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通过对一个静置于地面的单弦杆网架进行预应力后张拉,得到马鞍形网壳.对鞍形网壳模型进行了竖向加载试验,静载施加于上弦节点,分级加载.测试了各级荷载作用下的杆件应变和上弦节点挠度,得到荷载-挠度曲线,从而得出该结构模型的竖向极限承载力.试验结果表明,轴力是杆件主要内力形式;杆件破坏现象较少,仅支座附近腹杆发生了轻微屈曲;在成形阶段部分上弦节点即进入塑性,节点承载力降低,在加载过程中易发生断裂破坏,进而引起结构刚度下降,削弱了结构竖向承载能力;由荷载-位移曲线看出该结构的主要破坏形式不是整体失稳.最后给出改进结构的指导思想是在不降低节点铰接特点的同时,设法提高其承载能力.
A saddle-shaped reticulated shell was obtained by prestressing and post-tensioning a single-chord net resting on the ground. The saddle-shaped reticulated shell model was subjected to a vertical loading test, applied to the winding node in static loading, and loaded in stages. The ultimate load-bearing capacity of the structure model is obtained from the strain of the bars and the deflection of the winding nodes under load at all levels. The test results show that the axial force is the main internal force form of the bars. Only a slight buckling occurs to the webs near the abutment. At the forming stage, some of the winding nodes enter into plasticity, the bearing capacity of nodes decreases, and the fracture damage occurs easily during the loading process, thereby causing the structural rigidity to drop, weakening the vertical load of the structure The main failure mode of the structure is not the overall instability.Finally, the guiding principle of improving the structure is to try to improve its carrying capacity without reducing the hinge characteristics of nodes.