Response of Bare and CFRP-Retrofitted Multi-Column Piers Under Post-Fire-Coupled Vehicle Collision and Air Blast

Numerous catastrophic events, including fire, vehicle collisions, and air blasts, have highlighted the significance of examining bridge performance under multi-hazard scenarios. While these hazards cause extensive damage, the loss of life, and drastically impact economies, limited attention has been devoted to study the behavior of bridge structural elements under such extreme demand combinations. Hence, comprehensive research to understand the resiliency of bridges and their response to combinations of fire, vehicular impact, and air blast is warranted so that effective retrofitting techniques can be developed and design recommendations be made. To address this research gap, present investigations utilized previously validated finite element (FE) models in LS-DYNA to study the structural behavior of two-, three-, and four-column piers under post-fire medium truck collision and subsequent air blast. The response of multi-column piers was quantified and evaluated based on damage propagation, failure patterns, and permanent deformation sets. The effectiveness of selected retrofitting techniques that employed carbon-fiber-reinforced polymers (CFRPs) to mitigate damage was investigated. Study findings enhance current understanding, provide valuable insights, and can ultimately be used to ensure safety and improve the structural integrity of bridge piers under coupled vehicle collision and air blast following fire exposure.