The basic unit of the spherical lattice is a regular triangular cone composed of 3 chord bars 3 diagonal bars, that is, a tetrahedron. A triangular cone can be placed either directly inversely.
Triangular cone grid: connect the angles of the triangular cone with the angles, so that the plane diagram composed of the upper lower chord is of positive triangle type, which is called triangular cone grid.
Honeycomb triangle-cone network frame: this network frame is also composed of triangular cone elements, but the connection mode is that the upper chord the ventral chord are located in the same vertical plane, the upper lower chord nodes all collect six rods, which is a kind of common network frame with few nodes gathering rods.
Because the length of the compressed chord is shorter than that of the compressed chord, the force is reasonable less steel is used. However, the shape of the upper chord is hexagonal, which brings some difficulties to the roof design.
The node of the grid
1) The nodes of the network frame should make the structure simple, reasonable stress, clear force transmission, easy to make, easy to install save materials. Try to make the rod wire converge at the nodes to avoid the influence of eccentricity.
2) The structure connection of nodes shall have sufficient stiffness strength, at the same time, the structure of joint points shall conform to the calculation assumption as far as possible, so as to reduce avoid secondary stress internal force variation caused by unreasonable structure of nodes.
3) The connection nodes of the grid can be divided into welded steel plate node, welded hollow ball node, bolt-ball node, steel tube cylinder node steel tube drum node according to its structural form.