In contrast to single-storey steel structures, the wind loads (and seismic loads) of multi-storey steel structures are becoming increasingly important as the height of the building increases. Therefore, for multi-storey steel construction, how to effectively bear the level of force is to consider the composition of the structure of an important issue. Under the action of the wind, not only should there be sufficient carrying capacity, but also should have a safe and stable stiffness, so that the top layer is not too large swing, to the feeling of discomfort.
The composition of the multi-storey steel structure has the following main systems:
(A) rigid frame structure
The beam and the column form a multi-layer and multi-span frame to bear the horizontal load. This structure has both the lateral displacement as the cantilever and the displacement caused by the interlayer shear force under the horizontal load, so the deformation is relatively large. It does not apply more than 20-30 layers. Between beams and columns should be made rigid connection. When the number of layers is no more than 10-15, semi-rigid connection may also be considered.
(B) with support structure
In the two columns between the set of bracing, the formation of vertical cantilever truss, the ability to withstand horizontal load than the frame structure is high. This structure is suitable for the 20-45 layer, its beam and the column can be made between the flexible connection, semi-rigid or rigid connection.
(C) tube structure
More than 60 layers of steel structure using cylinder structure is more economical, surrounded by four sides of the house are formed frame, a rigidity of the space truss system. This structure has been effectively used in 110-storey high-rise houses. Cylindrical structure can also not set the bracing, and in the surrounding four sides of the column arranged in a more dense, the formation of space rigid frame cylinder. It can be used to 80 layers of height.
Cylindrical structure can also be used inside the elevator shaft made of inner tube, and Jane together to bear the level of force, the middle of the other pillars are only subject to vertical load.
(4) Suspension structure
This system utilizes all the gravity and horizontal loads in the inner cylinder of the center of the house, with reinforced concrete or steel and reinforced concrete composite structures in the inner cylinder. There are overhanging trusses on the top of the cylinder, and the floor is hung with a high-strength steel rod on the frame. After the completion of the cylinder can be used to lift the steel structure, the entire project period is shorter.
Through the above analysis of the composition of the steel structure can be seen, the structure must be formed as a whole space, can effectively and economically bear the load, with high strength, stability and stiffness. If the main load-bearing components themselves have been formed as a whole, without additional support, can be very effective composition of the program. The suitability of the structural scheme and the conditions for the construction and material supply are also very relevant. In the actual project to be combined with the specific conditions of the basic use of the basic type. For example, in a multi-layer structure, the rigid frame structure and the support structure can be used together. The framing system may be formed in one direction, and in the direction perpendicular to its direction, the support system may be provided with support in the lower part and a frame in the upper part.
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