Load-reduction performance of a novel fairing measure for bridge piers in tandem under dam-break waves

Bridge piers are highly vulnerable to tsunami-induced loads, yet universally applicable mitigation strategies remain limited. This study integrated flume experiments with high-fidelity computational fluid dynamics (CFD) simulations to evaluate the load-reduction performance and hydrodynamic behavior of a novel streamlined bridge pier fairing under dam-break wave impacts. The fairing simultaneously mitigates impulsive and quasi-steady loads by inducing wave-front separation and generating a distinct wake flow pattern. Under dry-bed conditions, overall process loads are reduced by 35.7 %–53.7 %. In wet-bed scenarios, impulsive peak loads decrease by over 15 %, with maximum reduction up to 30.4 % under large wave height. A tandem pier configuration, with the fairing placed upstream and a circular pier downstream, was examined to investigate the potential influence of the fairing's unique hydrodynamic wake recovery and interference effects. Compared to a dual circular setup, the upstream fairing reduces its peak load by 25.8 %, further lowering the downstream pier's load by 17.3 %, and diminishing the pier spacing sensitivity. Energy dissipation analysis confirms the fairing's enhanced resistance to extreme hydrodynamic loading and demonstrates superior performance over conventional spacing-based mitigation strategies. The fairing serves as a rapidly deployable auxiliary structure that enhances pier resilience under extreme wave loads without altering the primary load-bearing system. Its streamlined geometry induces characteristic wake interactions, providing theoretical insights into both the load-reduction mechanisms and potential secondary impacts on nearby structures for future design strategies.