The main difference between light steel (cold-formed thin-walled steel) structure and ordinary steel structure is that the concept of effective section is introduced into compression member or plate. In the design of light steel compression members, when the width thickness ratio of the plate exceeds a certain value.
The bearing strength of the axial compression member should be calculated by the effective net section of the member, and the stability calculation should be calculated by the stability coefficient and effective section determined by the gross section of the member; the strength calculation of the bending (tension bending, compression bending) member should be based on the gross section to determine the tension and compression range of each plate of the member, so as to determine the effective section of the compression plate, and then carry out the strength checking calculation to ensure the stability The stability coefficient in the fixed calculation is obtained from the gross section of the member, and the deformation of the flexural member should be calculated according to the gross section.
The width thickness ratio of light steel members should be determined according to the plate support and stress state. When calculating the width thickness ratio, the width of the plate should be calculated from the edge of the section (including the corner part).
In some cases, the section is full section effective, for example, the ratio of outer diameter to wall thickness of round pipe section is not greater than 100 when Q235 is used, and not greater than 68 when Q345 is used.
Some requirements should be met when determining the hemming size, such as the maximum height thickness ratio of hemming should not be greater than 12.