螺栓滑移引起的铝合金板式节点网壳变形研究

板式节点螺栓滑移会引起铝合金网壳结构发生明显变形，变形主要取决于节点轴向变形，可通过节点轴向刚度模型来模拟螺栓滑移.为考虑实际工程中螺栓尺寸的随机误差，提出节点轴向刚度的随机多折线模型，分析发现，考虑螺栓尺寸误差计算得到的网壳挠度，可采用理想四折线模型结果拟合. 基于轴向刚度四折线模型，分析网壳挠度随螺栓预紧力的变化规律，发现当预紧力高于特定临界值时，网壳变形很小，反之网壳挠度会迅速增大. 进一步分析发现：最大网壳挠度与螺栓孔径差、网格环数呈正比，受跨度、矢跨比和支座形式影响较大，与杆件截面及节点板尺寸、荷载大小相关性较小. 基于此，提出螺栓滑移引起的最大网壳挠度计算公式，并对工程中常见的拉铆钉和普通螺栓，给出孔隙优化建议.

Study on Structural Deformation of Reticulated Shells with Aluminum Alloy Gusset Joints Caused by Bolt Slippage

The bolt slippage of gusset joints can cause structural deformation in aluminum alloy single-layer reticulated shells. The magnitude of deformation depends on the axial displacement of gusset joints, thus, a reasonable axial stiffness of gusset joints can model the bolt slippage to calculate the structural deformation. A stochastic-polylines model is proposed for the distance of bolt slippage influenced by the random error of bolt geometries. It is found that the structural deflection calculated with the stochastic-polylines model can be fitted by that calculated with an ideal four-polylines model. Based on the four-polylines model, a case study is used to research on the structural deflection which varies with bolt pre-tightening force. It is found that if pre-tightening forces are larger than a limit value, the structural deflection ranges with a small amplitude, otherwise it increases distinctly. Further numerical analysis concludes that the maximum deflection approximately linearly varies with the number of grid rings and the gap between bolt and hole. And it is also affected distinctly by the structural span, the ratio of structural height to span and support type, but uncorrelated with the geometry of member section and joint gusset and the scale of loads. Then, a formula to compute the maximum deflection is proposed. And the optimum diameters of holes in gusset joint are lastly suggested for the widely used bolt and rivet connections.