Assessment of structural adequacy of semi-rigid safety barriers

A procedure for assessing the structural adequacy of semi-rigid barriers, consisting of the determination of load-carrying capacity using plastic analysis and the calculation of the impact load, is presented. To reflect the dynamic effects of the soil, the plastic moment of posts is defined by multiplying the dynamic resisting force of a post by the distance from the impact loading point to the position of a plastic hinge. The impact load was determined by using a modified Olson model, idealizing the vehicle lateral acceleration-time relationship as a triangle instead of the half-sine function of the Olson model. For semi-rigid vehicle barriers with relatively small lateral stiffness, the proposed structural adequacy assessment procedure and FEA provided approximately the same results. However, for semi-rigid vehicle barriers with large lateral stiffness, the assessment procedure using the first impact load, different from the assumption of the modified Olson model, produced a rational design.