Seismic Fragility Analysis of Bridge System Based on Fuzzy Failure Criteria

Abstract

Inthetraditionalbridgeseismicfragilityanalysis,thecriterionforjudgingthestructuraldamagestateisclear.Thatistosay,when thedamageindexexceedsaspecificvalue,thestructureisjudgedtoenterthenewdamagestate.However,theactualconditionis that the boundary of structural damage is not clear but fuzzy. Taking a three-span V-shaped continuous girder bridge as an example,thedamageprocessofthestructureisdescribedbyfuzzymathematics.Consideringtheuncertaintiesofgroundmotion andstructureitself,aseismicfragilityanalysismethodisestablished,whichcanconsidertherandomnessofbridgeitself,seismic load,andstructuralfailurefuzzinesssimultaneously.Finally,theimprovedproductofconditionalmarginal(I-PCM)methodfor fragility analysis of bridge system is further optimized and improved. The new improved method is used to form the seismic fragility curves of bridge structure system. The results show that it is possible to underestimate the potential seismic fragility of bridge components and system without considering the structural fuzzy failure criteria; the fragility curves formed by different membership functions are obviously different; the new system fragility analysis method can significantly improve the analysis accuracy.