Arithmetic And Experiment Of Cable Tension For Pre-stress Spatial Steel Structure

The pre-stress spatial steel structure is a new type of structures which apply pre-stressed in spatial steel structures. By adding some high strength cables which are pre-stressed in spatial steel structures, it can take full advantage of the elastic strength of steel, improve the load capability of structures, reduce the structure distortion and achieve the aim of saving steel and cost. The geometric configuration and structural behavior of pre-stress spatial steel structures are critically related to the process of construction, which depend on more advanced construction technology.Firstly, this dissertation reviews the history and practical application of pre-stress spatial steel structures and discusses the theory and characteristics of these structures. Moreover, the methods and types of adding pre-stressing force are introduced and the pre-stressed algorithm is discussed. The aim and contribution of this work are pointed in the final of this part.Secondly, a large displacement takes place during the construction of pre-stressed spatial steel structures, which is a geometrical nonlinear problem. The explicit formulation of cable stiffness matrix was deduced by means of the nonlinear incremental finite. The formulations were divided into two types, relating with the tension force and relating with the initial length of the cable, which provides a foundation for the subsequent tension force calculation.Thirdly, this dissertation presented a inverse analysis method for controlling the initial length of the cable. Starting from the pre-stressed state,the tension force was calculated by controlling the initial cable length. First, the initial status and the initial cable length were calculated by means of controlling the cable force and the internal force of all members in the pre-stressed state were obtained at the same time. Then, the batching tension force could be got by controlling the corresponding initial length of cable. This method is simple and distinct. And it does not need repeated calculations.Fourthly, this dissertation proposed a new concept on cable tension adjustment, which considers the problem of cable force deviation as the initial cable length deviation. The method calculates tension acted on cables by controlling the initial cable length. Finally, the cable tension adjustment of the reticulated shell-string structure was calculated.Fifthly, this dissertation proposed a calculation method for the accumulative sliding construction of pre-stressed spatial steel structures, which combines the construction mechanics with controlling the initial length of cable. At the meantime, the alteration rule of cable tension was generalized. The initial length of cable was calculated by means of controlling cable force for the whole structure. The internal force of each stages of structure was obtained by considering the corresponding load and restraint in the accumulative sliding process. By this means, cables are tensioned only once and the construction is simplified.Sixthly, this dissertation studied the tension subsequence of pre-stressed spatial steel structures. Tension of cables belongs to the optimization problem of discrete variable therefore the object function can not be explicit expressed. To solve this problem, the genetic algorithm was applied in optimizing calculation. Taking the minimum sum of tension acted on cables as the optimized aim, the method seeks a feasible sequence of tensioning cables, which satisfies process requirements in determinate structural layout, physical dimension and constraint condition.Seventhly, a series of experiments and projects were carried out for verifying the previous theory. First, the cable force control test of reticulated shell-string structure in 2.2m×4.6m was conducted using the arithmetic presented in the paper. Second, the numerical analysis during construction, the adjustment of cable forces and the changing of cable of the Beijing North Railway Station were conducted.Eighthly, the accumulative sliding process and pre-stressed tension construction technology of pre-stressed cylindrical reticulated shells coal storage of Xinxiang power plant was introduced, and the construction process was analyzed using the theory that was presented in the paper.Finally, the conclusions of this dissertation were addressed and the future work was proposed.