Study Of Structural Selection, Design And Analysis Of Large-span Steel Structures And Experiments For Some Key Joints

With the rapid development of airport terminals, high-speed railway stations, stadiums and other large pubic buildings in China, it brings higher requirements for large-span spatial steel structure designs and their construction technology, especially in fields of selection of structural system and critical connection design. However, current applicable structural codes can not completely meet the demands of engineering design. In addition, the problem of imperfect of design theories and methods as well as insufficient experiment data can cause unreasonable structural design and higher construction cost. Therefore, the researches for the structural selection of large-span spatial steel structures and experimental analysis of their vital connections are very important in both theory and engineering application.Current research work related to the large-span spatial structures in the world is summarized. In this thesis, based on three engineering projects, the structural selection and designs of large-span spatial steel structures and their key connections are studied by theoretical analysis, numerical simulation and experiments. The main work and contribution in the thesis are in the following.1) Structural selection and analysis of large span and space steel structures. For some test center of the large span and space steel structure, three consideration schemes of the structural system were firstly proposed. Then, by analyzing and comparing the structural performances and economical efficiency of the three schemes, the new type double-layer grid shell structure system, which conposed of inclined plane truss arch, was established as the executing scheme. Furthermore, the mechanical analysis and design of the selected structural system subjected to wind load, temperature and earthquake actions were performed in detail by the finite element method and some strategies. The results of the analysis show that the selected structural system has satisfactory structural performances and economical efficiency. Moreover, it is good that the designed structure has uniform stiffness distribution in vertical and horizontal directions, obvious space effect, the reliable global stability and capacity of resisting progressive collapse.2) Structural selection and analysis of large span steel-pipe truss structures. By analyzing structural systems of existing airport terminals and considering the structural characteristics of Hefei Xinqiao International Airport Terminal, the idea of a new type of steel-frame structure was proposed in the present thesis, which consists of spatial steel-pipe truss with curved box-section beams and box-section columns. By analyzing and comparing the structural performances and economical efficiency with two conventional steel-frame structures, the new type structure system has better structural properties and more econmy. Then the complete structural system was established based on the results of the mechanical analysis and earthquake-resisting analysis. By the evaluation according to the complete design indications and all standard code requirements, the new structure system has good properties for resisting earthquake and wind as well as nice ductility. Meanwhile, the analysis of multi-point output response of the structure under considering the traveling wave effect has been implemented.3) Selection and experiment research of the transfer connections of large-span steel structure. For the large-span steel structure project of Hefei Xinqiao International Airport Terminal, three design schemes for the key transfer joint connection between spatial steel-pipe truss and box-section columns are established. By the comparisons of the load capacity and economical efficiency, one of the three schemes was selected because of the simple construction, continuous stiffness and convenient construction. Then, the selected transfer connection was designed in detail according to the requirements of bearing capacity, structural stability and strength by the multiple finite element analysis and improvement of the joint structure. On the other hand, experimental research of bearing capacity of the selected joint scheme was done. Compared the results between the finite element analysis and experiment, it indicate that the selected joint connection has good ductility and sufficient safe capacity besides meeting the demands of structural strength and stiffness. The present joint connection has been first applied in the structure of Hefei Xinqiao International Airport Terminal.4) Experimental research and numerical simulation of bearing capacity of the pin connections of large-span structure under heavy load. The pin connection was first applied to the structure of Shandong Zhouchen international conference and exhibition centre, which is in the case of heavy floor load. The pin connection between steel column and steel truss in the large structure was taken as the testing object. In the experiment study, four groups of specimens with 1:2 scaled dimensions, the testing device and loading system are established. The tests of bearing capacity and failure for the specimens of the pin connection were then carried out. Thus the bearing capacity and failure pattern were obtained. On the other hand, the finite element analysis was also used to simulate the loading process of the joint test. The experimental results of the bearing capacity of the pin connection were in the agreement with ones of the finite element analysis. As a result, the structural performance of the pin connection was accurately acquired. Therefore, the present research results showed that the proposed pin connection subjected to the design load cases has high safety factor and strength potential, which meets the requirements of the bearing capacity and normal work.Through the tests and analysis of the bearing capacity of the transfer connections and pin connections, their mechanical properties and strength potentials are obtained and the design method is proposed. By the above work, the structural selection strategy and design method of large-span steel structures according to the requirements of the structural performances is also established. Consquently, the analysis method and testing technique established by the present thesis provided successful experiences for the constructions of the same kind of the large-span steel structures and the key connections. The present results can be also used as the technical data of the structural codes related to the large-span steel structures.