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Why do we need steel structures and what are their classifications?

2022 / 06 / 30

In recent years, national and local governments have issued relevant policies on prefabricated steel structure buildings. The Ministry of Construction has carried out more than 30 research projects on steel structure buildings and built many pilot projects. At the same time, many universities and enterprises have also joined in the research of steel structure building system and key technologies. As an important system of assembly building, steel structure building will usher in new development opportunities and challenges.

What is steel construction?

With steel or steel plate made of basic components, according to the requirements of use, through welding or bolt connection and other methods, in accordance with a certain law of the bearing mechanism called steel structure. Steel structure is widely used in various engineering construction, such as steel bridge, steel workshop, steel gate, various large pipe containers, public buildings, high-rise buildings and so on.



1. Greatly saving construction time, construction is not affected by the season;

2. High strength, light weight, high safety and affluence of components, reduce building cost;

3. Fire prevention, steel is a kind of building material that does not burn;

4. Good seismic performance, easy to transform in use, flexible and convenient, bring comfort and so on;

5. Increase the use area of residential space, reduce construction waste and environmental pollution;

6. Building materials can be reused to promote the development of other new building materials industry;

7. In line with the national sustainable development strategy, low-carbon, green, environmental protection and energy conservation are key industries supported by the state.


Classification of steel structure buildings

According to the structural stress characteristics, steel structure buildings can be roughly divided into portal frame structure, space truss (HENG) frame structure, string beam structure, chord supported dome structure, grid frame structure and multi-storey structure.

1. Portal frame structure:

Portal frame is a traditional structural system, the upper main frame of this structure includes frame oblique beam, frame column, strut, purlin, tie bar, gable frame, etc.

The steel structure of light building with portal frame has the characteristics of simple force, clear force transmission path, quick fabrication of components, convenient factory processing and short construction period, so it is widely used in industrial and civil buildings, such as industry, commerce and cultural and entertainment facilities. Portal steel frame light house steel structure originated from The United States, and has become a structural system with relatively perfect design, manufacture and construction standards after nearly 100 years of development.


2. Space truss structure

Space trusses, or spherical truss, are lightweight rigid structures that form a geometric pattern. The ball frame usually uses a multidirectional spacing, which is a structure composed of tension rod and pressure rod. The structure is in a three-dimensional state of stress. No matter what kind of truss, it can bear loads from all directions, and it can play a better role in buildings with large seismic collapse distance, which is often used in public buildings.


3. String beam structure

In modern times, tensive-string beam structure was clearly proposed by Professor M.Saitoh of Japan University, which is a new hybrid roof system different from the traditional structure. The tension beam structure is a kind of hybrid structure system formed by winding rigid member, flexible cable and connecting struts in the middle. Its structure composition is a new self-balance system, a long-span prestressed space structure system, and also a relatively successful creation in the development of hybrid structure system. The structure system is simple, the force is clear, the structure forms are diverse, and the advantages of rigid and flexible materials are fully played. Besides, the manufacturing, transportation and construction are simple and convenient, so it has a good application prospect.


4. Chord-supported dome structure

The chord-supported dome structure is similar to the girder structure in that the tension of cables is used to produce a supporting force on the beam to reduce the stress on the trabecula, but there are significant differences between the two: the chord-supported dome cable is linear tension, while the chord-supported dome cable is circular tension;

Therefore, this structural system is suitable for similar circular roof, such as Beijing Bicycle Velodrome, Anhui University gymnasium, etc.


5. Grid structure

Grid structure is a kind of space bar system structure, the stress bars are connected by nodes according to certain rules. The joints are generally designed to be hinged, and the rod is mainly subjected to axial force, with a relatively small cross section size. These spatial confluence of the rod and support each other, the force of the rod and support system organically combined, so the material economy. Because the structure combination is regular, the shape and size of a large number of rods and nodes are the same, which is convenient for factory production and site installation.


6. Multi-storey structure

(1) Frame structure

The frame is composed of columns and beams, bearing vertical force and lateral force;

The rigid frame has poor lateral force resistance and large lateral deformation. It is generally suitable for structures with less than 20 floors.

The column generally adopts box steel column or concrete filled steel tube column;

The concrete-filled steel tubular column (CFST) is filled with concrete in the round pipe or box column, which not only has the advantages of steel structure, but also makes full use of the good compressive properties of concrete.

(2) frame shear wall structure

It is similar to the frame support structure, but the support is replaced by shear wall to resist lateral force;

Shear wall is generally concrete plate or steel plate, or steel mix combination structure, than the support has better lateral stiffness, layout is more flexible, can be suitable for higher building structure.

(3) Tube in tube structure

By the heart tube, frame tube and truss tube combination, generally the heart tube inside, frame tube or truss tube outside, by the internal and external tube together to resist the horizontal force. The shell surrounded by shear wall is called solid belly shell, and the shell formed by regular arranged window holes is called frame shell; The four walls of the cylinder body are made up of the truss formed by the vertical rod and the inclined rod.

(4) Beam tube structure

Bundle tube structure is the combination tube structure. When the building plane is large, in order to reduce the deformation of the external wall under the lateral force, the building plane is arranged according to the modular grid, so that the external frame-type cylinder and the internal vertical and horizontal shear walls (or densely arranged columns) become the combined cylinder group.

This greatly enhances the stiffness and lateral force resistance of the building. The beam tube structure can be composed of any architectural shape, and can adapt to the needs of the body combination of different heights, enriching the appearance of the building. The 110-story Sears Tower in Chicago, THE United States, uses a beam tube structure.



Policy support, industrialization demand, and the increase of steel production have greatly promoted the development of steel structure construction. Steel structure building because of its own powerful assembly properties can be very good to adapt to the development of The Times, we have to do is to give full play to the technical advantages of steel structure building itself, to develop more assembly steel structure building system in line with the current development needs.

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