Date of this Version
Rosenbaugh. S.K., Hartwell, J.H., Bielenberg, R.W., Faller, R.K., Holloway, J.C., and Lechtenberg, K.A. (2017). "Evaluation of Floorpan Tearing and Cable Splices for Cable Barrier Systems" Nebraska Department of Transportation Research Report TRP-03-324-17.
This research effort consisted of two objectives related to components of a prototype cable barrier system. The first objective was to mitigate the potential for vehicle floorpan tearing by modifying the cable guardrail posts. A bogie vehicle was equipped with a simulated floorpan designed to replicate the height, thickness, and strength of the floorpan of a Kia Rio vehicle. Baseline testing demonstrated that the top of the Midwest Weak Post (MWP) would contact, and crease the simulated floorpan, which matched the damage observed in actual full-scale vehicle crash tests. Once the test setup provided the desired results, various post configurations were tested including S3x5.7 (S76x8.4) posts, MWPs with edge rounding, MWPs with steel plate edge protectors, and MWPs with weakening holes/slots. Three different weakening patterns were evaluated: ¾-in. (19-mm) diameter hole; three ⅜-in. (10-mm) diameter holes; and ⅜-in. x 1⅛-in. (10-mm x 29-mm) slots. All three weakening patterns showed the ability to reduce the propensity for floorpan tearing. However, additional bogie testing of the posts resulted in significant reductions in strong-axis strength for the latter two weakening patterns. The ¾-in. (19-mm) diameter hole resulted in a 10 percent reduction in strong-axis bending strength, and thus, was recommended for further evaluation through full-scale vehicle crash testing.
The second objective was to investigate the structural capacity of other cable splice hardware that would reduce the propensity for vehicle snag and sheet metal tearing. A review of existing hardware was conducted to identify possible couplers. Next, three component tests were conducted to evaluate two models of Bennett Bolt Works mechanical couplers. Test results for the new coupler, model no. CGBBWTH, showed promise, however the targeted failure strength of 39 kips (174 kN) was not satisfied for either the new coupler, model no. CGBBWTH, or current coupler, model no. CGBBHT. There is potential that the couplers used in test no. BBNC-3 sustained damage in previous testing which would make them susceptible to premature failure, therefore further testing and evaluation of both coupler models will be necessary to gain a better understanding of their strengths and durability.