Travel Comfort Evaluation For Large Span Bridges Based On Rail Line Band Separation

High-speed railroad are rapidly developing in transportation at home and abroad,because high-speed railroads have the advantages of faster speed,better safety,strong conveying force,comfort and convenience,and lower energy consumption.With the increasing speed of high-speed railroad train operation and the construction of high-speed heavy-duty railroads,the interaction between trains and tracks is becoming stronger and stronger.Track geometry irregularities are the source of excitation in the wheel-track system and are the main cause of rolling stock vibration and wheel-track forces,which leads to track geometry irregularities becoming an important factor affecting train comfort and safety.It is particularly important to consider the smoothness and comfort of train operation under the effect of track unevenness.At present,there is much interest in the study of the travel comfort of large-span bridges in China.The paper discusses the evaluation of the travel comfort of large-span bridges based on the separation of track alignment bands for the control objective of travel comfort.Specific research content is introduced as followed:(1)By analyzing the relationship between the acceleration of different components of bridge deformation and the maximum acceleration of vehicle vibration,as well as the frequency response function of vehicle acceleration on the amplitude of track displacement,the feasibility and separation limits of long and short wave separation are determined.Then introduce the approximate solution of the long and short wave partial acceleration.The approximate solution of the short wave acceleration can be obtained by the vector value of the string measurement,and the approximate solution of the long wave acceleration can be obtained by the curvature calculation.Next,the signal leakage problem encountered in the current long and short wave filter separation is introduced,and the leakage problem is effectively reduced by improving the existing filters.(2)Analysis of existing track unevenness detection methods,static detection methods can not reflect the interaction of the bridge when the train crosses the bridge,and the existing dynamic detection methods also have defects in accuracy.In order to further improve the detection accuracy,a three-point dynamic chord measurement method on the bridge is proposed in this paper.By comparing the similarity of different detection methods and the time course curve of train vibration response,it is found that the vector value of dynamic chord measurement on the bridge with three measurement points can better reflect the law of train acceleration response.(3)The relationship between the acceleration combination of random track unevenness and short waves of additional deformation of bridges is studied.The results show that the acceleration of randomly uneven track and short wave of additional bridge deformation basically satisfy the combination of "square and open square(SRSS)".Then replace the acceleration in the combined formula with the acceleration approximation solution,and then calculate and derive.And find that the acceleration approximation solution of the randomly uneven track and the additional deformation of the bridge short wave also satisfy the "square and open square" combined relationship.Similarly,the combined relationship is extended to the acceleration combination of short and long waves.And the results show that the approximate solutions of the acceleration of three types of track deformation,namely,randomly uneven track,short wave with additional bridge deformation and long wave with additional bridge deformation,satisfy the "square and open square" combined relationship.Finally,the combined equation is used to invert the comfort control standard with the amplitude of the chord measurement method as the index.In order to achieve a more simple and convenient control of travel comfort of large span bridge.