Study On Composite Beam Cable-stayed Bridge Quasi-unstressed State Control Method

With the continuous development and progress of the social economy,the construction demand of long-span bridges is increasing day by day.The composite girder cable-stayed bridges have strong competitiveness in long-span bridges,and their steel-concrete combined main beams give full play to steel and The respective advantages of concrete materials have become more and more widely used in the construction of long-span bridges.The composite girder cable-stayed bridge is a complex high-order statically indeterminate structural system.The main girder is composed of different materials,and the upper structural members are of various types.The design calculation and construction control are more complicated than the single-material main girder cable-stayed bridge.In particular,the staged construction control objectives are not clear and the control accuracy requirements are high.The main content of this paper is based on the stress-free state control method to study the design calculation and construction control of the composite girder cable-stayed bridge.Firstly,this paper investigates the development and advantages of the stress-free state control method,analyzes the construction control of various types of cable-stayed bridges,and then proposes the problems of the staged construction control of the composite cable-stayed bridges.;Secondly,the phased construction of the beam structure and the cable structure and the internal force state of the primary forming are studied.Deriving the mechanical formula,analyzing the state error,proposing a solution,and then introducing the basic principle of the stress-free state control method;Thirdly,the calculation case of the 48m+96m+48m double-tower composite girder cable-stayed bridge is introduced,and the method of determining its reasonable bridging state is explored.The calculation method of deriving the unstressed state quantity of each component is analyzed,and the calculation result is theoretically derived.Compared with the results of the one-off model analysis,the correctness of the formula is verified.Then,the main points of construction control of the composite girder cable-stayed bridge are analyzed and analyzed.How to realize the installation of each component with its standard stress-free state during the phased construction process.For example,cable staying installation correction,steel main beam assembly line shape,bridge deck pouring state,process cable force optimization target and Helong section superimposedbeam installation control;Finally,relying on the actual project of the 185m+220m single-tower composite girder cable-stayed bridge in the Weinan Minjiang River Bridge,the research results are used to carry out the stress-free state control method under the action of concrete shrinkage and creep,using iterative convergence.The idea realizes the phased construction control into the bridge and the reasonable completion of the target state of the bridge,and extracts the construction control parameters in stages,guides the on-site construction,and achieves relatively good results.After carrying out the above research,this paper can accurately calculate the unstressed state of each component,and realize the standard unstressed state construction control of the composite girder bridge under the condition that the components are installed in a standard unstressed state.Later,relevant experience will be provided in the design calculation and construction control of the same type of bridge.