Dynamic behavior of double-column FRP-concrete-steel tubular bridge piers subjected to vehicular impact: Experimental study and numerical analysis

In humid and corrosive environments, FRP-concrete-steel double-skin tubular columns (DSTCs) have demonstrated significant potential as bridge piers. Vehicular collisions are a major cause of bridge pier failures during their service life. While existing studies on DSTCs under lateral impact loading have primarily focused on singlecolumn configurations, double-column bridge piers are commonly employed in bridge designs due to their enhanced resistance to overturning. These double-column piers may exhibit different impact resistance characteristics compared to single-column piers. However, there has been no experimental research to date investigating the dynamic behavior of double-column DSTC piers (DC-DSTCs) under vehicular impact. To address this gap, this study conducted experimental investigations on two large-scale DC-DSTC specimens subjected to vehicular impact. This study specifically examined key parameters such as the impact velocity, the void ratio of tubular DSTC pier, and the support provided by the adjacent DSTC pier. Experimental results illustrated that: (1) the DC-DSTC specimen exhibited localized damage at the impact position of the impacted DSTC pier, while an overall flexural deformation was observed in both the impacted and adjacent DSTC piers; (2) the impact force, global deformation and localized concave deformation increased with higher impact velocities; (3) under highspeed impact (around 5 m/s), a larger void ratio in the tubular DSTC pier resulted in more significant local dent deformation but reduced global lateral displacement; (4) when subjected to high-speed impact (around 5 m/s), the support of adjacent DSTC pier played a significant role on the dynamic behavior of DC-DSTC with a smaller void ratio, while has a limited influence on DC-DSTC with a larger void ratio. Subsequently, FE models were constructed and validated to accurately simulate the dynamic behavior of DC-DSTC specimens under lateral vehicular impact. Finally, a refined FE simulation of a Ford F800 medium truck colliding with a prototype DCDSTC bridge was conducted to study the effect of both vehicle velocity and vehicle mass.