Study On Influencing Factors And Preventive Measures For Vertical Resonance Of High Speed Train-Bridge System

With the more and more high-speed railways operated, the resonance problem of vehicle and bridge has been got more attention than before. The previous scholars gave more attention to the bridge’s resonance than vehicles’when they researched the train-bridge system resonance. In this paper, the vehicle and bridge resonance problem is discussed deeply by using the models and equations of vertical motion for train-bridge system. Then, the rationality of bridges’natural frequencies’ limit value is discussed, which is given by the Chinese high-speed railway design specifications. The main research contents and achievements have been obtained as follows.1. In order to analyze the resonance conditions and preventive measures of vehicle resonance, a ten degree model of vertical motion for vehicle has been established. Based on this model, the first order natural frequencies of CRH3are calculated as0.6312Hz and0.567Hz respectively.2. Based on the assumption of wheel-rail contact, the models and equations of train-bridge system are formulated by means of the principle of total potential energy with stationary value in elastic system dynamics and "set-in-right-position" rule for formulating matrices. Then the program for calculation is compiled with FORTRAN language, and the program is also verified.3. The influencing factors of train-bridge system vertical resonance are discussed and the consequences as follows:ⅰ) The speed of vehicle and the natural frequency of bridge are the two uppermost factors for bridge’s resonance and the influence of bridge vibration by track irregularities is very small; ⅱ) Increasing the bridge’s damping cannot avoid its resonance. The response can be weaken when the bridge is in resonance; ⅲ) The dynamic distributed train formation and the dynamic centralized one have the same effect on avoiding the bridge’s resonance; iv) The equal and continuous of bridge span’s arrangement is the main factor of vehicle’s resonance, when the influence of track irregularity is not taken into account; ⅴ) The phenomenon of vehicle’s resonance is not obvious, and the vibration response increases a lot when the influence of track irregularity is considered. So when the dynamic response of train-bridge system is analyzed, the influence of track irregularity needs to be considered.4. Based on the principle that a rapid in crease does not appear in the curve of bridge dynamic factor-train speed within the design speed range, the limit values of the bridge’s natural frequency are presented to prevent the bridge’s resonance. When the design speed are350km/h,300km/h and250km/h, this number are determined as150/L,130/L and110/L respectively. In addition, the lower limit value of the bridge’s natural frequency is demonstrated to be of no significance, and it is also testified that the higher limit value of the bridge’s natural frequency is not needed to be given in the design specification.