| China’s w-beam semi-rigid guardrail draws lessons from foreign mature guardrail structure form and there is a lack of its own theoretical design method. With the support of open project funds, W-beam guardrail design calculation method under impact load was researched in order to provide reference for Key Laboratory of Road Safety Technology to develop new guardrail structure.By analyzing vehicle and guardrail collision process and considering the effect of strain rate, the calculation model of impact force design value was put forward. The guardrail failure mode was determined according to the result of real vehicle full-scale field test and the finite element simulation analysis. The ultimate strength of the structure was calculated by energy balance principle, and then theoretical design method of w-beam guardrail was established. Comparing the new method with the other two existing design methods, the results showed that the design method of American code was too conservative and Shi-Hongxing’s method was kind of risky. Only the evaluation index of new method matched well with the finite element simulation results, which proved the soundness of the new design calculation method.As the new design method couldn’t reflect the relevant index of vehicle operating attitude, additional design using the finite element simulation analysis was required. Based on the simulation analysis of w-beam guardrail structure, the crashworthiness influence rule about how different w-beam and the column stiffness will impact on the vehicle operating attitude was obtained. The influence rule could be used for preliminary screening of unqualified guardrail structure.W-beam guardrail design under grade A collision condition has been completed utilizing the new design system and three kinds of qualified guardrail structure were selected. These three structures could provide reference for real vehicle full-scale field tests and development of grade A w-beam guardrail. |
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