A Numerical Investigation of the Performance of Damaged Concrete Barriers Under Sequential Vehicular Impacts

Concrete median barriers are prone to damage from low-velocity impacts. However, there is a limited understanding of how damage from initial impacts affects barriers’ long-term performance and whether they maintain safe continued service or must be replaced. Therefore, this paper evaluates the performance of the concrete barriers under sequential low-velocity impact using finite-element analysis. Crash test simulations were performed by impacting the concrete barrier twice with an 80,000 lb (36-ton) tractor-trailer at a target impact velocity and angle. The first impact’s velocities varied between 30 mph (48 kmph) and 54 mph (87 kmph) at 10°, 15°, and 20° crash angles, and the damaged barrier was subsequently subjected to the second impact conforming to the American Association of State Highway and Transportation Officials’ (AASHTO) Manual for Assessing Safety Hardware (MASH) for Test Level 5 criteria (i.e., representative velocity of 52.7 mph (85 kmph) at 15°). Therefore, a total of 78 impact simulations were conducted, and statistical analysis was performed to investigate the relationship between the peak impact forces of the first and second impacts and the crash angle and velocity across distinct phases of the crash simulation and over the entire crash history. The results show that while the peak impact force of the first impact was linearly related to both velocity and angle, the maximum impact force at the second impact did not follow the same trend. However, when considering the localized peak forces in each phase of the crash, the peak forces from the later stages of the second impact (i.e., rebound and final interaction phases) were highly correlated with the initial impact’s velocity and angle, substantially reducing the barrier’s capability to resist vehicular impact loads. In particular, for initial velocities above 46 mph (74 kmph) at angles of 15° and 20°, barriers formed shear cracks traversing across their cross-section, which resulted in excessive fragmentation during the second impact and consequent failure to meet the MASH criteria in terms of structural adequacy.