Crash Impact Analysis of the G2 Guardrail: a Validation Study

Prototype guardrails, bridge rails, crash cushions and other roadside safety hardware have been designed in part by using engineering judgment, experience and intuition. These prototypes have been later evaluated by performing full-scale crash tests representing expected worst case scenarios. Since these tests are relatively expensive and because they require specialized facilities and personnel, the result is that important decisions are quite often based on the results of a few full-scale crash tests. Many highly effective roadside safety hardware systems have been developed using this process, but difficult issues remain. Due to the increased complexity of today’s vehicular fleet and the fact that full-scale crash tests do not provide sufficient information about loads, accelerations, stresses and strains to develop designs based on the mechanical behavior of barrier components, analytical methods have become a necessity. This paper reflects the nationwide research trend to utilize analytical methods for improvement of highway roadside safety hardware. A finite element model of the G2 weak-post w-beam guardrail was impacted by a finite element model of a 1994 Chevrolet pickup truck traveling at 100 km/hr and impacting the barrier at 25 degrees. LS-DYNA3D, a nonlinear, explicit dynamic finite element code, was used to perform the analysis. Results are discussed and compared to data from a full-scale crash test. Acceleration time histories are compared using time domain analysis. The average residual, standard deviation of the residuals and the t-statistic for the simulation and test curves are also reported.