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国内某展览中心屋盖采用单层单向悬索结构,其中悬索用钢板带代替;定长悬索通过压重后变形而获得初始预应力。先通过单索抛物线理论确定符合建筑使用功能和美观效果的初始态以及相应屋面压重;然后结合施工方案,以初始态为基础,通过不断调整预起拱值的大小反推假定的零状态,进行施工全过程正分析,直到压重下悬索的变形位置达到建筑控制位置为止。结果表明,确定悬索零始态的关键在于边桁架张拉的水平距离和悬索的初始长度;通过试算确定的零状态模型,变形后悬索位置与建筑控制几何位置之间的差距满足预先设定的不大于10mm的要求;所采用的找形分析计算方法不仅能得到零状态以便施工放样,同时还可得到杆件相应初始内力,为分析屋盖结构承受其他外荷载提供条件。此外,还比较了典型节点的位置、典型构件的轴拉力随施工过程的变化规律。
The roof of an exhibition center in China adopts a single-layer unidirectional suspension structure, in which the suspension cables are replaced by steel strips; the fixed-length suspension cables obtain the initial pre-stress after being deformed by the pressure. First, through the theory of single-cable parabola, the initial state and the corresponding roof pressure in line with the function and aesthetic effect of the building are determined. Based on the initial state, the assumed zero state is deduced by adjusting the size of the pre- The whole process of construction is being analyzed until the location of the deformation of the suspension cable reaches the building control position under pressure. The results show that the key to determine the zero state of the suspended cable lies in the horizontal distance of the side truss tension and the initial length of the cable. The gap between the position of the deformed cable and the geometric position of building control satisfies The presetting requirement is not more than 10mm. The method of form-finding analysis not only can get the zero state for the construction lofting, but also obtain the initial internal forces of the bars, which provide the conditions for analyzing the roof structure to bear other external loads. In addition, the position of typical nodes is compared with the variation of axial tensile force of typical components with the construction process.