Fragility Analyses of Bridge Structures Using the Logarithmic Piecewise Function-Based Probabilistic Seismic Demand Model

Seismic fragility analysis is an efficient method to evaluate the structural failure probability during earthquake events. Among existing methods, probabilistic seismic demand model (PSDM) and joint (JPSDM) are generally used compute component system fragility, respectively. However, statistical significance behind parameters related current PSDM JPSDM not comparable. Aside from that, when calculating Monte Carlo sampling (MCS) time-consuming. To solve two flaws, in this paper, logarithm piecewise functions were generate JPSDM, MCS was replaced by univariate conditioning approximation (UCA) method. The concepts application procedures of proposed methods elaborated first. Then, UCA illustrated detail. Finally, curves a steel arch truss case study bridge generated research results indicate following: (1) unify data sources JPSDM; (2) logarithmic function-based sensitively reflects changing trend component’s with fluctuation intensity measure; (3) under transverse waves, major injuries happen on side bearings bridge, while slight damage may occur each pier, as measure increases, more likely be damaged; (4) for severe absolute studied closer upper bounds; (5) compared MSC method, accuracy can guaranteed less calculation time.