Seismic vulnerability analysis of bridges incorporating scour uncertainty using a copula-based approach

Abstract

Scour can significantly compromise bridge foundations and increase the possibility of failure during seismic events. Although the traditional cloud method is a commonly employed approach for assessing seismic resistance in bridges subjected to scour, it relies on empirical assumptions and inevitably introduces analytical errors. A copula-based approach was proposed for seismic vulnerability analysis by incorporating the uncertainty of scour depth into the assessment of bridge seismic performance. A bivariate copula function was employed to model the nonlinear dependencies between intensity measures (IM) and engineering demand parameters (EDP), thereby facilitating the construction of more accurate vulnerability curves without the restrictive assumption of a log-normal distribution. The uncertainty in scour depth was captured using the Latin Hypercube Sampling (LHS) technique. A case study of a four-span continuous beam bridge was conducted to demonstrate the effectiveness of the proposed framework. The results indicate that scour has a significant impact on piles compared to other components. Taking the slight damage state as an example, as the scour scenario progresses from slight to severe, the failure probability of the piers and bearings under an IM of 1.0g decreases by 0.17% and 0.11%, respectively. However, the vulnerability of the piles increases by 9.78 times.