Research on Mechanical Behaviours of New Joints of Single-Layer Reticulated Shells
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摘要: 针对空间网壳结构提出了一种适用于矩形杆件的新型焊接端板节点. 为研究该节点的力学性能,制作了一个1∶2的缩尺模型进行静载试验研究,试验得到了节点荷载-应变曲线、荷载-位移曲线及破坏模式,结果表明节点应力水平较低,构造合理;在对有限元分析结果进行验证之后,分析了节点变形、破坏形态、应力应变分布及传力机理随节点端板厚度t2与杆件壁厚t1之比、水平夹角α、平面外角度β的变化规律,分析结果表明,该节点形式有较高的承载能力,其中水平夹角α对节点极限承载力影响较大,且在60° 前后影响作用不同;最后,基于有限元分析结果提出了该类型节点的极限承载力计算公式,可供设计参考.Abstract: A new kind of welded end-plate joint for a reticulated shell with a rectangular cross-section rod was proposed. To investigate the mechanical behaviour of the proposed joint, a test model at a scale of 1∶2 was designed and subjected to static loading tests. Load-strain curves, load-displacement curves, and failure modes were obtained, showing the joint’s performance to be low stresses at a reasonable level of detail. After validating the results of numerical models, the effect of the ratio of end-plate thickness (t1) to tube thickness (t2), the angle between the tubes α and the out-of-plane angle β on distortion of the joint, failure mode, and strain distribution were analysed. The results showed that the joint possessed a good load-bearing capacity; the angle α has a significant impact on this index, with 60° being a critical point. On the basis of the finite element analysis results, a formula that could provide a reference for design work was introduced for calculating the bearing capacity of the joint.
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表 1 材性试验结果
Table 1. Material properties of the test specimens
厚度/mm 屈服强度 极限强度 弹性模量 6 0.345 0.440 180 10 0.323 0.494 180 表 2 分析参数
Table 2. Parameters for analysis
参数 取值 α/(°) 30、38、45、60、68、75 β1-β2-β3/(°) 0-0-0、2-3-4、4-4-4、4-6-8、8-8-8 t1/mm 6、7、8 t2/mm 6、8、10、12、14、16 表 3 节点破坏模式及条件
Table 3. Failure modes of joint and conditions
项目 破坏模式A 破坏模式B 破坏模式C 破坏模式D 破坏模式E α α ≤ 60° α ≤ 60° α ≤ 60° α > 60° α > 60° t2/t1 t2/t1 ≤ 1.00 1.00 < t2/t1 < (1.50~2.00) (1.50~2.00) < t2/t1 较小 较大 破坏位置 端板及杆件壁屈曲 近节点区杆件壁屈曲 杆件1、2和3屈曲 端板及杆5端部屈曲 杆件5屈曲 类别 节点区破坏 节点区破坏 杆端破坏 节点区破坏 杆端破坏 节点PEEQ图 注:表中“节点PEEQ图”仅截取部分显示. -
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