Research On Resonance Response In Train-bridge Coupled System Based On Pseudo Excitation Method

High proportion of bridge is a significant measure which guarantees the stability of high-speed trains.However,the increasing train speed tendency has greater effect on bridge vibration doing harm to the safe operation of high-speed trains.Particularly,the resonance of bridge occurs when loading frequency is equal to its natural frequency.Meanwhile,the track irregularity random vibration typically randomizes the resonant response of bridge,on which the research with a single spatial sample is uncertain while the oversampling is precise but inefficient.Hence,adopting pseudo excitation method(PEM)for the efficient analysis of train-bridge resonant response is of great significance to the safety and stability of train-bridge system.The research in this thesis mainly covers:1 Relevant methods and theories of random vibration are built and mainly includes random process theory and PEM.The stationary and non-stationary random excitation is modeled as a simple harmonic pseudo excitation respectively solved by complex frequency-response function and precise integral method(PIM),which helps to calculate the power density spectrum and the standard deviation of system response.The vibration equation of train-bridge interactive system is formulated and the nodal shape function decomposition time history function of load is derived.Inter-history solution process based on PEM-PIM is analyzed,which verifies the accuracy and efficiency of PEM.2 Short-time Fourier transform(STFT)is adopted for time-frequency analysis on the mean value of bridge load and response,which clarifies its evolutionary rules in resonant and non-resonant condition and comes to conclusion for the resonance-inducing loading frequency component intensifying the resonant response of bridge.3 The probability distribution of the train-bridge interactive vibration response is studied,which helps to derive the theoretical model for probability distribution of the bridge displacement,dynamic coefficient,train response and wheel load reduction rate,and provides some suggestions for the the safety and stability of train-bridge system.