Program Design And Research Of The Complete Process Of Prestressed Steel Structure With Cables

Among the prestressed steel structures, the prestressed steel structure with cables is prestressed by tensioning the cables, and the flexible cables are the main or assistant members to bear the loads. The structure is the most widely used in the structure systems of the prestressed steel structures.Based on the geometry nonlinear finite element theory, the program of the complete process of the prestressed steel structure with cables is compiled. Through the computing of the great span beamstring structure and the cable net structure, the validity of program is proved. And the bearing capability of the two structures is researched by the program.The two nodes 3D link element, two nodes 3D beam element and five nodes 3D cable element are formulated based on the geometry nonlinear finite element theory. And the global stiffness matrices, the equilibrium equations and the element forces are obtained. Then the flow chart of the nonlinear analysis is designed.The basic analysis methods of the prestressed steel structure with cables are completely discussed. Firstly, the form finding of the cable-beam system and the cable net system is summarized, and the flow chart is designed. Secondly, the methods of simulating tensioning such as'the equivalent forces method','the reducing temperature method','the initial strain method'and'the simulating jack method'are contrasted and analyzed. The judgment based on the force equilibrium condition and the displacement harmony condition is presented to estimate the validity of these methods, and the importance of the analysis model's integrity is also presented. The essence of'the reducing temperature method'is deeply discussed by the author. Subsequently, the issue that the essence of the method is tensioning the reduced cable and making the cable end and structure end meet in the same point to prestress the structure is presented. According to the explanation, the relationship of'reducing temperature'and the practical tensioning process is obtained and the drawn length of the cable can be accurately computed. Secondly, obtaining the accurate forces of the cables by'the reducing temperature method'is discussed and the iterative approach is designed to use in the program.The program is compiled by Fortran 90 computer language in the Fortran PowerStation 4.0 program environment. The program adopted the two nodes 3D link element, two nodes 3D beam element and five nodes 3D cable element, and used the load increment method and Newton- Raphson method in order to make the high geometry nonlinear structure converge. The program included three function modules: pre-disposal module, compute module and post-disposal module. The compute module can do the complete process analysis of the prestressed steel structure with cables (form finding analysis, tensioning analysis and bearing load analysis). Through computing the structures composed of links, beams and cables and contrasting with the literature's results, the validity of the program is proved.By using the program, the great span beamstring structure and cable net structure is computed and investigated. The Haerbing conference and exhibition center's beamstring structure is computed and the program results are contrasted with the practical testing data.At the end, the useful results and suggestions are presented.