Experimental Investigation of a Fan-Shaped Assembled Joint for Curved Lattice Shells
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摘要: 提出了一种用于曲面网壳结构的新型扇形组合装配式节点,该节点主要由扇形子构件、中心区域肋板以及高强螺栓三部分组成。区别于传统的焊接节点,该节点主要部件由工厂预制,现场使用高强螺栓进行组装,不仅减少了焊接工作量,也避免了高空焊接,降低了施工难度和风险。此外,节点中心区域采用无盖板连接,充分体现了其半刚性特征,同时也便于后期检修。为探究该节点的受力特性,设计并完成了装配式节点试件和焊接节点试件的静力对比试验。试验针对两类节点的6个足尺试件,采取轴向、偏心以及横向加压三种加载方式,对比分析两类节点各关键部位应变分布规律、荷载-位移曲线、弯矩-转角曲线及破坏模式,考察了装配式节点的单向受压和弯曲性能,并得出其薄弱部位以及偏压作用的影响。采用有限元方法分析了各节点在单向受压和弯曲作用下的受力特性演化过程,并与试验结果进行对比。通过对扇形组合装配式节点和传统焊接节点进行试验和有限元分析,可以得到以下结论:在单向受压荷载下,扇形组合装配式节点表现出与焊接节点相同性能,即受力可靠且变形较小;加载全过程中,扇形组合装配式节点的轴向刚度与焊接节点非常接近;在轴向偏心荷载下,扇形组合装配式节点的轴向刚度明显下降,因此在实际工程运用中应考虑压弯组合作用对节点的影响;弯曲试验中,扇形组合装配式节点破坏过程分三个阶段:1)弹性阶段。弯矩小于81.5 kN·m时,节点表现出良好的抗弯性能;2)弹-塑性阶段。弯矩在81.5~142.6 kN·m时,抗弯刚度存在明显退化现象;3)塑性失效阶段。弯矩大于143 kN·m,高强螺栓受剪脆断,试件宣告破坏,因此提高此节点抗弯刚度的关键在于提高螺栓的抗剪能力。扇形组合装配式节点的有限元模拟和试验最终破坏形式相符,且应力分布规律以及弯矩-转角曲线整体均具有较高的吻合度。Abstract: A new fan-shaped assembled joint for curved lattice shell structure is proposed, which is mainly composed of three parts: fan-shaped component, central rib plates and high-strength bolts. Different from the traditional welded joints, the main sections of this joint are prefabricated by the factory and assembled on site using high-strength bolts, which not only reduces the welding work but also avoids overhead welding, and reduces the construction difficulty and risk. In addition, the joint is connected without cover plates, fully reflecting its semi-rigid characteristics, and also facilitating later maintenance. The static comparison experiment between the assembled joint and the welded joint was conducted for exploring mechanical characteristics of the joint. A total of six full-scale joint specimens were tested with the type and loading condition as test variables. The strain distribution, load-displacement curve, moment-rotation curve and failure mode of the key parts were analyzed, and the weak parts and the influence of bias pressure were obtained. The evolution process of mechanical characteristics under uniaxial compression and bending was analyzed by finite element method and compared with the experimental results. Through the experiment and finite element analysis, the following conclusions can be drawn: under uniaxial compression, the fan-shaped assembled joint shows the same mechanical performance as the welded joint, the force is reliable, the deformation is small, and the axial stiffness is very close during the whole process of loading. Under the eccentric compression, the axial stiffness of the fan-shaped assembled joint decreases significantly, indicating the influence of the compression-bending combination on the joint should be considered in the practical engineering application. In the bending test, the failure process of the fan-shaped assembled joint experiences three stages: 1) the elastic stage(<81.5 kN·m), in which the joint shows good bending performance; 2) the elastic-plastic stage(81.5-142.6 kN·m), in which the bending stiffness decreases markedly, and the rotation increases gradually owing to bolt slippage and deformation of the bolt hole wall; and 3) the plastic failure stage(>143 kN·m), in which the bolt is brittle and the specimen fails, indicating that the key to improving the bending stiffness of the fan-shaped assembled joint is improving the shear strength of the bolt. The final failure mode, stress distribution, and bending moment-rotation curve of the finite element analysis are in good agreement with those of the experiments.
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Key words:
- curved lattice shells /
- assembled /
- joints /
- axial stiffness /
- flexural stiffness
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