The Application Of The Grey System Theory For The Construction Control Of Long-Span Bridges

With the rapid development of China's traffic, more and more long-span bridges are needed to be constructed. The longer the span of the bridge, the more difficulties are there in the construction. The bridge construction control is an essential measure and step to ensure that the quality and safety are obtained during bridge construction, also to ensure that the final structural state is in agreement with what the designer requires.And it is necessary to do more research on the construction control technologies for the long-span prestressing concrete bridges.Self-erection system is applied to construction of most of modern long-span prestressing concrete bridges. In the process of construction, cantilever beam is changing continuously because of the gravity of concrete, the stretching force, the load and temperature variation etc. In order to ensure that two cantilevers constructing opposite can normally close up and that the bridge linearity can accord with design, flexibility deformation and internal force have to be monitored. The aim of construction monitoring is to forecast possible flexibility and stress of constructing girder according to the principle generalized from constructed girder and to compare with the theory data then adjustable measure can be put forward. On account of the complexity of flexibility deformation and its influence factors, it can't be exactly measured, so it is thought as a grey quantum. In theory, it is feasible that using grey system theory to forecast flexibility. On the basis of this theory, this thesis focuses on the study of the application of the grey system theory to the construction control of long-span bridges.Firstly, this thesis introduces briefly the development and the theories of the construction control technologies for long-span bridges. Then, on the basis of the constructing of Dengkou Yellow River Bridge, using the method based upon the grey predictive control system to forecast pre-camber of bridge segment, a more advancedcontrol system——grey predictive control system for the construction of long-spanPC bridges and programs that is used to calculate inflection of main beams' deflections and the elevation of formwork during the construction have been developed. The results indicate that the grey predictive control system is adapted to the construction control for the long-span PC Bridge. Finally, through the Graphical User Interfaces (GUI) of Matlab software to built, imports the sample vector, and trains the bride construction ANN, this thesis uses the method of grey system combining artificial net (G-BP) to forecast the inflection and stress of main beams during the construction.