新型六杆四面体扭网壳的构形、静力和稳定性能

提出了一种基于投影平面为四边形的六杆四面体单元组成的新型扭网壳(简称六杆四面体扭网壳),研讨了六杆四面体扭网壳结构的构形,它构造简单,节点和杆件数相对较少,网格抽空率高,兼有单层和双层网壳的优点.针对上、下弦节点为半刚接半铰接六杆四面体单块扭网壳作了静力和线性与非线性稳定性分析,结果表明上弦杆全部受压,下弦杆全部受拉,腹杆除周边一、二圈局部杆件受压外大部分也都受拉,各类杆件内力变化幅度很小,有利于杆件截面选配,提高材料的利用效率.结构的整体刚度好,结构的双非线性稳定系数对比于相应特征值屈曲系数降幅很小,用钢指标优越.这类网壳结构在两种网格抽空方式的单块扭网壳、三种形式的四块组合型扭网壳和一种两块组合型扭网壳中有推广应用的前景.

Configuration, Static and Stability Analysis of Torsional Lattice Shell Composed of Six bar Tetrahedral Units

A new type of torsional lattice shell composed of six bar tetrahedral units is proposed in this paper. The configuration analysis shows that its form is simple because of the comparatively fewer members and the higher evacuation ratio. The shell has advantages both of single layer and double layer shells. Both static and stability analyses of the lattice shell with semi rigid joints are carried out in this paper. It turns out that the upper chord members all carry loads in compression while the lower chord members all carry loads in tension. The web members are mainly in tension except for the ones close to the boundary. The members can be designed using similar sections due to the little variation between their internal forces, which makes the structure design convenient and helps improve the material using efficiency. The integral rigidity of the structure is good; its nonlinear stability coefficient is just a little smaller than its eigenvalue of the first mode. The steel consumption is comparatively small. This new structure can be applied in single torsional shells with two evacuation schemes, three kinds of torsional shells composed of four single shells and one kind of torsional shells composed of two single shells.