Grid structure:

A space structure in which a plurality of bars are connected by nodes in a certain grid form. It has the advantages of space force, light weight, high rigidity, good seismic performance, etc. It can be used as a roof for buildings such as stadiums, theaters, exhibition halls, waiting halls, stadium stands, awnings, hangars, and two-way large-pitch workshops. The disadvantage is that the number of bars that are connected to the nodes is large, and the fabrication and installation are more complicated than the planar structure.

 

Classification:

There are many types of grid structures, which can be classified according to different standards.

First, according to the structure of the grid itself can be divided into: single-layer grid structure, double-layer grid structure; three-tier grid. Among them, the single-layer grid and the three-layer grid are suitable for the case of small span (not more than 30m) and especially large span (more than 100m), and there are few engineering applications in China.

Second, according to the construction materials are divided into: steel grid, aluminum grid, wooden grid, plastic grid, reinforced concrete grid and combined grid (such as the combination of steel grid and reinforced concrete panels, etc.), Among them, the steel grid has been widely used in China, and the combined grid can also be used as the floor layer structure.

Third, according to the support situation can be divided into: peripheral support, four-point support, multi-point support, three-sided support, opposite side support and mixed support form.

Fourth, according to different composition methods, the grid can be divided into four categories:

1. Cross truss system grid;

2. Triangle cone system grid;

3. Four-corner cone system grid;

4, hexagonal cone system grid.

The fourth classification method is a popular classification method in China.

 

Form:

There are 11 types of grid structures that have been applied to different degrees in China. The following 11 types of grids are introduced from the aspects of composition and characteristics.

First, the cross truss system grid

The first major category is a grid structure consisting of two or three sets of planar trusses, called the cross truss system grid. This is one of the simplest and one of the earliest forms of grid construction. It evolved and evolved on the basis of cross beams. The upper and lower chords of this type of grid are the same length. The web can generally be designed as a "pull rod system", that is, the long rod (slant rod) is pulled, the short rod (vertical rod) is pressed, and the angle between the slant rod and the chord should be between 40 degrees and 60 degrees. Among them, the vertical rod is shared by each group of plane trusses. There are two forms of this type of grid commonly used.

The cross truss system is further divided into two-way grid and three-way grid.

Second, the triangular cone system grid

The second broad category is suitable for buildings of square shapes such as squares, rectangles, triangles, trapezoids, hexagons, octagons, and circles.

It is divided into: triangular cone mesh frame, evacuated triangular cone mesh frame, honeycomb triangular pyramid mesh frame.

Three, four pyramid system grid

The third category is a grid structure consisting of four-cornered vertebral bodies. There are five forms: square square pyramid net frame, square square pyramid net frame, diagonal quadrangular cone mesh frame, checkerboard quadrangular cone mesh frame and Star shaped quadrangular cone mesh.

Four, hexagonal cone system grid

The fourth category is a grid structure consisting of a hexagonal cone (hectahedron) called a hexagonal cone system grid. Its basic unit element is 6 chords, 6 chords consisting of hexagonal cones (inverted or upright). One of the main forms of this type of grid is the hexagonal cone grid.

 

Structure introduction:

Rod design and node construction

The cross-section of the members of the grid structure shall be determined based on the strength and stability calculations. In order to reduce the calculation length of the pressure bar and increase its stability, measures such as adding a sub-bar and a support rod may be adopted. The plate type grid frame made of steel and the nodes of the double-layer shell type grid frame mainly have three forms: a cross plate node, a welded hollow ball node and a bolt ball node. The cross-plate joint is suitable for the grid structure of the steel bar, and the connection between the rod and the gusset plate is welded or high-strength bolt connection. The hollow ball joint and the bolt ball joint are suitable for the grid structure of the steel pipe rod. The joints of the single-layer shell-type grid should be able to withstand the bending internal force. Under normal circumstances, the steel consumption of the joints accounts for 15-20% of the steel used for the entire steel grid structure.