Resilience‑oriented impact mitigation of RC bridge girders using aluminium honeycomb energy absorption

Civil infrastructure, particularly bridges, are increasingly vulnerable to hard-body impact events, such as vehicle collisions, vessel impacts, and debris strikes, which often result in safety-critical damage and extended service disruptions. This study presents a system-level investigation to leverage the well-established energy-absorption characteristics of aluminium honeycomb cushions for mitigating the medium-energy hard-body impact effects on reinforced concrete (RC) bridge girders. The honeycomb material is first characterized through staged quasi-static, high-strain-rate, and drop-weight impact tests to establish baseline mechanical behaviour and inform large-scale applications. System-level validation is conducted using a full-scale dual-T girder configuration that captures inter-girder interactions. The girder system is subjected to identical pendulum impact demands, with one girder protected by the honeycomb layer and a companion girder left unprotected. Complementary finite-element simulations, benchmarked against experimental results, reproduce measured force histories and provide further insight into stress-strain distributions and damage localization. Results are interpreted using a performance-based framework linking hazard (impact loading), demand (structural response), capacity (damage/failure states), and post-impact decision-making (resilience). Under identical impact conditions, the unprotected girder experiences catastrophic punching shear failure, corresponding to a safety-critical ultimate limit state (ULS) that requires reconstruction-based recovery. In contrast, the honeycomb-protected system reduces force transfer and absorbs or redistributes impact energy, which preserves serviceability and reduces the post-impact response to inspection-driven decision-making. These findings demonstrate the potential and supports the resilience enhancement of bridge infrastructure.