Several structural types and application conditions of steel structures

1. steel structure generally has the structure, plan truss, spherical net frame (shell), cable membrane, light steel structure, tower mast and other structural methods.

1. Steel structure architecture

2. Truss

Truss (héng) frame (jià)(truss): a structure formed by connecting rods with screws on both sides. Trusses composed of metal rods generally have a triangular unit plan or indoor space structure, truss rods key to bear radial anti-pull or working pressure, so it can flexibly use material strength, in the span of a large compared to the solid web beam to save raw materials, relieve their own weight and expand bending stiffness.

The advantage of the truss is that the rod is the key to bear the tensile or working pressure, which can make full use of the efficacy of raw materials, save raw materials, and ease the net weight of the structure. Common steel trusses, concrete trusses, prefabricated concrete trusses, wood trusses, steel and wood trusses, steel-cement-soil trusses.

3. Spherical grid

The indoor space structure is formed by connecting multiple bars to each other according to a certain grid diagram. The basic units that form the grid structure are triangular pyramids, triangular prisms, cubes, truncated quadrangular cones, etc. This basic unit can form a triangular, quadrilateral, hexagonal, annular or any other type of body with a plan shape. It has the characteristics of indoor space bearing capacity, light weight, large bending stiffness, good seismic resistance, etc. It can be used for roof trusses of stadiums, cinemas, exhibition halls, waiting halls, stadium stands, canopies, hangars, double-pillar spherical grid structures away from production workshop buildings, etc. The main disadvantage is that there are a large number of rods in the connection point, and the manufacturing assembly is more complicated than the plan structure.

4. Cable membrane

The cable-membrane structure system began in ancient times when humans lived in outdoor tents (housing buildings composed of support poles, ropes and fur). After the 1970 s, the birth of membrane materials with high strength, moisture-proof, light transmission and smooth surface, easy cleaning and aging resistance, coupled with the rapid development of scientific and reasonable engineering calculation, the structural system of cable membrane engineering has been started again, and now many of them have been used in commercial buildings in major regions such as seaside tourism, exhibitions, literary and artistic style, sports and so on.

5. Light steel structure

Light steel structure is a young and vitality of the steel structure system, has been widely used in general industrial and agricultural, commercial services, service-oriented engineering construction, such as office buildings, single-family villas, warehouses, sports venues, games and entertainment, holiday tourism engineering construction and low, high-rise residential and construction industry.

Light steel structure is also a relatively ambiguous vocabulary, generally there are two main understanding. One is chapter 11 "light steel structure of garden steel and small angle steel" in the current standard "steel structure design standard" (GBJ 17-88), which refers to the light steel structure made by garden steel and angle iron lower than L45 * 4 and L56 * 36*4. it is mainly used to manufacture small structures when concrete structure is not recommended in the era of construction steel shortage, and most of them are not used in general election, most of the revision of the steel structure design standards has been eliminated.

6. Tower and mast structure

For structures with relatively large height and relatively small cross-section, the level load (especially wind load) is an important basis for structural customization. According to its structure, it can be divided into independent vertical structure and pull rope mast structure, so the towering structure is also called tower mast structure.

Along with the development of industrial production technology, there are various types of towering structures. The Eiffel Tower in Paris was built in 1889 for the Paris Exhibition in France, with an absolute height of 300 meters. After 1921, wireless communication antennas and television antennas were installed on the tower, with a total height of 321 meters.

When selecting the 2. structure model, attention should be paid to the characteristics of different structural methods.

In the workshop, when there is a certain suspension load or large-scale moving load, it can be considered to abandon the portal steel frame and use the spherical grid frame.

Basically, in areas with heavy snow load, the roof curve graph should be beneficial to snowfall and slide (there is no need to consider snow load outside 50 degrees of disconnection). For example, the dolomite warehouse shed in the chemical plant uses a three-center round mesh shell, and nearly half of the total snow load is released compared with the sloping roof. Areas with large precipitation are similarly considered. When engineering construction allows, the layout of support points in the frame structure is more reasonable than the structure of simple connection points.

On buildings with large span covered by flat roofs, suspension bridges or cable-membrane structures with prefabricated components bent as the main body can be selected. In the steel structure design of high-rise residential buildings, steel concrete is often used to form the structure. In high-rise residential buildings with high seismic fortification intensity or very irregular high-rise residential buildings, it is not possible to choose the method of adding frames with poor seismic grade simply for the sake of economic development. The nearby super large SRC column should be selected, and the key is the structural system relying on the structure. In our country, more than half of this kind of high-rise residential buildings are the former one, which is not good for earthquake prevention.

The layout of the structure should be fully considered according to the characteristics of the system, load distribution characteristics and types, etc. Generally, the bending stiffness should be symmetrical, the mechanical model should be clear, and the influence degree of large load or moving load should be limited as much as possible, so that it can be conveyed to the basic by the most intuitive route, otherwise, attention should be paid to the distortion of the structure. The anti-side of the structure should have multiple procedural defenses. For example, the supporting point structure should be able to independently bear at least 1/4 of the total horizontal force,

The layout of the frame beam of the building plan of the structure can sometimes be adjusted to meet different needs. Generally, in order to reduce the cross section and lay out the frame beam along the short direction, this will increase the cross section of the main beam, reduce the height of the building, and sometimes the high-rise frame pillar can not stand it. At this time, the frame beam support point can be abandoned on the relatively short load-bearing beam to save the load-bearing beam and column.




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