Analysis And Application Of Construction Mechanics Of Large Complex Steel Structures

Lots of new mechanical problems have emerged in the construction of large complex steel structures. In this paper, several key mechanical problems in the construction of steel structures are intensively studied, and the numerical results obtained are used directly to the construction of several actual projects. The main research work covered in this paper includes:(1) The principles of element's"death","floating"and"birth"for the element birth and death technology are studied theoretically. Another construction simulation method, the step-by-step modeling technology, is also discussed. The construction of the new CCTV headquarters is simulated by using the element birth and death technology and its internal force and deformation in the construction is given.(2) Several computational procedures, forward iteration method, backward iteration method and stepped comprehensive iteration method, for determining the pre-set deformation value of steel structures are proposed. The stepped comprehensive iteration method is applied directly to determine the manufacture and erection pre-set deformation values of the new CCTV headquarters where the influence of the settlements of the foundation is involved in the analysis.(3) A jack element model, a jack-gap element model and a jack-contact element model for simulating removing temporary supports of large steel structures are proposed respectively, where the jack element model is used to simulate removing temporary supports of the National Stadium.(4) Gliding cable element for simulating accurately the cable-sheave structures is discussed systematically, and its convergence is improved by the continuation Newton method. Analytical procedures for simulating the construction of the cable-sheave structures are discussed.(5) Two methods, elliptic simplified method and optimization iteration method, for determining the equilibrium state of the steel structures during their hoisting process are proposed. And the latter can accurately simulate the variation of the mechanic and geometric state of the structure during the hoisting process.(6) A secondary solution technology for determining the pre-stressed state and unstrained state of the cable structures is proposed, and the effect of the elastic deformation and self-weight of the structure can be involved in the analysis automatically. At the same time the manufacture configuration of the members can be obtained.