Abstract:
The durability of older reinforced concrete (RC) structures is significantly affected by corrosion of the reinforcement and is a critical issue for New Zealand RC buildings because of the close proximity of most urban centres to a marine environment. Currently, the seismic assessment of such buildings is a challenging task because there is limited and dispersed guidance for how to assess the residual seismic capacity of corroded RC members and determine the likely overall seismic behaviour of an RC building exhibiting corrosion. An assessment procedure was developed to account for the effect of corrosion on the residual strength and deformation capacity of corroded RC members. Analytical models to predict material and member properties were considered and modified to account for pitting corrosion. These predictions were verified against a large database of experimental results from the available literature. A case study of a severely corroded RC building in New Zealand constructed in the year 1928 was assessed using the proposed methodology to investigate the reduction in seismic capacity due to corrosion. While no change in failure mechanism was found, the overall displacement capacity of the building was reduced by 25% compared to the assessed uncorroded condition. Finally, to estimate the changes in capacity and failure mode with respect to exposure time in a corrosive environment, the long-term corrosion effect was studied for the case study building assuming no remediation of corroded reinforcement. As a result, the displacement capacity was significantly reduced forming storey collapse at less than 1% drift, if no remediation was made after 30 years of continued corrosion deterioration.