Study On Influencing Factors And Suggestive Value For High Speed Railway Simply Supported Beam

Bridge dynamic coefficient is the dynamic amplification effect index of the bridge, which is the comprehensive reflection of dynamic characteristics and dynamic interaction status of the train-track-bridge system. The influence factors and laws of bridge dynamic coefficient are analyzed and dynamic coefficient suggestive value of the high speed railway bridge is researched. It is of great theoretical value and engineering significance to ensure that bridge’s dynamic reliability and train operation safety. Based on the train-track-bridge system vertical vibration analysis theory, the influence factors of dynamic coefficient of the bridge are analyzed in this paper, and proposed formula is proposed for dynamic coefficient of the high speed railway32m simply supported beam. The main contents and conclusions of this article are as follows:1. Based on the principle of the total potential energy with stationary value in the elastic system dynamics and the rule of "set in right position" for formulating system matrix equation, the vertical vibration matrix equation of the train-ballast track-bridge and the train-ballastless track-bridge system are established. The corresponding computer programs of the system are developed with Fortran90language, the correctness of procedure is verified through the classic numerical examples.2. The internal force formula of beam element considering dynamic factors in the bridge model of ballast track and ballastless track is derived. Displacement and internal force dynamic coefficient in different positions are calculated and the law of bridge dynamic coefficient is summarized: Displacement dynamic coefficient in the three-quarters of the bridge spans can represent displacement dynamic coefficient of simply supported beam; Moment and shear force dynamic coefficient in the three-quarters of the bridge spans can represent internal force dynamic coefficient.3. Based on the train-track-bridge system of vertical vibration analysis program, the impact of various factors on bridge dynamic coefficient is discussed in detail considering three aspects of the vehicle, rail and bridge. The main factors are fundamental frequency of bridge, driving speed, vehicle length and axle load, bridge span. As the increase of bridge fundamental frequency, the speed value corresponding to rapid growth point of bridge dynamic coefficient increases, and operation speed within the scope of the dynamic coefficient could reduce. There is a roughly linear relationship between operation speed and bridge dynamic coefficient.4. Displacement and internal force dynamic coefficient are respectively calculated Which are in the32m high speed railway for250km/h ballasted track simply supported box girder and for350km/h ballastless track simply supported box girder. The present results compared with the Japanese Shinkansen dynamic coefficient:In this paper the calculation of bridge dynamic coefficient slightly lower than Japan’s Shinkansen dynamic coefficient and values between the two is basically the same trend. In view of the above two box girders, using the linear regression method, a function of the high-speed railway32m simply supported beam dynamic coefficient and the speed of traffic is fitted out, which used as the recommendation of dynamic coefficient formula.