Dynamic responses and damage behavior of hollow RC piers against rockfall impact

Abstract

Rockfall impact on bridge piers poses a challenge to the safety of bridge structures in mountainous regions. Hollow reinforced concrete (RC) piers are one of the popular constructional elements in engineering construction, and their impact behavior has not been fully investigated. Therefore, this study aims to explore the dynamic responses and damage behavior of hollow RC piers under rockfall impact. A finite element (FE) model of a hollow RC pier is established and validated against experimental tests. The validated model is then utilized to investigate the impact force, lateral displacement, internal forces, and failure mode of the hollow pier under rockfall impact. A parametric study is conducted to examine the effectiveness of rockfall diameter, impact velocity, axial force, impact elevation, and reinforcement ratio on the dynamic responses and damage modes of hollow piers. The results show that hollow piers under rockfall impact are prone to suffer serious localized damage with concrete spalling at the front panel, which plays a significant role in the pier’s global response. The stress distribution of cross-sections near the impact position is governed by the stress wave propagation and sectional internal force. Increasing the rockfall diameter would change the resistance mechanism of the front panel and enlarge the peak impact force (PIF) due to the influences of side panels and impact energy. The effects of impact elevation, axial force ratio, and reinforcement ratio are marginal on the impact force but significant on the lateral displacement and damage of hollow piers. This study provides a comprehensive understanding of impact performance of hollow RC piers and offers useful insights for their design and protection against rockfall hazards.