Crash modeling of bridge railings: Impact of post spacing on performance

The object of research is a barrier side one-way bridge railing with a height of 1.1 meters and a rack spacing of 2 meters. The purpose of this work is to analyze the effectiveness of the finite element method (FEM) in modeling the collision between a bus and the bridge railing, and to determine the impact of rack spacing on the railing's performance characteristics, such as dynamic deflection and working width. Method. The FEM is employed to simulate the collision dynamics between the bus and the bridge railing. The railing model consists of several key components: bridge post, upper rail, console-absorber, and lower beam section, all modeled using 2D shell elements. The bus model includes detailed geometric and material properties, validated through simulations to ensure accurate replication of real-world conditions. Simulation parameters – such as initial speed, angle of impact, and the material properties of the bus and railing components – are based on experimental data. The quality of the model is assessed using criteria including trajectory deviation, suspension displacement, and acceleration at the vehicle's center of mass. Results. The comparison of simulation results with full-scale tests confirms the validity of the FEM model. Key findings include the stability of the bus trajectory without overturning or railing overrun, and the effective containment capacity of the railing, capable of withstanding a kinetic energy impact of 406.34 kJ. The study identifies the optimal rack spacing for balancing metal consumption and dynamic deflection, which ranges between 1.5 meters and 2 meters. The results indicate a significant correlation between rack spacing and the railing's performance characteristics, with detailed comparisons of dynamic deflection and working width for various spacings. The calculated dynamic deflection and residual deformation values closely match experimental results, affirming the reliability of the FEM approach in modeling these complex interactions.