Updating the Seismic Reliability of Existing RC Structures in a Marine Environment by Incorporating the Spatial Steel Corrosion Distribution: Application to Bridge Piers

Abstract

Although several models are available for evaluating the structural performance of corroded reinforced concrete (RC) structures, seismic reliability assessments considering the effect of steel corrosion are currently scarce. Determining how long existing RC structures in an aggressive environment will be able to have a seismic safety level greater than the threshold remains difficult. Life-cycle reliability assessments of these structures under seismic hazards and hazards associated with airborne chloride are discussed in this paper. When predicting the seismic reliability of existing RC structures, observational data from inspection and/or nondestructive testing methods could be used to estimate the current material corrosion level. Considering the effect of steel corrosion in the plastic hinges of deteriorating structures on their seismic capacity is important. The displacement ductility capacity at the occurrence of longitudinal buckling of rebar in RC structures depends on the steel corrosion level in the plastic hinges. In this paper, the methodology to estimate the mean and variance of steel weight loss in the plastic hinge of corroded RC structures based on inspection results is presented. The number and space interval of inspection locations are considered when conducting the statistical estimation error process. The parameters to estimate the steel weight loss in the plastic hinges incorporating the spatial variability in steel corrosion are derived from experimental results to visualize the steel corrosion in RC members by X-ray technology. In addition, random variables associated with the prediction of time-variant steel weight loss are updated by sequential Monte Carlo simulations (SMCS) for consistency with the inspection results. The epistemic uncertainties can be reduced by SMCS. This process helps to conduct the reliability analysis more precisely. In this paper, a novel procedure for estimating the reliability-based life-cycle seismic reliability of existing RC structures in a marine environment by incorporating the spatial steel corrosion distribution is presented. In an illustrative example, the effects of the inspection results and frequency and the hazards associated with airborne chloride on the updated cumulative-time failure probability of a RC bridge pier in an earthquake-prone region are discussed.