网架结构大直径螺栓球节点锥头承载力计算式

Formula for bearing capacity of conical head in large-diameter bolted spherical joints of space grid structures

建立弹塑性有限元模型,对大直径螺栓球节点试验中容易破坏的锥头进行数值计算,试验结果验证了有限元模型的适用性。考虑了影响锥头承载力的各种主要因素,进行了相应的参数分析。揭示了大直径锥头具有底板壁厚塑性贯通、锥壳壁厚塑性贯通和局部承压破坏等三种破坏模式,掌握了螺栓直径d、钢管直径D5以及有关锥头的径向厚度t、底板厚度H、锥头斜率k、底板受荷面积比S等各种几何参数对锥头承载力的影响效应。基于多元回归分析,提出了大直径锥头前两种破坏模式的承载力计算式。与试验结果相比,计算式较为准确可靠,可应用于工程设计。

An elasto-plastie finite element model was established and used for numerical calculation of conical heads in the large-diameter bolted spherical joints which frequently failed during the previous experiments carried out by the authors. The experimental results validated the finite element model. Main factors influencing the bearing capacity of the conical head was considered and the relevant parametric study was carried out. Three kinds of failure modes were discovered in a large-diameter conical head, i.e. the bottom plate through-thickness plastifieation, the shell through- thickness plastifieation and the local bearing failure. The effects of the geometric parameters such as bolt diameter d , tube diameter D5 and radial thickness t , bottom plate thickness H , slope of conical head k and loading area ratio of bottom plate S of conical head on the bearing capacity of a conical head were understood. The formulas for calculating the bearing capacity corresponding to the former two failure modes were proposed based on multiple regression analysis. Compared with the experimental results, it is concluded that the formulas are accurate and reliable and can be used in engineering design.