去索对无环索弦支穹顶静力性能的影响规律研究

无环索弦支穹顶结构的下部预应力索支体系较为繁冗，影响其整体受力性能且给施工造成一定困难，需要进行合理优化。以某体育馆60m跨屋盖为实例，研究去索对无环索弦支穹顶结构静力性能的影响。针对原结构下部三层预应力索支体系，设计了四种去索方案,综合分析不同去索方案对上部网壳结构总应变能、整体结构最大竖向位移和承载力的影响程度，确定最优去索方案。模拟最优去索方案对无环索弦支穹顶结构进行静力性能参数分析，研究撑杆高度、拉索索力、初始几何缺陷对结构刚度和承载力的影响。结果表明：去索位置越靠近中心，对上部单层网壳总应变能影响越小，对结构刚度和结构承载力的削弱越小，节约用钢量越少；去除第三层索对上部单层网壳应变能、结构刚度和承载力影响很小，建议在优化时优先考虑去除第三层索；第一层撑杆高度和第一层拉索预应力的增加可以使结构整体结构刚度显著变大，对结构承载力影响不大而对失效模式影响较大；第二层撑杆高度的变化对结构刚度无影响，对结构承载力和失效模式影响很小；第二层拉索索力的变化对结构刚度和承载力影响不大而失效模式影响较大；建议在优化时优先考虑调整第一层拉索和撑杆；初始几何缺陷对结构承载力影响较大，初始缺陷越大结构承载力越低，而对结构失效模式影响不明显。

Influence on static performance of loop-free suspen-dome after removal of cables

The layers of the prestressed cable-strut system of the loop-free suspen-dome are relatively tedious, which affects the overall mechanical performance and causes certain difficulties to the construction, and needs to be optimized reasonably. Taking a 60 m-span loop-free suspen-dome in a gymnasium as an example, the effect of cable removal on the static performance of the structure was studied. According to the number of layers in the prestressed cable-strut system in the original structure, the influence of the cable removal schemes on the total strain energy of the reticulated shell, the maximum vertical displacement, and the structural bearing capacity was studied to determine the optimal cable removal scheme. The static performance of the optimal cable removal scheme was analyzed parametrically, and the influences of the height of the strut, the cable load, and the initial geometric imperfection on the structural stiffness and the bearing capacity were studied. The results show that the closer the cable removal position is to the center, the less effect on the total strain energy of the reticulated shell, the smaller the weakening of the structural stiffness and bearing capacity, and the less steel is saved. The removal of the third layer has little effect on the total strain energy of the reticulated shell, the structural stiffness and the bearing capacity. It is recommended to give priority to the removal of the third layer during optimization. The increase in the height of the struts and the cable loads in the first layer can significantly increase the overall structural stiffness, with little effect on the bearing capacity and a greater influence on the failure mode. The change in the height of the struts in the second layer has no effect on the structural stiffness, and has little effect on the structural bearing capacity and failure mode. The change of the cable loads in the second layer has little effect on the structural stiffness and the bearing capacity, but has a greater influence on the failure mode. It is recommended to give priority to adjusting cables and struts in the first layer during optimization. The initial geometric imperfection has a greater influence on the bearing capacity. The greater the degree of imperfection is, the lower the bearing capacity is, but the effect on the failure mode is not obvious.