Numerical Studies on Concrete Barriers Subject to MASH Truck Impact

In January 2016, the FHWA and AASHTO announced a joint agreement that only bridge railing and longitudinal barriers evaluated using the 2016 edition of Manual for Assessing Safety Hardware (MASH) will be allowed for new permanent installations after December 31, 2019. However, in the current AASHTO-LRFD, railing design forces and their applications for concrete barriers have not been updated to MASH requirements, and the detailed impact process of the MASH truck on concrete barriers has not been systematically investigated. In most of the previous studies on MASH truck impacts, the concrete barrier had been assumed to be arigid structurecapable of sustaining a vehicular impact without any significant damage. This assumption neglects the deformation of the barrier and does not improve our understanding on the barrier's failure mechanisms. In this study, high-fidelity finite-element simulations have been carried out to investigate the demands imposed upon, and damage modes of, MASH TL-4 and TL-5 concrete barriers. An inelastic pushover analysis approach is proposed for the evaluation of the capacity of these concrete barriers. Based on the damage mode observed from the pushover analysis, a modified yielding line method (MYLM) is proposed for estimating the capacity of concrete barriers. It is observed that the capacity of concrete barriers estimated by the proposed MYLM matches with that from the pushover analysis quite well and it is generally much higher than from the current AASHTO-LRFD specifications.