The planar shape of the grid is flexible, and can be designed into various shapes. According to the different settings of the webs can be divided into: cross truss system, square pyramid system, the triangular pyramidal system and other systems. The truss chord called boundary perpendicular to put the grid, called diagonal grid boundary bias. World in large and medium-sized roof have been successfully built a lot of network structure, such as Canada and Japan Expo, Chicago congress hall and London hangar, plane size, the total amount of steel is also more economy, the former Soviet Union is still the grid with a pre-stressed. In short, the grid structure has become one of the new structure of the more common of the modern world. China from the 1960s began to study and use in recent years, due to the rapid development of electronic computing technology, to solve the high-order grid structure statically indeterminate structure calculations, prompting the network structure in terms of the type aspects and practical engineering applications development soon. Mainly used the span in public buildings, such as gymnasiums, hangars, clubs, galleries and waiting hall, small and medium-sized industrial plant also began to promote the use of. The greater the span, the use of the advantages and economic effects of such a structure is also more significant