Buckling curves for heavy wide flange steel columns
Keywords:buckling curves, finite element analyses, heavy wide flange section, high- strength steel, mild steel, partial factor, statistical evaluation
This paper proposes existing European buckling curves to be used for checking the resistance of heavy wide flange columns made from mild and highstrength steel, failing by flexural buckling. Buckling curves are not available in the current Eurocode3 EN 1993-1-1, for height-to-width ratios h/b > 1.2 and flange thicknesses tf > 100 mm. The buckling curves are evaluated according to the statistical procedure given in Annex D of EN 1990 using finite element analyses. Residual stress models as described in literature were used to define the initial stress state of the column in the finite element model. A large database was created containing the ratio between the elastic-plastic buckling resistance obtained from finite element analysis and the buckling resistance obtained from the proposed buckling curve for a wide set of column configurations from which a partial factor ?Rd was deduced. Different section types with flange thicknesses tf >100 mm were investigated: the stocky HD and more slender HL type, featuring h/b = 1.23 and h/b = 2.35 respectively. The materials investigated were: – Quenched and Self-Tempered (QST) steel available under the proprietary name HISTAR 460 (High Strength ArcelorMittal) with a yield stress of 460 N/mm2 ; – steel grade S460; – steel grade S355; – steel grade S235. For as far as available, statistical information on these materials was used to estimate the partial factor for material properties ?m. Then the partial (safety) factor ?M1 can be calculated as ?M1 = ?Rd · ?m. Based on the criterion that ?M1 should not exceed 1.05, buckling curves are suggested which can be used together with ?M1 = 1.0. Buckling curves to be included in Eurocode3 EN 1993-1-1 are finally proposed for heavy wide flange columns in S235 to S500, with cross-sections with height-to-width ratios h/b>1.2 and flange thicknesses tf > 100 mm. This paper is an extended and more complete version of an earlier paper
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