Research Of Motor Collision Loads And Dynamic Responses Of High Speed Train-bridge System And Running Safety Evaluation Of Trains Subjected To Motor Collision Loads

With the rapid development of transportation home and abroad, the bridge span becomes longer and the train speed becomes faster, and the problems of bridge vibration become progressively. Meanwhile, as the traffics become increasingly busy, collisions between vehicles and bridges crossing roadways also become more serious. In this dissertation, the bridge vibration that induced by collision load and its influences on the running safety of high-speed train are studied, which is funded by the National Key Basic Research Program "973" project " Basic research of dynamic evolution and service safety of infrastructure of high-speed railway (Grant No.2013CB036203)" and the National Natural Science Foundations "Dynamic responses of railway bridges subjected to motor collision loads and running safety control of vehicles (Grant No.51308035)". The detailed contents and highlights of the study include:(1) The serious accidents of bridges subjected to motor collision and the related research situation home and abroad are reviewed, and the necessity of research toward running safety of high-speed train on bridge subjected to motor collision load is elaborated. The research contents and general analysis methods of train-bridge dynamic interaction problem are summarized, and the significance and research basis of this doctoral dissertation are introduced.(2) The design methods (general average method, local average method, simplified pulse method, equivalent displacement method), numerical simulation and experimental results of motor collision loads are summarized, by referencing the highway and railway bridge design codes and the related researches home and abroad. The characteristics of motor collision loads, including duration time, maximum values and loading positions are analyzed, which provides an important supporting to determine the motor collision loads for dynamic analysis of train-bridge interaction system.(3) The dynamic analysis models of train-bridge interaction system subjected to collision loads are established, and the computer code is written, where the vehicle submodel is established with multi-rigid-body dynamics, the bridge submodel is established with modal superposition method, the vertical wheel-rail force is defined with the wheel-rail close contact assumption, the lateral wheel-rail force is defined with the Kaller’s Creep Theory, and the collision force is simulated as nodal dynamic load. Moreover, a new simplified method base on train-vehicle model is proposed, which is compared with the complex model method. Finally, the results are conservative and the calculation efficiency is proved suitable to the engineering for case study.(4) Based on the dynamic coupling test platform of train-rail-bridge, the influence on bridge and running safety of train under lateral collision force is researched though model experiment qualitatively. From observing, the dynamic strain at the bottom of pier, dynamic displacement and acceleration at top pier, lateral displacement and acceleration of beam, and car-body acceleration of the train greatly increse when the bridge is subjected to motor collision, which may threaten the train running safety.(5) Field experiments with served critical bridges were carried out to measure the influence on bridge and running safety of train under lateral collision force. Considering the expensive and destructive of actual collision, the lateral hammers forces are used to replace motor collision force. The test results also indicate that the dynamic response increase sharply and which threaten the train running safety. According to the responses and input excitation, the transfer function of bridges is obtained. Motor collision force is multiplied with transfer function in the frequency domain. After IFFT the above product, the response obtained approximate the act response under motor collision in the engineering field, assuming the bridge is in a linear state. And transient finite element model analysis using ANSYS is established to compare with the IFFT method.(6) With the two analysis models and the computer code, by taking the south approach bridge (32m simplified box girder) of Nanjing Dashengguan Yangtze River Bridge as a case study, whose main pier is subjected to motor collision load, and considering a normal passenger ICE3train and the Germany irregularity spectrum as calculation conditions, the running safety indices of the train are calculated through computer simulation. Some of the calculated results are compared with the measured results obtained in the complex model, which prove the proposed simplied method is more conservative and efficient in the engineering application.