Dynamic Responses Of Track Bridge And Simplified Running Safety Of Vehicles During Earthquakes

Track bridge has become an important part of urban rail transit because of its small footprint, space utilization, smooth high orbit characteristics. With the rapid development of urban rail transit, people have paid more and more attention to the safety of vehicles, earthquake is an important factor affecting vehicles safety on rail bridges,and China is a country with frequent earthquake, so the safety of vehicles under earthquake is a great matter must be concerned.To solve above problems, created vehicle-track-bridge dynamic response analysis program based on the existing vehicle-track-bridge system dynamic equation, analyzed the dynamic response of a railway bridge and the simplified analysis method of vehicles safety with the prestressed concrete simply supported box type track bridge and box type continuous beam bridge as the research object. The concrete research content is as follows:(1) To study the effects of seismic waves on the spectral characteristics of bridge rail vehicles safety, inputed the real seismic waves, artificial waves, harmonic to the vehicle-track-bridge dynamic response analysis program respectively, got the vehicle-track-bridge dynamic response under three seismic waves, and comparative analysis of the results showed that the vehicle-track-bridge dynamic response under the artificial waves is more similar to the dynamic response under the real seismic waves, so use the artificial seismic waves as the inputting waves;(2) According to the earthquake intensity and period provided in " China Earthquake Parameters Map", generated artificial seismic waves of different intensity and period with trigonometric series, and inputted them to the vehicle-track-bridge dynamic response analysis program respectively, to analyse the vehicle-track-bridge dynamic response;(3) Taken the Japanese vehicles safety evaluation index as the vehicles safety assessment standards under the earthquake, got the dynamic response of the bridge when the vehicles in derailed critical state, and taken it as bridge vibration limits; got the bridge vibration limits under the seismic waves of different intensity and frequency with the method of statistics, and draw the bridge vibration limit curves, obtained the curve mathematical expression with Lagrange interpolation, hoped to be referred in actual bridge seismic design;(4) According to the vehicle motion in dangerous situations simplify the strict vehicle-track-bridge model to get the simplified vehicle-track-bridge model; using the force balance principle to get the vehicles safety analysis method based on the simplified model, and according to the analysis results based on strict vehicle-track-bridge model, got the simplified vehicles safety evaluation standard.