Coupled Vibration Analysis of Train-Bridge System Considering Soil-Structure Interaction
|Keywords||train-bridge system coupled vibration soil-structure interaction (SSI) seismic excitation dynamic analysis continuous rigid-framed bridge soft foundation|
The coupled vibration of train-bridge system is aggravated due to the speedingof trains and the construction of light railways, and is further intensified due to thefoundation deformation on soft soil, which will undoubtedly reduce the degree ofsafety of the train running. In order to ensure the safety of the train running on thehigh-speed railway or the light railway, it is urgent to analyze the coupled vibration ofthe train-bridge system and consider the influence of the foundation deformation onthe coupled vibration. In this thesis, the coupled vibration analysis of the train-bridge system issystemically performed considering the soil-structure interaction (SSI). Based onreviewing the current progress on the coupled vibration of the train-bridge system andthe analysis of SSI, a method for the coupled vibration analysis of the train-bridgesystem considering the SSI effect is proposed, in which all factors to induce thecoupled vibration and its importance are systemically investigated and then theprimary factors are properly augmented by ignoring the secondary factors, and theStep-by-Step Integral method is adopted to solve the quadratic differential equationswith the time-varying coefficients. Taking a four-span continuous rigid-framedprestressed concrete bridge in Tianjin light railway engineering as an example, thethree-dimensional spatial model for the coupled vibration analysis of the train-bridgesystem considering the effect of SSI is established, in which a model of train with 27degrees of freedom, the spatial beam element model for the girder and piers, aequivalent single-pile model for the grouped-piles foundation and a spring-dampermodel for the soil surrounding the piles are included. The related computer programis generated, the influence of the effect of SSI on the coupled vibration of thetrain-bridge system is numerically analyzed, and the influence of the seismicexcitation on the coupled vibration of the train-bridge system considering SSI isfurther investigated. Finally, some conclusions are given as follows. (1) The dynamiccharacteristics of the bridge on the soft soil is significantly affected by consideringthe SSI effect, in which its natural frequencies are much lower than those of thebridge with end-fixed piers, so that the SSI effect must be taken into account in thecoupled vibration analysis of the train-bridge system. (2) By considering the SSIeffect in the coupled vibration of the train-bridge system, the lateral displacement<WP=5>responses of the bridge are most intensively affected, and the rotational displacementresponses of the bridge are much intensively affected, but the longitudinal andvertical displacement responses are much slightly affected. (3) The lateral wobblingforce of the train is the foremost cause to induce the lateral vibration of thetrain-bridge system, whereas, the moving gravity force of the train is of limit effect.(4) There is a rather large degree of coupling between the vibrations of the bridgeinduced by the seismic action and the train passing the bridge, which cannot besimply superposed by the seismic responses and the responses of the coupledvibration.