Performance Assessment of Corroded Reinforced Concrete Structure Considering Bond Deterioration

Abstract

This paper presents an assessment of the lateral load capacity and ductility of a 21-year-old reinforced concrete (RC) structure situated in a marine environment and affected by rebar corrosion. Nonlinear pushover analysis is carried out for the structure by modeling the hinges. The consequence of corrosion is accounted for in the moment rotation characteristics of the hinges by considering the reduction in bond strength, loss of rebar diameter, and reduction in the mechanical properties of steel. The basic bond stress–slip relationship from an internationally established model code is modified to account for corrosion using a bond model. This bond model is used to obtain the hinge properties of the corroded rebar. The simplified beam macromodel developed considering these modified hinge properties due to corrosion is validated with four-point bending tests carried out on beams and similar experiments from the literature. Moreover, a simulation is also carried out using a two-dimensional finite element micromodel of a beam using the modified bond model for the rebar affected by corrosion. The load deflection characteristics of the micro and macromodels are found to agree well for the four-point bending load for different levels of corrosion. The proposed beam model, considering the effect of rebar corrosion, is used for evaluation of performance of the 21-year-old corroded RC structure for the design basis earthquake load. Subsequently, a seismic assessment methodology is proposed for corroded RC structures.