Probabilistic demand assessment of bridges considering the effect of corrosion and seismic loading over time

Abstract

This paper proposes an approach to calculate demand hazard curves considering the effect of both corrosion and seismic loadings over time. The corrosion is defined as the reduction of the cross-sectional area in the reinforced bars of concrete, induced by chloride ions. Three corrosion phases are considered: starting time of corrosion, cracking, and evolution time. Seismic loads are characterized as a stochastic Poisson process. Uncertainties related to the randomness of geometric properties, mechanical properties, and seismic loadings are considered. The approach is illustrated in a continuous bridge designed to comply with a drift of 0.002. The structure is located in Acapulco, Guerrero, Mexico. Fragility curves and demand hazard curves are obtained at 0, 45, 57, 75, 100, and 125 years, based on the global drift. The effect of both corrosion and seismic loadings over time increase the annual rate of demand up to 308% between 0 years (without damage) and 125 years after the bridge construction.