Steel structure knowledge | Main technical content of steel structure

‌ The main steel structure technology includes high-rise steel structure technology, space steel structure technology, light steel structure technology, steel-concrete composite structure technology, high-strength bolt connection and welding technology and steel structure protection technology.

According to the building height and design requirements, frame, frame support, cylinder and giant frame structure are adopted respectively, and its components can be made of steel, reinforced concrete or concrete filled steel tubes. The steel component is light in weight and good in ductility, and can be used as welded or rolled steel, which is suitable for ultra-high building. The rigid reinforced concrete member has high rigidity and good fire resistance, which is suitable for middle and high-rise buildings or bottom structures. Concrete filled steel tube is simple in construction and is only used for column structures.

The space steel structure has light weight, high stiffness, beautiful shape and fast construction speed. The spherical joint flat grid with steel pipe as the rod, multi-layer variable section grid and reticulated shell are the structure types with the largest amount of space steel structure in China. It has the advantages of large space stiffness, low steel use, in design, construction and inspection procedures, and can provide complete CAD. In addition to the grid structure, there are long span suspension cable structure, cable membrane structure and so on.

Light steel structure technology

The new structural form is accompanied by light colored steel plates made of walls and roof enclosures. By more than 5mm steel plate welded or rolled large-section thin-wall H-beam steel wall beam and roof purlin, round steel made of flexible support system and high-strength bolt connection composed of light steel structure system, column distance can be from 6m to 9m, the span can reach 30m or larger, the height can reach more than ten meters, with a steel amount of 20 ~ 30kg/m2. Now there are standardized design procedures and specialized production enterprises, good product quality, fast installation, light weight, less investment, construction is not subject to seasonal restrictions, suitable for a variety of light industrial plants.

The beam and column bearing structure composed of section steel or steel management and concrete members is a steel-concrete composite structure, which has been widely used in recent years. The composite structure has the advantages of both steel and concrete, the overall strength is high, the rigidity is good, the seismic performance is good, when the external concrete structure is used, it has good fire resistance and corrosion resistance. Composite structural members can generally reduce the amount of steel used by 15 to 20%. The composite floor and concrete-filled steel tube members also have the advantages of less or no mold support, convenient and rapid construction, and have great promotion potential. It is suitable for frame beams, columns and floors of multi-storey or high-rise buildings with large loads, industrial building columns and floors, etc.

The high-strength bolt transmits the stress through the friction force and is composed of three parts: bolt, nut and washer. High-strength bolt connection has the advantages of simple construction, flexible removal, high bearing capacity, good fatigue resistance and self-locking, and high safety, and has replaced riveting and partial welding in the project, and has become the main connection means in the production and installation of steel structures. For steel members made in the workshop, automatic multi-wire arc welding should be used for thick plate, and melting nozzle electroslag welding should be used for box column partition. In the field installation and construction, semi-automatic welding technology and gas shielded flux-cored wire and self-shielded flux-cored wire technology should be adopted.

Steel structure protection includes fire prevention, corrosion prevention and rust prevention, which is generally used after fireproof paint treatment without rust prevention treatment, but in the building with corrosive gas, anti-corrosion treatment is still needed. There are many kinds of domestic fire retardant coatings, such as TN series, MC-10, etc., among which MC-10 fire retardant coatings include alkyd enamel, chlorinated rubber paint, fluoro rubber paint and chlorosulfonated paint. In the construction, the appropriate coating and coating thickness should be selected according to the steel structure type, fire resistance grade requirements and environmental requirements.