Optimal Design Of Multi-Stage Pre-Stress Steel Structure Based On Structural Reliability

Pre-stress steel structure, a new type of structure in which combine pre-stressed with steel structure. Adding some high strength bar in steel structure, and forcing these bars pre-stress can improve the structure capability, reduce the structure weight. Pre-stressed steel structure can take full advantage of elastic strength of steel, furthermore, multi-pre-stressed steel structure can repetitively make use of the steel structure's elastic strength. It is more economic than single pre-stress. So, it's important to research pre-stressed steel structure in theory. This paper is supported by the National Natural Science Foundation of China.An optimal model of multi-pre-stress steel structure is established on the base of that of pre-stress steel truss. The former model of staged loading and staged optimization is improved, in which the value range of pre-stress restrict in restrict equation. It provides the theoretical base for the loading time of multi-pre-stress and the value of pre-stress. And examples analyzed with linear programming and full-constrained methods prove the convergence effect well.An optimal model of pre-stress steel truss is presented based on reliability. The reliability index is replaced by subentry coefficient in optimal model restrict equation, and deal with corresponding restrict conditions with applied expressions. Linear programming associated with full-constrained methods are used in this paper, which improve the profit of multi-pre-stress steel structure design and the reliability of structures as well as model and arithmetic. The optimized section area considering reliability is in some degree different from that without it, which can be applied in practice.The examples of three bar truss and parallel chord truss with biggish span are analyzed on the conditions of reliability or not, the results of which prove the model and method proposed in this paper are feasible.The study of this paper show that considering reliability in pre-stress steel structure is necessary and can answer the structure design criterion as well as standard demand. Besides, the research methods provide the theoretical base for applying the reliability in practical pre-stress steel structure optimal design.