Design and Finite Element Analysis of a MASH 31-inch W-Beam Guardrail System for Placement on 3H:1V Sloped Terrain Configuration (2014 WV-62)
Author(s):
C. Silvestri Dobrovolny, D.R. Arrington, N.D. Schulz, C.B. Xavier
Publication Date:
September 2015
Abstract:
In locations where a traversable slope is located at the edge of the shoulder, there may be a desire to offset the barrier to minimize impacts. A longitudinal system that can be placed on 3H:1V slopes would provide this flexibility. The purpose of this research was to develop a 31-inch W-beam guardrail system to be placed with a 3H:1V slope in front of the barrier. The structural capacity and the occupant risk factors of such proposed guardrail system was evaluated with respect to MASH TL-3 criteria. The information compiled from this research will provide the Federal Highway Administration and State Departments of Transportation with a W-beam guardrail design as a crashworthy system to be placed with a 3H:1V slope in front of a barrier. Being able to place W-beam guardrail with a 3H:1V slope in front of the barrier would reduce the number of impacts on the system and would provide flexibility in the placement of W-beam systems. Impact simulation of MASH test 3-11 according to the initial impact conditions of test 405160-20-1 well replicated the results obtained through full-scale crash testing. Failure properties were applied to the connection between the wheel and the vehicle to allow joint connections to fail once reached a predefined force value. The FE models of the test article and the vehicle were used as a base model to develop new guardrail designs for evaluation when placed on a 3H:1V sloped terrain configuration.
Three barrier designs for placement on a 3H:1V slope were suggested for evaluation through predictive computer simulations:
1. Design 1: 31-inch W-beam rail, 7-ft steel post, wood blockouts; 3H:1V slope with posts placed 1 ft from the slope break (face of the guardrail aligned with the slope break); No rubrail (MASH test 3-11);
2. Design 2: 31-inch W-beam rail, 8-ft steel post, wood blockouts; 3H:1V slope with posts placed 2 ft from the slope break; No rubrail (MASH test 3-11);
3. Design 3: 31-inch W-beam rail, 8-ft steel post, wood blockouts; 3H:1V slope with posts placed 2 ft from the slope break; with rubrail (MASH tests 3-10 and 3-11).
All systems appear to be crashworthy and likely to pass safety evaluation criteria required for MASH. Depending on the desired system post distance location from the 3H:1V slope break, the researchers recommend evaluation of selected design through full-scale crash testing according to MASH TL-3 criteria.
Report Number:
12-602951-00001
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