Over-height truck collisions with railway bridges:attenuation of damage using crash beams

Railway bridges are susceptible to over-height truck collisions and to address this issue,it is necessary to attenuate the effect of these impacts to ensure the safety of transportation operations.This study experimentally investigates the effectiveness of crash beams as a cushioning mechanism for railway bridges against collisions.Over-height truck and railway bridge impact events were simulated in a 1:5 scale experiment.The design parameters such as the stiffness of the crash beam and the bridge supports were scaled to evaluate different levels of attenuation.Seventeen experiments were conducted with five configurations consisting of four different types of crash beams and one no-crash beam arrangement.The results show that crash beams attenuate bridge total peak dynamic displacement responses between 14.5%and 35.7%,depending on the intensity of the impact and crash beam type.In addition,the results show that the average effectiveness in attenuating residual deformation for all four crash beams ranges from 43.03%to 83.40%.Finally,various designs and their effectiveness against lateral impacts with different speeds are discussed.The overall scope of this research is to provide objective information about the design of crash beams for railway bridges based on their response to over-height truck collisions at various speeds.

Longitudinal forces of continuously welded track on high-speed railway cable-stayed bridge considering impact of adjacent bridges

A proven beam-track contact model was used to analyze the track-structure interaction of CWR (continuously welded track) on bridge. Considering the impact of adjacent bridges, the tower-cable-track-beam-pier-pile finite element model of the cable-stayed bridge was established. Taking a bridge group including 40-32m simply-supported beam and (32+80+112)m single-tower cable-stayed bridge and 17-32m simply-supported beam on the Kunming-Shanghai high-speed railway as an example, the characteristics of CWR longitudinal force on the cable-stayed bridge were studied. It is shown that adjacent bridges must be considered in the calculation of the track expansion force and bending force on cable-stayed bridge. When the span amount of adjacent bridges is too numerous, it can be simplified as six spans; the fixed bearing of adjacent simply-supported beams should be placed on the side near the cable-stayed bridge; the track expansion device should be set at the bridge tower to reduce the track force near the bridge abutment.

Analytical solution to mapping rail deformation under bridge transverse deformation using energy variational principle

The track geometry is a critical factor that affects the running safety and riding comfort of trains moving on a high-speed railway bridge.This study addresses the mapping relationship between the track deformation and lateral deformations of bridges.Equilibrium equations and natural boundary conditions of the track-bridge system are established based on the energy variational principle,and an analytical solution is derived for the track deformation accounting for lateral bridge deformations.A five-span simply-supported bridge with continuous welded rail has been selected as the case study.The mapping rail deformations are compared to the finite element results,and both results agree well with each other,validating the analytical method proposed in this paper.The influence factors on the mapping rail deformation are further evaluated.Results show that the mapping rail deformation is consistent with the girder displacement at the area that is away from the girder ends when the flexural stiffness ratio between the track and the bridge girder is low.The interlayer stiffness has a significant effect on the mapping rail deformation when the track flexural stiffness is of a high value.