Research On The Limited Capacity Of Rigid Large-span Steel Space Structures

Large-span steel space structures can be categorized into three systems: the flexible large-span steel space structures, the rigid large-span steel space structures and mixed large-span steel space structures, based on their form and mechanical properties. Members of reticulated shells or arch structures of the rigid system must sustain great amount of axial forces which can induce overall stability of structures. Such systems which has poorly stability property become the work of the thesis.Based on an extensive literature survey, this thesis summarized the research history and the updated situation from modeling, equilibrium path tracking, defect influence, and testing research, pointed out the deficiency of the traditional formula on checking the limited capacity of space structures and then put forward the main wok of the thesis: how to calculate the limited capacity correctly and how to establish the checking formula of the structures.How to calculate the limited capacity correctly of the structures is one of the research keystones of the thesis. Because only on the fully understanding of all kinds of influence factors of the structural limited capacity, one can ensure the exactness of the model and the efficiency of the result, and estimate the capacity exactly. The main factors influence on the limited capacity was categorized as instability modes, instability spreading, struts instability, shape deviation, joint stiffness, and bearing system. Based on these, proposed procedure of determining limited capacity of space structure was brought up.Instability zone spreading outwards result from interior force redistribution after member buckling is the key cause of whole structure instability. Thus effective strut model is critical to calculate limited capacity correctly. A few mechanic models and methods for describing post-buckling and hysteresis performance were discussed in detail, and a more reasonable strut model was developed on the theory of plastic hinge which was verified by some numerical examples.For the limited stability of space structure, the practical erection deviation is an important initial defection. Defect sensitivity of single-layered reticulated structure was investigated using strut model. The influence of initial geometric defects was understood anew. Some proposals on modeling initial defects and the defect figure were offered.Joint stiffness is one of the key factors influence on structural limited capacity, and is considered differently according to the structure system and instability type.