Type selection design of steel structure
The steel structure usually has frame, plane (truss) frame, grid (shell), cable film, light steel, tower mast and other structural forms. The theory and technology are mostly mature, and some problems are not solved, or there are no simple and practical design methods, such as the stability of the latticed shell. In the selection of steel structures, different characteristics of them should be taken into account. In light steel workshop, when the suspension load or moving load is larger, the portal frame can be abandoned. Basic snow pressure big area, roof curve should be helpful for snow slide (tangent 50 degrees of domestic demand considering snow), such as the three circular shell. Nearly half of the total snow load is released, similar to those considered in areas with large rainfall. When the building permits, the support in the frame is better than the frame with the simple node. Among the buildings with large roof span, it is possible to choose the cable or cable membrane structures whose members are mainly tensioned. In the design of high-rise steel structures, the steel-concrete composite structure is often used. In the high or very high earthquake intensity, it is not necessary for the economy to choose the core of the earthquake resistance and the outer frame. The surrounding Mega SRC column should be chosen, and the core is the supporting frame system. More than half of this kind of high-rise in our country is the former, which is disadvantageous to earthquake resistance.

The arrangement of steel structures should be considered in terms of system characteristics, load distribution and properties. Generally speaking, stiffness must be uniform. The force model is clear. Limit the influence of large loads or moving loads as much as possible and transfer them to the base by the most direct route. The distribution of anti lateral support between columns should be uniform. The centroid should be close to the line of lateral force (wind shock) as close as possible. Otherwise, the torsion of the structure should be considered. The resistance of the structure should be multi line.

The arrangement of the floor plane and the secondary beam of the frame structure can sometimes adjust the direction of its load transfer to meet different requirements. Usually in order to reduce the cross section along the short time to decorate beam, but it will make the girder section increase, reduce the floor height of the top edge of the pillar, sometimes too much, the beams of the main girder is shorter on the secondary beam and beam column to keep the sacrifice.