Residual Performance of Hollow RC Piers Damaged by Rockfall Impact

Recently, hollow reinforced concrete (RC) piers have been increasingly utilized in bridge structures located in mountainous regions, owing to their high strength-to-mass ratio and stiffness-to-mass ratio. Among various natural disasters, rockfall poses a major threat to the serviceability and safety of bridge piers, potentially leading to a reduction in bearing capacity or even complete collapse. Given the critical nature of repairing or reinforcing bridges, this paper aims to enhance the understanding of the residual performance of hollow RC piers against rockfall impact. A simulation framework for hollow piers subjected to rockfall impact is developed using LS-DYNA and validated against available experimental data. Utilizing this validated framework, extensive numerical simulations have been conducted to investigate the effect of various parameters such as impact energy, longitudinal reinforcement ratio, stirrup ratio, and axial force ratio on the localized damage patterns and residual capacity of hollow piers. In addition, the relationship between the rupture width of the front panel and the resulting reduction in axial capacity is discussed. These results indicate the impact force and resistance mechanism of hollow piers are governed by the interaction between the rockfall and hollow section. The rupture width of the front panel notably increases with the impact energy, and increasing the stirrup ratio could reduce the concrete spalling. However, the axial force demonstrates minimal influence on the localized damage of the front panel when the rockfall diameter is less than the front panel width. The residual capacity of an impact-damaged hollow pier mainly relies on the rupture width of the front panel. These findings would contribute to the fast prediction of the residual capacity of hollow RC piers after rockfall impact.