Experimental and numerical investigations on the impact response of precast segmental bridge piers subjected to soft and hard missile impacts

In recent years, a few experimental investigations on the impact response of precast segmental bridge piers have been reported. Although almost all of them have been conducted under hard impacts, the results have been used to predict and infer bridge piers' responses subjected to vehicle impacts. However, in reality, when a truck collides with a bridge pier, the pier is not only subjected to a hard impact from the engine but also to soft impacts from the bumper, cab, and cargo box. The stiffness of the impactor significantly affects the interaction between the impactor and bridge pier, which in turn affects the impact force acting on the pier and the pier's response. Therefore, the observations from hard impact tests may not reliably reflect the performance of piers under soft impacts. In this study, the influence of impact type on the impact response of segmental bridge piers was experimentally investigated using soft and hard missiles of identical mass. The results showed that the change in impact type led to different dynamic responses and damage distributions in segmental piers. Specifically, obvious bottom slippage occurred during a soft impact, followed by the rocking response of the segmental pier without significant structural damage, while repeated soft impacts caused severe damage to the bottom segment due to the damage accumulation. On the other hand, a hard impact led to the relative slippage between impacted segments, accompanied by extensive concrete spalling damage and shear failure of bottom segment due to the effect of intense stress waves. Furthermore, soft and hard impacts also affected the changes in prestress forces on both sides because of the differences in deformation characteristics, response mechanisms and degree of damage of segmental piers under different impact scenarios. A numerical model was also developed in LS-DYNA to simulate truck collisions on segmental bridge piers. The reliability of numerical model was verified against the experimental test results. A parametric analysis considering various truck collision scenarios was then performed using the verified numerical model to investigate the effect of different truck parameters on the impact response of segmental bridge piers combined with the characteristics of soft and hard impacts.