Bridges in a changing climate: Fragility-based approach for evaluating the time-variant performance of bridges subjected to heavy vehicle collisions

Climate change exacerbates the structural deterioration of concrete highway bridges, posing a threat for them to resist vehicle collisions. However, the investigation into the safety of highway bridges under the joint effects of climate change, deterioration, and collisions caused by heavy vehicles is lacking. This paper presents a practical framework for assessing the lifetime fragility of concrete highway bridges exposed to both heavy vehicle collisions and climate change-accelerated corrosion. The main challenge of applying fragility-based approach in this framework lies in developing surrogate demand models, which traditionally requires extensive time-consuming simulations of vehicle-bridge collisions using finite element methods. To overcome this, an impact force time history model is proposed as an efficient alternative to represent collision demands on bridge piers by heavy vehicles. Implementation of this model has demonstrated a remarkable reduction of approximate 90% in computational time requirements compared to the collision analysis. The framework enables the generation of fragility surfaces at any given time throughout the bridge’s service life. The effectiveness of the framework is demonstrated using an example highway bridge, and fragility surfaces are generated for various climate scenarios. The results indicate a rise in the probability of collapse, from 0.4% for a structurally sound bridge to 87.2% after 80 years of chloride exposure when subjected to a heavy vehicle collision with an impact velocity of 100 kph and a truck weight of 36 t. Additionally, the impact of climate change is evident, further increasing this probability to 97.4%. These findings underscore the significant roles that both corrosion and climate change play in influencing the vulnerability of concrete bridges to heavy vehicle collisions. Addressing these factors in collision design and lifetime assessment is essential for ensuring the structural resilience and safety of bridges over time.