Experimental and numerical investigations on methods for improving impact performance of precast segmental bridge piers

Precast segmental bridge piers (PSBPs) are increasingly used in accelerated bridge construction. However, segmental joints and bottom segments are more vulnerable to severe damage under impact loads. This study experimentally and numerically investigates three retrofitting methods to improve the impact performance of PSBPs, i.e., wrapping carbon fiber reinforced polymer (CFRP) sheets around segment joints, using steel tubes to connect the bottom two segments, and adopting a cast-in-place bottom segment. The effectiveness of these methods was first verified through missile impact tests. Results indicated that wrapping CFRP sheets around joints effectively reduced concrete spalling damage within the impacted zone but led to more severe bottom shear damage due to improved integrity and joint restraint. In contrast, the use of continuous steel tubes extending through the joint to connect the two bottom segments and the cast-in-place longer bottom segment could enhance the impact performance of PSBPs by effectively activating their energy-dissipation mechanism. Numerical models of the four types of PSBPs subjected to missile impacts were then established and validated against test results using the explicit dynamic analysis software LS-DYNA. An analysis of the PSBPs subjected to off-center missile impacts was then performed. Results confirmed the effectiveness of using steel tubes to join the two bottom segments and the cast-in-place of a longer bottom segment to improve the performance of PSBPs subjected to off-center impacts, while wrapping CFRP sheets around joints weakened the impact performance of PSBPs in off-center impact scenarios. These findings provide experimental and numerical evidence to support the selection of suitable retrofitting strategies to improve the impact performance of PSBPs in complex collision scenarios.