Engineering demand functions for medium-span RC bridges subjected to earthquake and scour actions

Abstract

In Mexico, there are two broad areas where highway bridges are subjected to multi-hazard action due to the effects of scour induced by floods and the occurrence of earthquakes. This study aims to determine, for the first time in the country, analytical expressions to assess engineering demand parameters of the joint action of earthquakes and scour events. These expressions will be the basis to evaluate expected losses and the risk of bridges located in these regions, to prioritize rehabilitation and reinforcement actions. Initially, a statistical analysis of the bridges' typology in the regions of Mexico exposed to multi-hazard was carried out. Based on those analyses, the geometric characteristics of the numerical models were chosen. Spectral acceleration in the longitudinal and transverse directions of the bridges was selected as the seismic intensity measure (IM), whereas engineering demand parameter (EDP) was the curvature ductility demand in columns (μφ). On the other hand, the expected maximum scour depth (ys) was estimated by evaluating the maximum extraordinary flood at bridge locations. Finally, IM-EDP empirical functions that correlate μφ−ys−Sa(T), based on 25020 nonlinear time-history analyses, were proposed. The proposed equations can also be used in other sites with similar bridges’ typologies subjected to multi-hazard actions of scour and interplate and intraplate earthquakes.