AD 460: Amendment A2 to EN 1993-1-4
In February 2021, the second amendment to the 2006 version of the stainless steel Eurocode was published, EN 1993-1-4:2006+A2:2020.
The amendment consists of one revision – Table 5.3, which lists the imperfection coefficient (α) and the plateau length (λ₀) that are used in the buckling curves for flexural, torsional and torsional-flexural buckling.
The revised table in this new amendment is presented below as Table 1.
The reason for the amendment is that since the original buckling curves were developed (more than 25 years ago), a considerable amount of additional experimental data on stainless steel compression members has been generated. The test data, supplemented by extensive numerical analyses and reliability assessments, indicate that for cold formed hollow and open sections, the existing buckling curves were too optimistic. Assessment of the data also showed that in some cases, a different buckling curve was justified for ferritic stainless steel due to its less non-linear stress-strain characteristics. Additionally, it was possible to make a distinction between rectangular and circular hollow sections, as well as lipped channels and plain channels. New data on hot finished hollow sections also enabled the addition of buckling curves for this product form. Welded box sections were conservatively assigned the same buckling curve as hot rolled and welded open sections.
Further information on the new flexural buckling curves is given in the Commentary to the Design Manual for Structural Stainless Steel, available from www.steel-stainless.org/designmanual
For torsional and torsional-flexural buckling, new test data has also suggested that the original buckling curve is too optimistic for channel section columns. In the absence of data for other open cross-sections susceptible to torsional or torsional-flexural buckling, the minor axis flexural buckling curve is recommended as a safe approximation. The same approach is used in prEN 1993-1-1:2020.
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