第4章+网壳结构.ppt

* （3） Triangular pyramid system(三角锥体系) Latticed Shell Structure 双曲抛物面网壳在几何学上的特点是其曲面的形成方式属移动式，具有直纹性，即其曲面是由无数根斜交的直线组成。通过一定的组合，双曲抛物面网壳还可以发展出不同的造型。 Orthogonal-ortholaid type 正交正放类 Orthogonal-diagonal type 正交斜放类 Hyperbolic Paraboloid Latticed Shell 双曲抛物面网壳 4.1.4 Types of Hyperbolic Paraboloid Latticed Shell 双曲抛物面网壳类型 Latticed Shell Structure 1. Orthogonal-ortholaid type(正交正放类) 组成网格为正方形;用单层形式时，在方格内设斜杆；采用双层形式时可组成四角锥体。 The grid of this type is square. Diagonal members should be added when single layer is adopted and square pyramid can be formed system when double layer is adopted. Latticed Shell Structure 2. Orthogonal-diagonal type(正交斜放类) 如图 c）所示，杆件沿曲面最大曲率方向设置，抗剪刚度较弱。在第三方向全部或局部设置杆件，如图 d）、 e）、f）所示，可提高它的抗剪强度。 Latticed Shell Structure Latticed Shell Structure 根据跨度大小、刚度要求、平面形状、支承条件、制作安装以及技术经济指标综合考虑。 Some indexes like spans, stiffness, shapes, supporting conditions, installment, technique and so on should be included when selecting the forms. 1. Double layer latticed shell structures can adopt hinged joints while single layer latticed shell structures should adopt rigid joints. 双层网壳可采用铰接节点，单层网壳采用刚接节点. 4.1.5 Form-selection of Latticed Shell Structure 结构选型 Latticed Shell Structure 2. Double-layer latticed shell structures are suitable for long-span structures while the single -layer latticed shell structures can be applied to small or medium span structures. 双层网壳适合大中跨度的结构，中小跨度可采用单层网壳。 3. Large vector height should be adopted when the span of the spherical and cylindrical latticed shells are long. However, when the span is small, hyperbolic paraboloid latticed shell can be used because of its small vector height. 跨度大时，宜采用矢高大的球面或柱面网壳；跨度小时，可选用矢高较小的双曲扁网壳或双曲抛物面网壳 Latticed Shell Structure 4. The structural with super stability should be adopted firstl. 优先采用结构稳定性较好的体系。 3. Boundary members with high stiffness should be set to bear the horizontal forces generated from the latticed shell and they can also be regarded as the comp