| With the rapid development of China’s passenger dedicated railway, the span of railway bridges is increasing. The most representative bridges among them are Tianxingzhou Bridge (a cable-stayed bridge with the main span of504m) and Dashengguan Bridge (a steel truss arch bridge with the main span of336m), both of which are built to cross the Yangtze River in the plain area. But when the railway line crosses deep mountainous gorges, cable-stayed bridge and steel truss arch bridge are limited by the construction site conditions and it is difficult to transport them. So, concrete arch bridge become the first choice for the large-span railway bridge in the mountains for its stiffness, bearing capacity, less influences by the change of temperature, harmony with the environment and many other advantages. Research shows that there are only six bridges of over the span of300m at home and abroad, all of which are highway bridges. There is no precedent on passenger dedicated railway. How to build large-span concrete arch bridge with high standards in the mountain area is an important research topic which we have to face now. In this paper, based on Beipanjiang River Bridge (Concrete Arch Bridge with the main span of445m) on the passenger dedicated railway from Shanghai to Kunming, the researches on structure selection, static behaviors during the construction process (static behavior, long-term shrinkage and creep of concrete, and nonlinear stability) and train-bridge coupling vibration are carried out. The main contents are presented as follows:(1) The research achievements related to the structure type of large-span concrete arch bridge at home and abroad is reviewed. Then, the key mechanical problems of large-span concrete arch bridge for passenger dedicated railway built in the mountain area are put forward, and its theoretical framework for design is summarized systematically.(2) The theory of bridge conceptual design is discussed. Based on it, the structure selection of large-span reinforced concrete arch bridge is carried out from the three aspects:reasonable structure system, construction method and main design parameters. Then, the selection principles of economic and reasonable structure type, optimized construction scheme and main design parameters are put forward.(3) The key problems for the rigid-frame construction method are put forward. After that, the stress histories of rigid-frame and outer wrapped concrete of main arch during the whole construction process are determined. Besides that, the principles of camber setting are analyzed.(4) The certainty analysis for the background project is carried out. Combining the MC90shrinkage and creep model with Latin Hypercube Sampling technique, the random analysis of long-term shrinkage and creep effect for large-span reinforced concrete arch bridge are made and the down deflection value is predicted.(5) Structural nonlinear stability during the whole construction process is studied. In the calculation model, the influences of geometric nonlinearity, material nonlinearity and ultimate bearing capacity of a single component on structural stability are taken into consideration. The safety factors of nonlinear stability during the whole construction process are given to determine the most unfavorable case, and its global stability is evaluated.(6) The influence of width and height of main arch on the train-bridge coupling vibration is studied to determine an economic and reasonable cross-section size of main arch. After that, the residual shrinkage and creep deformations and temperature deformations are added to the track irregularity, and its influences on the running performance of high-speed train are analyzed. |
