steel structure: it is composed of steel plate, section steel, cold-formed thin-walled section steel and other structures connected by welding or bolts.

Features of steel structure: light weight and high strength; good plasticity and toughness; isotropy, stable performance; weldability; not easy to leak; heat resistance but not fire resistance; poor corrosion resistance; simple manufacturing, short construction period.

    Plasticity: the ability of a material to absorb deformation energy under static load.Good plasticity will prevent the structure from breaking suddenly due to accidental overload in general, and provide safety guarantee for people.

    The purpose of structural design is to ensure that the designed structure and structural components can meet various predetermined functional requirements and have appropriate reliability in the process of construction and work.

    Note the steel members, I will talk about what is the support and what is the inclined bearing when calculating the quantity. Ha ha steel structure usually has frame, plane truss, grid (shell), cable membrane, light steel, tower and mast and other structural forms.

    Its theory and technology are mostly mature.There are also some problems that have not been solved, or there is no simple and practical design method, such as the stability of latticed shell.

    The characteristics of different structural forms should be considered in the selection of structures.In the industrial workshop, when there is a large hanging load or a large range of moving load, it can be considered to abandon the portal frame and adopt the grid frame.In the area with high basic snow pressure, the roof curve shall be conducive to snow sliding (snow load is not required to be considered beyond the tangent line of 50 degrees). For example, the limestone warehouse shed of cement plant adopts three center circular mesh shell, and the total snow load is released nearly half compared with the sloping roof.Similar consideration for areas with large rainfall.When the building allows, the arrangement of supports in the frame will be more economical than the simple frame with rigid joints.In the buildings with large roof span, the suspension or cable membrane structure system can be selected.In the design of high-rise steel structure, steel-concrete composite structure is often used. In high-rise buildings with high seismic intensity or very irregular, the form of core tube plus outer frame should not be selected simply for the sake of economy.The surrounding giant SRC columns should be selected, and the core is the structural system of supporting frame.More than half of these high-rise buildings in China are the former, which is not good for earthquake resistance.

    The layout of the structure should be considered comprehensively according to the system characteristics, load distribution and properties. Generally speaking, the rigidity should be uniform, the mechanical model should be clear, and the influence range of large load or moving load should be limited as much as possible,It should be transmitted to the foundation by direct line. The distribution of anti side bracing between columns should be uniform. Its centroid should be close to the action line of lateral force (wind, earthquake) as far as possible. Otherwise, the torsion of the structure should be considered. The anti side of the structure should have multiple lines of defense. For example, if there is a supporting frame structure, the column should be able to bear at least 1 / 4 of the total horizontal force alone

   Sometimes, the load transfer direction can be adjusted to meet different requirements for the layout of the secondary beams in the floor plan of the frame structure.Generally, in order to reduce the cross-section, the secondary beam is arranged along the short direction, but this will increase the cross-section of the main beam, reduce the floor clear height, and sometimes the top side column will not be able to bear it. At this time, supporting the secondary beam on the shorter main beam can sacrifice the secondary beam to keep the main beam and the column