder Bridges

Compared with the orthogonal bridge,skew bridge has a more complex seismic response characteristics.In China’s various types of bridges,skew bridge occupies a large proportion.How to choose a simple and effective evaluation theory for qualitative and quantitative evaluation of skew bridge seismic capacity is a hot research direction.Based on a three-span continuous skewed bridge in highway,using OpenSees software,the full-bridge finite element models with different skew degree and type of pier columns were established in this paper,the structural capacity demand curve and the seismic vulnerability curve were studied by Pushover and IDA methods,and the seismic robustness of the continuous skewed bridges was studied by referring to the redundancy evaluation theory in the building structures.The paper mainly carried out the following work:(1)Through the investigation of the seismic damage of the skewed bridges,the characteristics of the seismic damage of the skewed bridge and its own characteristics were summarized,and the basic theory knowledge of the redundancy theory and the structural seismic robustness were summarized.(2)The calculation method of redundancy and robustness-related indexes in the building structures were introduced,the issues need to be paid attention to when methods mentioned above applied to the continuous skew bridges were summarized in the paper.(3)Taking a three-span continuous skewed bridge in highway as an example,Pushover analysis and IDA analysis were carried out by using OpenSees software for modes with different skew degree and type of pier.Redundancy demand ratio r and the anti-collapse reserve coefficient CMR two indicators for evaluating the seismic robustness of the bridge were gained.(4)The change of the redundancy demand ratio r and the anti-collapse reserve coefficient CMR of the continuous skewed bridge with different skew degree and type of pier were analyzed.The results showed that the redundancy demand ratio r decreases with the increase of the skew degree,and increases with the number of the pier.At the same time,the anti-collapse reserve coefficient CMR shows the same trend as the redundancy demand r.And there was a linear correlation between the redundancy demand ratio r and the anti-collapse reserve coefficient CMR,which shows that the robustness and seismic performance of the continuous skewed bridges could be evaluated by the redundancy theory.