Dynamic Analysis Of A New Type Of Railway Steel-concrete Composite Trussed Bridge

In recent years, with the continuously developing of China's railway transportation, some steel-concrete composite trussed bridges, such as through steel truss composite bridge, have been built on the newly-constructed railway lines, especially on the high-speed and passenger railways. A new type of steel-concrete composite trussed structure is adopted on the Mawujinghe Bridge, which is located on the Xian-pingliang railway line. The structure composed of a triangular truss and a grooved concrete slab has been designed and used for the first time in China. Compared with the tranditional through steel truss railway bridge, it costs less steel, causes less running noise with larger stiffness, moreover, it is more rational considering performance under loading and more convenient to construction. The dynamic performance of the new structure is studied in this thesis, which is to provide reference and basis for its application on domestic ordinary passenger or freight railway and high-speed raiway. The main jobs and conclusions are presented as follows:A 3-D finite element model is established for the mentioned structure. In order to accurately simulate the grooved concrete slab, it is discretized into three kinds of elements respectively:the spatial beam elements, the shell elements and the 3-D solid elements during modeling. Then, the natural vibration characteristics of the bridge are calculated and analysed.For further research, the freight and passenger train loads are simpliflied as a series of moving concentrated forces which are ranged according to the actual spacings. on the basis of which the calculation model is built and the procedure is made to obtain vertical dynamic responses of the bridge.Finally, comparsion is made between the dynamic analysis results of the bridge due to simpliflied loads and the complete train loading which takes the effect of dynamic train-bridge interaction into consideration, through which the feasibility of the simplified calculating method is verified. The comparing results show that vertical dynamic deflections are close and time histories of the vertical displacement agree well by two calculating methods.