Coupled Vibration Between Vehicles And Highway Long-Span Continuous Series Bridge

Long-span continuous series bridge which includes the continuous girder bridge,continuous rigid frame bridge and continuous girder-frame bridge has been studied in thispaper. Due to the ability of long span, well established construction technique andcost-effective, long-span continuous series bridge has being widely adopted in civilengineering practice. However, as the span distance increases, the full structure tends to beslim and unstable thus the coupled vibration between vehicles and highway long span bridgebecomes more pronounced. The coupled vibrations were of great interests for both academicsand engineers recently and the study of these coupled vibrations has much significantmeaning not only to the engineering practice but also in the research levels.Currently, the study of the coupled vibrations in the complex structure bridge and theanalytical work of the influencing factors are premature in engineering practice. However,under the help of the advancing computer technique, some numerical methods could beeffectively used in modeling those complex structures. Among those numerical methods, onefinite element method (FEM)-ANSYS could be easily used to model any coupled vibrationsin complex structure bridge under hybrid traffic loadings. This research is part of the project<Coupled Vibration between Vehicles and Highway Long-Span Continuous Series Bridge>(200831881232). The results of this are presented below:(1) A numerical solution was established which was found very practical to analyze thecoupled vibrations between Vehicles and Highway Long-Span Continuous Series Bridge. TheFEM software ANSYS was utilized to model the vehicles and bridges. Based on the boundarycondition from the special properties of modeled vehicles and the relative distance betweenvehicles and bridge, the force between vehicles and bridge could be easily calculated at anytime during complex traffic loadings. APDL program could effectively assists modeling andadding analytical nods to the vehicle bridge element thus the coupled vibrations could benumerically solved by ANSYS software only. By comparing with the literature andexperimental data, this method could be applied to constant speed vehicles, constantaccelerating speed vehicle loadings and uneven surface roughness bridge conditions.(2) An analytical coupled vibration system was developed based on the numericalsolution from ANSYS. In this system, only the vehicle and bulk construction coefficients areneeded in order to carry out the coupled vibration analysis. Once these two coefficients aredetermined, the system will call and run ANSYS and produce results in EXCEL file when theanalysis is complete. This system also incorporates the influence from vehicle properties (the number of axles, spring properties, and weight), the speed of vehicles, and the surfaceroughness of the bridge. The developed analytical system has been patented by Chinasoftware bureau.(3) Besides the analytical system mentioned above, other analytical softwares have beendeveloped so that to solve some evaluation problems from the uneven surface roughnessbridge, the transformation between MIDAS model and ANSYS model, the impact analysis inthe time distance domain and the degree of comfortable of drivers during driving. Thosesoftwares also patented and commercialized to help engineers in practice.(4) By using the developed analytical system, the coupled vibration influencing factorssuch as the weight of the vehicle, the frequency, the number of traffics, the surface roughnessof the bridge, the speed of the vehicle, and the acceleration speed were extensively studied.The moment impact coefficients of the major span, peek vertical acc and their variation werealso studied which have great significance in studying the coupled vibrations.(5)4Long-Span Continuous Series Bridge were adopted as prototype and32bridgeswhose span between80-200m and pier height between0-100m were modeled. The sensitivityof the moment impact coefficients of the major span, peek vertical acc and their variationwere analyzed and how the spans, pier height, surface roughness, vehicle speed, the verticalvibration frequency and traffic time difference influence the coupled vibrations were studiedand summarized.(6) Coupled vibration analysis was carried out for14different existing bridges underdifferent surface roughness and different traffic conditions. The moment impact coefficientsof the major span, pier and peek vertical acc empirical calculation equations were achievedfrom regression analysis. In the regression, the major surface roughness coefficients wereincluded which enriched the current standard because the standard cannot account for themajor surface roughness effects. Finally, a solution to calculate the displacement of the pierand moment under both mono traffic loading and complex traffic loading conditions weredeveloped which could be effectively used to evaluate the occurrence of resonance betweenvehicles and bridges.