Performance of curved steel bridge railings subjected to truck collisions

Curved steel railings are used along curved road sections and bridges for safety. As with other railings, they are required to meet four performance standards as: (1) to prevent vehicles from leaving the road; (2) to protect occupants; (3) to guide vehicles back to the line of the road; and (4) to prevent penetration of the railing. Current Japanese specifications for railing design concern only straight railings. Some researchers and engineers suspect that curved railings are more dangerous than straight ones and this study finds that the impact angle between truck and railing, which affects both railing and truck behavior, can be larger than the angle allowed for in the Japanese specifications in some actual cases of curved roads and bridges. The purpose of this research is therefore to verify the above suspicion and to investigate the performances of curved railings subjected to collisions at the larger impact angles. A full-scale test would be the ideal methodology for this purpose but a test of the right sort would involve a considerable cost and effort. Thus numerical analyses are relied on to study the performance of curved steel railings according to the following procedures: (1) the railing and truck are represented by finite element models; (2) various cases are simulated of truck collisions with railings; and (3) numerical results are obtained for the consequent displacements, energy responses and truck behaviors as a means of evaluating the railing performances. The railings investigated in the various simulation cases are of grade SC and are either straight or have a curve radius of 100 m, 150 m, 280 m or 460 m. The software engine used for the numerical analysis is LS-DYNA 3D. Based on the results of the study, a design recommendation is proposed for curved railings.