Ensemble Analysis of Climate-Change Impacts on Design-Service Life of Reinforced Concrete Bridge Decks across Canada

Abstract

This study presents a novel approach to investigate the impacts of temperature rise in a changing climate on the design-service life of reinforced concrete bridge decks in diverse regions across Canada. Most studies in the literature on service life prediction and service life design of concrete structures built in corrosive environments have not considered the effects of temperature and climate change on the key parameters that govern the service life of concrete structures, including concrete bridge decks, which is the focus of this paper. The future values of temperature are obtained by using an ensemble of 10 global climate models (GCMs) under three representative concentration pathways (RCPs) of future greenhouse gas concentrations, aerosols, and land use. The service life of concrete bridge decks is defined as the time to the onset of corrosion, which is assumed to follow a Fickian diffusion model, where the chloride diffusion coefficient and chloride threshold are temperature-dependent. The projected increases in temperature affect both the diffusion of chloride ions in concrete and corrosion mechanisms of steel reinforcement and lead to reduced time to corrosion initiation. The results show a 4% to 7% increase in diffusion coefficient per 1°C increase in the 30-year average temperature. The projected changes in the design-service life are analyzed up to the end of the 21st century. The ensemble mean shows 33% and 50% reductions in the design-service life of ordinary Portland cement concrete (OPC) and high-performance concrete (HPC) bridge decks, respectively. Considerable uncertainties from different sources contribute to the uncertainties in the projected changes of temperature and corrosion initiation time. In the short-term (period of 2021–2050), the uncertainty in the GCM provides the highest contribution to the uncertainty of the corrosion initiation time. Afterwards, the highest uncertainty is associated with the RCPs, which contribute up to 80% of the uncertainty in the design-service life in the last period of the century. The ensemble analysis also illustrates the distinct regional variations in the reduction of the service life due to the regional variation of the climate change impacts in Canada.