Time‐Variant Seismic Fragility of Reinforced Concrete Bridge Piers Considering Degradation Phenomena

ABSTRACT Aging and environmental exposure progressively deteriorate the physical and mechanical properties of construction materials, thereby affecting the safety and functionality of existing infrastructure. Corrosion of steel rebars in reinforced concrete structures is widely acknowledged as the most common and detrimental degradation phenomenon, as it affects both the local and global structural performance. This issue is particularly relevant for the European bridge stock, which mainly consists of reinforced concrete bridges built in the last century, according to outdated design standards and using materials often not compliant with current requirements. As several infrastructural assets are approaching the end of their lifespan and require urgent retrofitting interventions, reliable tools for assessing their long‐term safety and seismic performance are urgently needed to support resilience‐informed infrastructure management. In this work, a probabilistic framework was proposed to assess the time‐variant seismic performance of archetype reinforced concrete bridge piers with different geometrical configurations, namely short and slender piers. The effects of degradation phenomena, including reinforcement corrosion, corrosion‐induced concrete cracking and creep were modeled through consolidated analytical formulations and implemented in a numerical model. Multiple Stripe Analysis was carried out to derive time‐variant fragility curves, aiming to assess the influence of degradation phenomena and their inherent uncertainties on the seismic performance of the pier. Seismic fragility evolution curves were also developed and presented herein, to provide useful tools in management frameworks. The results show that long‐term seismic performance is significantly affected by pier geometry and by the uncertainties associated with deterioration‐related input parameters, highlighting the importance of explicitly accounting for aging effects in seismic risk assessment of existing reinforced concrete bridges.