Numerical investigation of K4-rating shallow footing fixed anti-ram bollard system subjected to vehicle impact

Abstract

Preventing unauthorized vehicles from approaching a protected area by anti-ram bollard systems installed in the perimeter of buildings and infrastructures would consequently reduce blast and debris threats of vehicle borne improvised explosive devices. In this paper, an explicit finite-element model, which is more comprehensive than existing numerical models, was developed to simulate the performance of fixed anti-ram bollard system subjected to vehicle impact. Different materials for different locations of the foundation support, differences in weight and configuration between test vehicles and vehicle model, and more accurate contact algorithm used between truck and bollards were taken into account. The accuracy of the developed model was validated through comparing the impact results with four existing crash tests. Based on the verified numerical model, 72 numerical experiments of K4-rating shallow footing fixed anti-ram bollard systems (SFFABSs) were investigated according to orthogonal design. The minimum height of the bollard Hmin during the impact was proposed as a new deformation tolerance for K4-rating SFFABS. The new deformation tolerance is defined as the Hmin value of 564mm or above according to SD-STD-02.01 Revision A, and a more reliable deformation tolerance is defined as the Hmin value of 587mm or above. Orthogonal analysis for the experimental factors with respect to Hmin showed that height of the bollard, diameter of the bollard, and strength of the steel tube have greatly significant influences on Hmin.