Climate Change Impact on Seismic Vulnerability of Aging Highway Bridges

The lateral load-carrying capacity of highway bridges is adversely affected by corrosion deterioration of reinforced concrete (RC) bridge piers during earthquakes. Recent studies reveal that increased global warming due to climate change causes changes in temperature and humidity that further exacerbate the corrosion deterioration of RC bridge piers. This climate change-induced corrosion deterioration may further impair the performance of bridges when located in regions of moderate to high seismic zones. Consequently, this study provides a probabilistic framework for considering the joint impact of corrosion deterioration, earthquakes, and climate change on the lifetime vulnerability of highway bridges. The framework is demonstrated using a case study of a nonseismically designed highway bridge located close to marine sources within seismic active region of Gujarat, India. An improved corrosion deterioration model is utilized that incorporates climate change and concrete cracking effects for estimating time-dependent corrosion of the RC bridge pier. A robust, experimentally validated finite-element model is developed that can capture the varied failure modes of the bridge pier. A set of recorded ground motions that represents regional seismicity is selected to perform nonlinear time-history analyses. Time-varying damage state thresholds and probabilistic seismic demand models are used to develop seismic fragility curves for the bridge while also accounting for the climate change effects. Results reveal that consideration of climate change effects significantly increases the seismic fragility of the deteriorated bridge up to 53%. Lastly, the developed methodology is demonstrated for seismically designed bridge to evaluate the impact of modern codes for ductile detailing and durability provisions on bridge vulnerability incorporating climate change effects.