Simulation study on the reinforcement method for roadside barriers with partially reduced load-bearing capacity

This study examines the safety performance of roadside barriers installed on highway culvert sections where achieving the standard embedment depth (1.3 m for SB3-grade barriers) is challenging. A field survey of 18 culvert locations revealed that six sites had an average embedment depth of 0.83 m, which is 0.47 m shallower than the required standard, potentially compromising structural integrity and occupant protection. To assess crashworthiness under these conditions, numerical simulations using LS-DYNA were conducted and validated against full-scale crash test data. Simulations of SB3 barriers with a reduced embedment depth of 0.6 m revealed excessive lateral deformation after failure and vehicle wheel snagging, contributing to further structural instability. Barrier failure persisted even at an embedment depth of 1.0 m, suggesting that increased depth alone may not ensure structural adequacy. To mitigate these risks, reinforcement strategies were explored. The most effective solution (CASE 4) involved adding reinforcement beams at the lower section of posts, extending across multiple standard-depth posts before and after the low embedment region. This configuration successfully distributed impact forces, prevented excessive deformation, and maintained structural integrity while meeting occupant protection and post-impact safety criteria. These findings suggest that reinforcement is a viable alternative to increasing embedment depth in constrained environments. Future research should validate these results through full-scale crash testing and explore their applicability to higher-grade barriers such as SB5. This study offers insights into enhancing highway safety where structural constraints limit the installation of standard guardrails.