Time-dependent seismic fragility analysis of reinforced concrete columns subjected to chloride-induced corrosion

Abstract

This paper presents a stochastic methodology to perform time-dependent seismic fragility analysis for reinforced concrete (RC) columns subjected to chloride attacks. Numerical modelling methods considering the increasing variability of reinforcement mechanical properties were proposed based on the stochastic constitutive model for corroded steel bars. Depending on the finite element model validated by test data for uncorroded and corroded RC columns, two novel stochastic cases and a traditional deterministic case were introduced and then applied to pushover analysis, incremental dynamic analysis and seismic fragility analysis. The results of damage limit states (DLSs) determined by stochastic pushover curves indicated that the seismic capacity/DLSs for columns along the service life were time-dependent and followed lognormal distributions. The incremental dynamic analysis curves and seismic fragility curves implied that chloride-induced corrosion typically led to a substantial increase in the failure probability of columns. In comparison with the correlated stochastic method, considerable underestimations of component level fragility across different damage limit states were obtained using the deterministic approach, which highlighted the importance of accounting for the variability of mechanical properties of corroded steel bars in the time-dependent seismic fragility analysis.