The classification of cross-sections according to EN 1993-1-1 using Table 5.2 is a simple method for designing the local buckling of cross-section parts. For cross-sections of cross-section class 4, it is then necessary to determine the effective cross-section properties according to EN 1993-1-5 in order to consider the influence of local buckling in the ultimate limit state designs.
Utilize the RF-/STEEL Cold-Formed Sections module extension to perform ultimate limit state designs of cold-formed sections according to EN 1993-1-3 and EN 1993-1-5. In addition to the cold-formed cross-sections from the cross-section database, you can design general cross-sections from SHAPE-THIN.
In SHAPE-THIN, the calculation of stiffened buckling panels can be performed according to Section 4.5 of EN 1993-1-5. For stiffened buckling panels, the effective surfaces due to local buckling of the single panels in the plate and in the stiffeners, as well as the effective surfaces from the entire panel buckling of the stiffened entire panel, have to be considered.
The buckling analysis of plates with stiffeners is a special task for engineers. For this, EN 1993-1-5 provides three calculation methods: Effective Cross-Section Method, [1], Sect. 4-7; Reduced Stress Method, [1], Sect. 10; Finite Element Methods of Analysis (FEM), [1], Annex C.
Torsional buckling analysis of transverse and longitudinal stiffeners with open cross-sections is described in DIN EN 1993-1-5, Chapter 9. There is a difference between the simplified method and the precise method, which takes into consideration the warping stiffness of the buckling panel. The simplified method applies Equation 9.3 of DIN EN 1993‑1‑5. If warping stiffness is to be taken into account, either Eq. 9.3 or Eq. 9.4 should be followed. Both design methods are implemented in PLATE-BUCKLING.
In January 2015, DIN Committee NA 005‑08‑23 Steel Bridges applied the introduction of a modification in equation 10.5 of DIN EN 1993‑1‑5. This involves the interaction of longitudinal and transverse pressure in a buckling analysis. Now, the interaction equation provides for auxiliary factor V, which is calculated from the reduction factors of the longitudinal and transverse stresses.