Wood-steel structure for vehicle restraint systems

Certain roadside safety barriers are structures made of steel and wood. This kind of structure is currently in fashion in location where the safety equipments need to be discreet (mountains, countryside). In Europe, to be installed on the roadside, the vehicle restraint systems have to pass two crash tests, as defined in the European standard EN1317. Our aim is to develop a dynamic model of the multi material structure in order to understand and optimize the safety barriers i.e. to define the best association of the mechanical properties of both materials. The first part of this paper concerns three point bending experimental tests at different energy levels. These laboratory tests were used as a basis for the evaluation of a material constitutive law. Then, a numerical parametric study which takes into account the variation of moisture content and temperature, as observed in the experiment, will be exposed. After that, a model of a roadside safety barrier and a procedure based on variation of failure modes analysis will be presented in order to correlate the numerical model to the real crash test results. Finally, a parametric study, concerning wood mechanical properties, will be performed in order to check the effect of this variation on the device performances.