According to limitations of traditional reliability analysis on the identification of failure pattern of isolated bridges,a distinguish method based on IDA analysis and Weighted RSR method,combined with improved Park Ang damage model,was presented to estimate the statistical failure pattern of isolated bridges,which could provide a basis for the optimization of structural design.A finite element model for an isolated continuous bridge with six spans was developed within the environment of opensees,and then analyzed to obtain a statistic failure pattern.The obtained failure pattern was compared with the weakest failure mode of the isolated bridge.The weakest failure mode was optimized by selection of an optimal flexion weight ratio.The results showed that the isolation bearings on middle pears fail firstly,and all the bearings fail before piers.The optimal flexion weight ratio of this isolated bridge was 7%,which made the failurePGAincreased by 0.05g.
