Appearance is different

It can be divided into two - layer plate - type structure, one - layer and two - layer shell - type structure. The members of plate type and double shell type are divided into upper chord, lower chord and lower chord, which bear tension and pressure. The members of the single-layer shell frame bear not only tension and pressure, but also bending moment and shear force. At present, most of the grid structure in China adopts plate grid structure.

form

The first type is composed of plane truss system, which has four forms: two-direction orthogonal net, two-direction orthogonal net, two-direction oblique net and three-direction net.

The second type is composed of quadrangle pyramidal units, which have five forms: positive quadrangle, positive quadrangle, oblique quadrangle, checkerboard quadrangle and star quadrangle.

The third type is composed of triangular pyramidal units, which have three forms: triangular pyramidal frame, evacuated triangular pyramidal frame and honeycomb triangular pyramidal frame. According to the shell type, the shell type is divided into cylindrical shell type, spherical shell type and hyperbolic paraboloid shell type. According to the materials used, the structure of the grid consists of steel grid, reinforced concrete grid and the combination of steel and reinforced concrete.