A Study On Stress-Free Construction Control Of Concrete-Filled Steel Tube Arch Bridge

The concrete-filled steel tube arch bridge developed very rapidly due to the advances in span length of bridge and attraction in asthetics. However very few studies were performed to carry out the research on construction control of these concrete-filled steel tube arch bridge.The stress-free method is one of the construction control method, it utilizes the stress-free states to make a connection between the process stage and the final stage, and has the advantages due to its clarity, simplicity, fast computation, and more freedom in construction work.Therefore, the stress-free method was selected to carry out the research on the concrete-filled steel tube arch bridge, and the following tasks has been performed:1. The origin and stepwise development of the concrete-filled steel tube were introduced, then a detail review about the development in construction control and stress-free method that used in construction control was carried out.2. The basic theory about stress-free method was introduced, and the mainly two basic parameters were:stress-free length and the stress-free curvature. Then the characteristics of the stress-free method was introduced, and the main advantages of this method were compared with other method, And the application of the stress-free method in concrete-filled steel tube arch bridge was clarified.3. Influence matrix was used to optimize the cable forces by using the technique of rigid cables, then by considering the influence of shrinkage and creep of the concrete and the live load, the final results obtained were satisfactory for the bridge, and the stress-free curves of the steam, the tube arch and the stress-free length of the cables can be all gotten.4. Then genetic algorithm and the BP Neural Network were combined together, and both were jointly used to identify the paramenters.5. The changes in curves for steel tube arch, beam and the cable force in the final stage caused by the stress-free length of the cable at various locations were pointed out and then some conclusion were drawn.6. The changes in the final stage caused by the stress-free curves of the steel tube arch and the beam were pointed out and then some conclusion were drawn.