新型插盘式脚手架的试验和数值模型研究

Study of experiment and numerical model on a new disk-type steel scaffold

为研究一种新型插盘式脚手架的力学性能,对三跨两步脚手架体系进行足尺试验研究,得到其极限承载力、破坏模式及顶层节点的荷载—位移曲线。这种新型脚手架的承载力显著高于传统扣件式脚手架,破坏模式为单根竖杆的屈曲破坏。采用通用有限元软件ANSYS对试验中的脚手架体系建立三维杆系计算模型,考虑材料的弹塑性及结构的几何非线性,进行非线性极限承载力分析;并引入转角弹簧和轴向弹簧单元分别模拟梁柱节点半刚性以及支撑与节点的连接刚度,通过改变弹簧单元的刚度对整个结构进行参数分析,得到与试验结果较吻合的数值分析模型。试验和数值分析结果对比研究表明:支撑连接刚度对结构的极限承载力和抗侧刚度影响显著;但梁柱节点的半刚性对其影响不大,为计算简便,梁柱节点可按铰接处理。

A two-storey steel scaffold was built and tested to failure in order to examine the structural behavior of a new disk-type steel scaffold. A non-linear finite element model with both elastoplastic material property and geometric non-linearity was established to evaluate the load carrying capacities of the scaffolds under idealized boundary conditions. Moreover, rotational spring elements and axial spring elements were used in the FEM analysis to simulate the semi-rigidity of joints and the connection stiffness of braces, respectively. The numerical model was examined through an extensive parametric study by changing the stiffness of the spring elements. Comparisons between the results of the experiment and the FEM analysis demonstrate that the effect of the connection stiffness of braces on increasing the load carrying capacity and the lateral stiffness of the steel scaffold system is evident, while the effect of the semi-rigidity of the joints is relatively insignificant, which implies that the beam-column joints can be simplified as hinges.