Impact performance of RC piers protected by closed-cell aluminium foam (CAF) of different thicknesses

Considering ship–bridge collisions can cause serious damage to pier components, we investigated the protective effect of closed-cell aluminium foam (CAF) on reinforced concrete (RC) piers. The effect of CAFs with different thicknesses on the impact resistance of RC pier specimens was studied by analysing the impact force, displacement, reinforcement strain, other dynamic responses of RC pier specimens, and the damage degree of RC piers using an ultrahigh drop hammer impact test system. The results show that the CAF material was in a linear elastic stage when the impact velocity was within 0.76 to 1.14 m/s. When the thicknesses were increased from 50 mm to 75 mm and 100 mm, the impact force and top displacements tested from the two groups of specimens showed an increasing amount of decline. The CAF material was observed to be at a yield platform stage when the value of the impact velocity was within 1.14 to 1.98 m/s. Under these conditions, the CAF material exhibited the best energy consumption and absorbed the impact energy in a nearly constant stress stage, while the impact force remained approximately constant. This study discovered that under high-energy impact conditions, CAF materials with larger thicknesses delayed entry into the densification stage, resulting in better control of the lateral dynamic responses of RC piers.