There are many advantages of steel structure, such as light weight, less material, low cost, short construction period, long span, safety and reliability, beautiful shape, stable structure and so on. Buildings must be solid and reliable, so the stability of steel structure is extremely important. Now let's know what the stability of steel structure is.
The stability of steel structure can be divided into two cases: the overall stability of the structure and the stability of the members themselves.
In the longitudinal direction of the structure, the overall stability of the structure is mainly guaranteed by the support system of the structure, such as the inter-column support of the steel column, the horizontal and vertical support of the upper and lower chords of the steel roof truss, etc. When calculating, the main consideration is that the bracing system can reliably transfer the vertical horizontal loads (wind load, earthquake load, crane load, etc.) of the structure. In the transverse direction of the structure, the stiffness of the structure itself (frame or bent) is mainly used to ensure that the structure itself can reliably transfer the transverse horizontal load of the structure.
The stability of the component itself is mainly guaranteed by the stiffness of the component itself. When calculating, it is necessary to ensure that the member itself and its components (members or plates) do not buckle and lose stability under load (which mainly occurs in compressive or bending members). In practical calculation, stability coefficient is usually used to limit the design strength of steel. The maximum stress in the component is not greater than the design strength of steel multiplied by the stability factor. Such formulas can be seen in the formulas for calculating the compression and bending of steel structures.
Stability coefficient is a coefficient mainly related to slenderness ratio (member) or high thickness ratio (plate). Controlling slenderness ratio and height-thickness ratio is equivalent to controlling the stability of component.
Therefore, the stability factor of the component itself is mainly the effective length and section characteristics of the component, including in-plane and out-of-plane directions. Of course, the strength and stress of the material should also be included.
