Brief introduction to the structural system of steel structure
1. the basic form of the project: generally reinforced concrete column foundation or raft foundation. When there is a basement, the steel column can extend directly to the basement, and the transmission path of the structure is simple and convenient; the structure construction cycle is short, and the comprehensive cost is reduced.
2. Steel frame or frame bracing system 1) braced steel frame or frame: mainly uses the steel tube concrete column, H light beam frame system and H type T shape steel frame system composed of connecting steel column and H beam prefabricated light steel frame beam through field assembly of two kinds of steel structure and two the direction of multi frame system types in the steel structure system of steel structure residence. Steel frame concrete filled steel tubular column, which is composite high strength concrete compression member filling in empty steel tube is formed, it uses steel tube confined concrete, the steel tube concrete in compression to three, thus improving the concrete compressive strength and ductility of the concrete pipe, at the same time, to ensure the local stability of steel pipe, therefore combining the advantages of concrete filled steel tubular column steel column and concrete column, greatly improve the axial bearing capacity of single column, columns significantly reduced, compared with the H type steel column, can save the steel quantity about 50%, reduce the cost of about 45%, the diameter of the pipe wall thickness change, gradually thinning; in addition, concrete filled steel tube concrete column the temperature can absorb heat, slow down the speed of steel column, and once the steel column yield, concrete can withstand axial load most, to prevent collapse of structure. Composite frame type H steel T shaped connecting steel column, steel structure is using prefabricated steel frame plate (steel columns, steel beams and supporting frame combination), combination of field, technology is more advanced, at the corner of the two phase H column with vertical font processing method, two are strong stiffness, no weak axis; increase the lateral stiffness (with some support), the overall structure of the force effect is good. Each single frame can be wall keel, door and window frame at the same time, through on-site assembly, high strength bolt and the connecting plate is connected with the frame, so that the scene can be directly to the frame and the wall material and the doors and windows together in place, accelerate the construction speed.Steel frame beam was used for high frequency welding of H steel, its advantage is that the flange width and thickness can be changed arbitrarily according to the requirements of the design, the thickness of the web plate can meet the H type steel bizar local stability conditions (the I-beam) thin section from the inertial bizar H type steel to increase 20~30%, to withstand the bending moment of frame beam mainly is saved 20~30% steel, therefore, in comparison with the rolled H steel because of the advantages of light weight, high strength, beautiful appearance, convenient processing, according to the design requirements at length, strong production capacity and make it more economical and reasonable and the section sizes of flexible characteristics. Between the steel column and steel beams connected with rigid connection and articulated two forms, rigid connection refers to the web connected by high strength bolts, flange welding connection form; hinged connection refers to the web connected by high strength bolts, the upper and lower flange connection without welding. The former requires site welding, the latter without welding, installation is not affected by weather and seasonal restrictions, therefore, to simplify the installation process, the amount of field operations is greatly reduced and the speed of installation of steel structure can improve. At the same time the use of the hinge node, in the calculation of beam design, all calculated using steel concrete beams, steel beam tension, cast-in-place concrete compression, make full use of two kinds of steel and concrete material mechanical characteristics, can save steel consumption of steel, but also lowered the beam height increased the use of space. 2) the horizontal force structure of the steel structure, the slab and the roof board, is divided into two types: Prefabricated floorslab and cast-in-place floorslab. As a result of seismic, easy to crack, sound insulation effect and other factors, rarely used. The present stage adopts cast-in-situ concrete floor, it is divided into profiled steel concrete (composite) cast-in-place concrete and ordinary template two forms, the latter from the economic point of view is more characteristic of the former is more suitable for the steel structure of steel plate is used as template and replace the floor stress below the bar; meet the fire safety requirements; the need to provide engineering support mold; working face, to facilitate the construction and equipment of cross operation; does not affect the construction period; the ceiling is neat, without mortar (falling objects wounding), to two times the decoration effect (paint, wallpaper or other shows).
3. the selection of the retaining wall material which adapts to the steel structure system is a very important factor to restrict the development of the steel structure housing. It requires the high degree of factory, connected with the steel structure is easy, the light weight and high strength, the waterproof, anti permeability and frost resistance, the thermal insulation, energy saving, the exterior finishes, the refractory, and durability, easy to accept the economic indicators, etc.. China's reform of wall has been for many years, but because the residential wall is affected by various factors, especially in the northern region, the thermal insulation waterproof performance, safety performance and economic index is high, although various materials (composite wall) a lot, but few people can really be accepted. Therefore, many developers have to use the hollow brick block most traditional form, the use of lightweight aerated concrete block local production (density 700kg/m3), but there is always different from the characteristics of the steel structure housing; the composite wall has many forms, such as: ALC, the light wallboard; concrete plate with benzene plate; and benzene plate block DP film; network, with the panels can also ensure that the function of the wall mortar. With the development and perfection of building materials industry in our country, the wall materials suitable for the production of steel structure houses will be springing up in large numbers.
4. the steel structure of the fire in the current specification to meet the fire safety requirements, fire protection of steel structure generally adopts thick coating and thin coating (expansion) two, in fact, the choice of steel structure fireproof materials accounted for a large proportion of the cost of the whole steel structure, which also hindered the steel structure housing smoothly. In the design of steel structure fire protection, we can still adopt flame retardant wallboard and building block (Bao Fu) to carry on the fire prevention method of steel structure. For example, a fire-resistant rock wool board is arranged in the fireproof board and is fixed on the steel member through the fastening piece. This method is not only limited by the weather conditions, but also integrated with fire protection and decoration.
5. The corrosion of steel structure and the corrosion of steel structure are closely related to the relative humidity of air and the content of corrosive substance in the atmosphere. Usually the relative humidity is below 60%~70%, the atmospheric corrosion of steel is slight, and once the critical humidity (60%~70%) exceeds the corrosion of steel, the corrosion rate of steel will be accelerated. Therefore, it is necessary to brush or spray anticorrosive coatings on the surface of the steel structure. Fire retardant paint (primer and topcoat), the primer should be good adhesion to the steel surface, paint and primer of strong adhesion, paint between the role, performance and hardness matching. Most solvent based inorganic zinc rich primers are used. Because of this kind of anti rust primer and long service life, but also resistant to high temperature 5000C. In the choice of materials selection of steel structure and fire prevention, anti-corrosion materials, Baosteel has developed weathering fire-resistant steel, and passed the fire test, if the application of weathering refractory steel in the steel structure housing, will significantly reduce the cost of fire prevention measures for corrosion protection of steel structures.
6. the construction of steel structure as the frame node, in the design of steel structure component standardization, namely each column with three layers of H steel beam and corbel node design into a number of standard components, achieved a production factory, such as assembly of steel structure construction laid the foundation. Therefore, the steel structure installation can be single column installation, a hanging three beams in place connection; at the same time can also be factory safety frame mesh, on-site overall lifting construction method. For concrete filled steel tubular columns, the concrete can be divided into three sections and divided into four sections.