Theoretical Analysis And Design Calculation Of Steel Structures Strengthened By Prestressing

Steel structure has many advantages, so it is used widely in various fields. When its strength, rigidity and stability can't be satisfied, it must be strengthened and rehabilitated.At present, the plan of strengthening steel structure can mainly be divided into three methods, method of enlarging member sections, changing calculation diagrammatic drawings and strengthening by prestressing. Among them, prestressing is an effective method of strengthening and rehabilitating steel structure. But the interest in strengthening is far less than the new construction. As a result, the study, experiment and practice still have a little.The practice in steel structures strengthened by prestressing is countable in our country. Furthermore, there are no systematic research findings on it. Only one or two articles involve it, but the depth and range is not too enough. So it has a very important theoretical value and actual significance to study and generalize the theories it concerned systematically, especially for some types of steel structures in common use.Being based on the theories of prestressed steel structure and some clauses in code for design of steel structures, absorbing some advanced fruits about concrete structures strengthened by external prestressing and being combined with two calculated examples of strengthening, a more systematic theoretical analysis of steel structures strengthened by prestressing is gone on in this article and the calculating theory and design method is put forward. The research work and some fruits got in the article are as follows.1. The post-tensioned prestressing system suited for steel structures strengthened by prestressing is selected. Combined with the new code for design of concrete structures and some theories of concrete structures strengthened by external prestressing, the analysis and modification on the calculation of loss of prestress is taken on and the calculating method of it is presented.2. The feature and calculating principle that steel structures strengthened by prestressing have is introduced here. Based on limit-state design method in steel structure design principle, the principle and method of phased strengthening design of steel structures strengthened by prestressing is represented here. 3. The calculating method, optimum strengthening design and application of axial tension and compression members strengthened by prestressing is analyzed and discussed.4. The calculating theory, design method and some factors affecting strengthening design of steel beams strengthened by prestressing are overall analyzed. An example of strengthening of a steel beam is calculated and analyzed by comparison. There is also a profound study on the mechanics performance and secondary moment of the continuous steel beams strengthened by prestressing. 5. Based on the theory, software design is gone along by VB language and verified by an example.6. The scheme of the layouts of prestressed tendons and the design method of steel trusses strengthened by prestressing are analyzed and researched, meanwhile, an example is calculated and analyzed.