MODIFIED CALCULATION METHOD FOR MAXIMUM IMPACT FORCE BETWEEN TRUCK AND ANTI-RAM BOLLARD BASED ON CAMPBELL'S MODEL

In order to study the maximum impact forces of anti-ram bollards subjected to truck crash, sixty-three numerical experiments were conducted to simulate the crash processes. The crash features of the trucks after impact were presented and analyzed. Then, Campbell's model was modified using the truck equivalent crush. Based on the modifications, a new calculation method for the maximum impact force between truck and bollard was proposed. In addition, the applicability of the calculation methods in the domestic and international related specifications was evaluated. The results show that the distribution of the truck crash deformations after impact is not uniform in width, and the crush at the center is larger than that at the ends. Truck equivalent crush is not only influenced by the truck impact speed, but also related to the bollard height and diameter, the yield strength and thickness of steel tube, and the foundation depth. The comparisons between calculated results and experimental results from truck crash tests and numerical simulations indicate that the predictions by the Annex B of Eurocode 1 are much less, the predictions by the Annex C of Eurocode 1 and Chinese code JTG D81-2006 are dispersive, and the predictions by the proposed method are more accurate and conservative. Therefore, the modified calculation method based on Campbell's model can be applied to the design of anti-ram bollards.