Research On The Coupled Vibration Of Combined Highway And Railway Suspension Bridge Under Earthquake

With the acceleration of China’s urbanization, rail transit construction within the city sets off the boom. Suspension bridges have many superiorities such as large span, reasonable structure, safe and efficient construction, beautiful shape and so on, so they usually become the first choice for bridge type in many cities. China is a country prone to frequent earthquakes, which is a threat to the safety of bridges and the traffic on them. Therefore, it is necessary to study the coupling vibration of vehicle-bridge under earthquake. Taking Ji Jiang Changjiang steel box girder combined highway and railway suspending bridge as engineering background, this paper studies the vehicle-bridge coupled vibration of this bridge. The main work is as follows:1. The suspension bridge development, the analysis of bridge seismic response, the coupled vibration of vehicle-bridge and the vibration under earthquake are introduced briefly, importance and necessity of study on vehicle-bridge coupled vibration system under earthquake are also presented.2. Based on the principle of total potential energy with stationary value in elastic system dynamics and the rule of "set in right position" for formulating system matrixes, the vehicle vibration analysis model and equation are established; and the fine element dynamics model of the Ji Jiang Changjiang steel box girder combined highway and railway suspending bridge is also established.3. Based on the above analysis model, it analyzes the dynamic response of the bridge with the combination of single-line and double lines of vehicle B at different speeds. And the conclusions indicate that the traffic safety and comfort level meet the requirement.4. Inputting the E1(accidence probability of10%in50years) earthquake as an external incentive on the vehicle-bridge system, it analyzes the dynamic response of the bridge with the combination of single-line and double lines of vehicle B at different speeds under earthquake. The conclusions indicate that, under E1earthquake, the traffic safety can be assured and the results meet the requirement of Special Demonstration Techniques of Seismic Protection of Municipal Utilities (bridge engineering in cities and towns).