Development of an overlaid concrete median barrier: Numerical studies and full-scale field tests

This study aims to develop an overlaid CMB(Concrete Median Barrier) with a containment level of SB5 (230 kJ of impact severity) based on a series of numerical simulations and full-scale field tests. The 810-mm CMB (CMB810) currently in service on roads, should be overlaid up to height of 1370 mm (CMB1370) with containment level of SB5 to prevent vehicles from traveling over it. From a series of numerical simulation, the effects of dowel/longitudinal bars on structural adequacy and occupant risk were quantitatively assessed in order to develop the CMB1370. Numerical analyses indicate that decreasing the spacing of dowel bars and the proximity of longitudinal bars from the top of the CMB1370 can significantly lessen the volume loss incurred during vehicle-to-barrier collisions. The numerically proposed CMB1370 underwent full-scale field tests in compliance with three evaluation criteria: (1) structural adequacy, (2) occupant risk, (3) vehicle's post-impact trajectory. The full-scale field test results demonstrated that the CMB1370 effectively contained and redirected the vehicle without any instance of damages, penetration or overriding. The measured deformation of CMB1370 by several LVDTs was within acceptable limits for use on the road. Previous full-scale field tests, the primary focus was on the structural adequacy of the CMB and the resulting damage it sustained. However, these findings provide new insights into the behavior and rehabilitation of the CMB, as well as the damage sustained at impact. Moreover, no significantly fragmented debris larger than 2.0 kg was observed from the barrier. Thus, the proposed CMB1370 meets all the requirements specified in the crash test guidelines in Korea.