Studying the Effect of Fundamental Structural Period on the Seismic Fragility Curves of Two-Span Integral Concrete Box Girder Bridges

Abstract

The main step in deriving fragility curves of structures is to develop their probabilistic seismic demand model (PSDM). PSDMs can be expressed as the linear regression of engineering demand parameters and intensity measure suitable pairs in the log-transformed space. However, extracting PSDMs can be costly, computationally challenging, and time-consuming. For these reasons, this study proposes a practical method to estimate the two coefficients of the regression fit line of PSDM based on the fundamental periods of two-span integral concrete box girder bridges. Moreover, the effect of geometrical properties on the fundamental period has been investigated and an equation has been derived for the estimation of the fundamental period. For statistical analyses, 220 bridges are modeled using Latin hyper-cube sampling while 35,200 nonlinear time history analyses are done using OpenSees software to generate PSDMs.