Effects of Different Beam Elements on Dynamic Responses of Coupled Train-bridge System

Research purposes: Based on train-track-bridge coupling dynamics, the effects of three types of simply supported beams modeled as a Euler-Bernoulli beam, Timoshenko beam and shell-element system, respectively, on the dynamic responses of the coupled train-track-bridge system are studied. Then, taking a six-span simply supported bridge passed through by a high-speed train composed of 12 cars for the case study, the comparisons of dynamic responses of three types of coupled train-track-bridge system are undertaken. Research conclusions:(1) The natural frequencies of the three types of simply supported beam models with the same section and material parameters are different. The Euler-Bernoulli beam has the highest natural frequency, as well as the resonant speed. (2) At the operating speed, the acceleration response of the simply supported beam is affected significantly by the type of element, and the Euler-Bernoulli beam has the smallest bridge acceleration. The vibration acceleration of the Timoshenko beam is close to the calculation result at the midpoint of the bottom plate of the box girder of the shell-element system. The top deck of the box girder of the shell-element system, which subjects to the local high-frequency excitation, has the highest acceleration. The acceleration of the first and last vehicle body of the three types of models coincides well. (3) At the resonant speed, the acceleration and displacement of bridge obtained by the Euler-Bernoulli beam and the Timoshenko beam are in excellent agreement, but on the whole, they are larger than that of the shell-element system. The Euler-Bernoulli beam model is quite different from the Timoshenko beam model at the acceleration of the last vehicle body. The dynamic response of the last car is considerably larger than that of the first car due to the passage of the serial beams in resonance. (4) The research results can provide reference for the selection of bridge numerical model in the study of train-track-bridge coupling vibration. © 2020, Editorial Department of Journal of Railway Engineering Society. All right reserved.