Numerical analyses on impact performance of steel and aluminum alloy bridge guard fences

A new code for the design of the guard fence performances was implemented and issued in April 1999 in Japan. The prescribed performances of the new code are: i) prevention of derail, ii) safety of occupant, iii) leading vehicles to road, and iv) prevention of spreading out the broken pieces. In the new code, the full-scale experiment for checking the performances of guard fences is required in the determination of the structure of the guard fence. However, it is very difficult to test the performance of full-scale guard fences in the field for the parametric examination because of the huge time and cost consumption. In this study, the numerical analysis using LS-DYNA under the simulated condition of the truck-to-fence crash has been carried out for the steel and aluminum bridge fences. The results of analyses are compared with the results of field experiments. The tensile experiment is conducted to determine the stress-strain relationship and the strain rate of materials. According to the calculation results, it was found that the strain rate has to be considered for the analysis and design of steel guard fences, but does not effect the results the aluminum guard fences.