The level of axial load at which a section becomes Class 2 is not required because the same section properties (the gross area and plastic modulus) are used in the resistance calculations for both Class 1 and Class 2 sections.Ĭlass 4 cross sections are not considered in this article. SCI P363 gives axial load ratios where (under increasing levels of axial load) a section becomes Class 3 and Class 4. Section classification is also given in resistance tables, such as SCI P363 (the ' Blue Book' ). The class of the cross section is determined from Table 5.2 of BS EN, where a cross section is classified according to the highest (least favourable) class of its parts subject to compression. Class 4 cross-sections are those in which local buckling will occur before the attainment of yield stress in one or more parts of the cross-section.Class 3 cross-sections are those in which the stress in the extreme compression fibre of the steel member assuming an elastic distribution of stresses can reach the yield strength, but local buckling prevents development of the plastic moment resistance.Class 2 cross-sections are those which can develop their plastic moment resistance, but which have limited rotation capacity because of local buckling.
4.3 Uniform members in bending and axial compression.4.2.2 Reduction factor for lateral torsional buckling of rolled sections.4.2.1 Lateral torsional buckling resistance.
0 kommentar(er)
