Study On Displacement Influence Matrix-based Identification Method For Prestress Loss Of Cable-supported Structures

During the construction and use of cable-supported structure,prestress loss of cable will occur to a certain extent.In the design of a structure,prestress loss is usually calculated in conformity with the corresponding codes and regulations ignoring the prestress loss caused by vibration and other external conditions,which results in a big difference between the design value and the actual one and affects the safe use of the structure.Therefore,it is very important to perform real-time monitoring and estimation of the prestress loss of the cable and to further evaluate the structural health.There is a corresponding relationship between the deformation and the prestress loss of the cable-supported structure;based on the principle of the influence matrix,this dissertation reveals the relationship between the deformation of the cable-supported truss structure and the prestress loss of the cable,and puts forward the establishment method of the displacement influence matrix of the cable-supported structure;taking the beam string structure roof of a high-speed railway station in the north as the research object,the proposed identification method of the prestress loss of the cable-supported structure is verified.The main research contents and conclusions are as follows:(1)This dissertation summarizes the calculation methods and detection technology of prestress loss at home and abroad,and analyzes the limitations of current calculation theory and detection technology.(2)This dissertation systematically introduces the mechanical propertiesof cable-supported structure including its characteristics and engineering application advantages,and foucuses on the prestress loss factors as well as their calculation method for the whole life cycle of the cable-supported structure from the construction and installation to the delivery and operation,and sorts out the relatively mature technologies of the prestress detection of the cable-supported structure at present.(3)The principle of displacement influence matrix coupled with its solution method is introduced.Based on the principle of displacement influence matrix,the method of establishing the displacement influence matrix in the truss string structure is presented,and the prestress loss is solved by the least square principle.After analyzing the influence of prestress loss on displacement in detail,the selection principle of the deformation observation point is obtained followed by the establishment of a preliminary judgment method for the prestress loss of the single frame.Besides,the influence of unit prestress loss a% on the identification value of prestress loss in structure is discussed.(4)Midas/gen is utilized to establish an analytical model for the non-column-platform canopy of a high-speed railway station in the north of China,and the feasibility of the method based on deformation displacement influence matrix in the identification of prestressed loss of tensioned structures is verified.