考虑杆件失稳的单层球面网壳稳定性分析与试验研究

Stability analysis and test research of single-layer latticed dome considering bar buckling

为研究杆件初始缺陷和杆件失稳对网壳结构稳定性的影响,采用ANSYS有限元分析软件,引入杆件的初始缺陷,考虑杆件自身的屈曲破坏,确定其最不利整体缺陷模态和杆件缺陷模态。采用传统梁单元模型和精细化壳单元模型分别对采用圆钢管、矩形钢管、工字钢三种不同截面形式杆件的网壳结构进行稳定性分析,结果表明,考虑杆件缺陷的网壳结构稳定承载力大幅度降低。进行杆件轴力跟踪分析和杆件失稳传导分析发现,单层网壳的整体稳定破坏源于单根杆件的率先屈曲,杆件失稳瞬间迅速向相邻杆件传导,导致结构整体破坏。进行了K6(2)工字钢截面网壳的加载破坏试验,验证了预设缺陷的单根杆件失稳并传递诱发了整体破坏,且承载力受工字钢弱轴缺陷的影响很大。

In order to study the influence of bar initial imperfection and buckling on the stability of latticed dome, the FE model with bar initial imperfection introduced and bar self-buckling failure considered was built up in ANSYS software to find out the most unfavorable overall imperfection mode and most unfavorable bar imperfection mode. Beam element model and refined shell element model were adopted to calculate the ultimate load of single-layer latticed domes constructed with circular, box and I-shaped cross section bars respectively. The ultimate load is decreased very much when bar imperfection is considered. Continuous tracking of bar axial force near critical point and progressive buckling of bars shows that stability failure of whole structure starts with one bar buckling and bar failure transmits to the whole structure in a moment. Stability failure test of a K6 （2） dome with I-shaped cross section bars was carried out. It proves that the buckling of bar with preset initial imperfection leading the overall structure failure. The ultimate load is greatly influenced by the initial imperfection on the weak axis direction of I-shaped cross section.