Development of a three-dimensional simulation model of vehicle-bridge railing crash - A computer-aided approach to bridge railing stiffness design

To improve the conventional lengthy and inefficient design process for bridge railings, which features repetitions of costly full-scale experiments, and to support the bridge railing design with analytical data, this research developed a three-dimensional (3-D) simulation model that can reconstruct a vehicle-bridge railing impact analytically and visually using MADYMO (MAthematical DYnamic MOdel), developed by TNO. Both the vehicle and the bridge railing are modeled as rigid multibody systems. A nonlinear tire model and a 3-D suspension are introduced to increase the reality of the vehicle motion during impact. The bridge railing is divided into poles and longitudinal railings. The bending characteristics of the poles and the longitudinal railings are described by the properties of corresponding universal joints attached to them. The simulation model is verified by experimental data of three different conditions using heavy trucks (8 tons and 20 tons). The validation reveals that the 3-D model can reconstruct vehicle-bridge railing crashes with a high degree of accuracy with respect to the vehicle performance and the deformation of the bridge railing, which are the most important concerns in the designs of bridge railings. The validated crash model is then employed to determine the necessary stiffness of the bridge railing under different conditions. Curves describing the relationship between the stiffness of the poles and the longitudinal railings are calculated for various impact severity values. These curves provide analytical grounds for the stiffness designs of the bridge railings.