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The structure of the grid is affected by many factors, such as the fabrication and installation method of the grid, span size, steel index, etc., all of which affect the determination of which grid form to be adopted to a certain extent.

1. For example, the welded joints and the truss composed of plane truss system are more convenient to make than the truss composed of quadrangle cones. Two - direction orthogonal grid is more convenient than two - direction oblique grid and three - direction grid. The tetrahedral mesh is more convenient than the tricone mesh.

2. If the installation method does not adopt overall lifting or lifting, but adopts strip or block installation, or adopts high-air sliding method, choosing three kinds of orthogonal positive laying network frame, such as two-direction orthogonal laying network frame, four-angle cone network frame and four-angle cone network frame, is more advantageous than choosing oblique laying network sprinkler.

3. The calculation shows that the span size has little influence on the selection of grid structure. However, the long-span grid is generally an important structure. At present, the grid structure composed of two orthogonal grid systems, two orthogonal diagonal grid systems and three directional grid systems is widely used in China. Because the design and construction experience of these several kinds of large span network frame is richer, the technology is more skilled. The general structure of the three-way grid, the three-angle cone grid, the hexagonal cone grid and the general structure are more complex, and the amount of steel used is large, so it should be less used in the small span.

4. Steel index is an important symbol to measure the selection of grid structure.