BUCKLING CURVES FOR HEAVY WIDE FLANGE STEEL COLUMNS · wide flange sections, i.e. wide flange sections with flanges thicker than 40 mm. At ... beams in short- or medium-span bridges
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BUCKLING CURVES FOR HEAVY WIDE FLANGE STEEL COLUMNS H. H. SNIJDER 1 , L.-G. CAJOT 2† , N. POPA 2 , R. C. SPOORENBERG 3 Abstract. This paper proposes existing European buckling curves to be used for checking the resistance of heavy wide flange columns made from mild and high- strength 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 t f > 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 γ Rd was deduced. Different section types with flange thicknesses t f >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/mm 2 ; – 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 γ m. Then the partial (safety) factor γ M1 can be calculated as γ M1 = γ Rd · γ m . Based on the criterion that γ M1 should not exceed 1.05, buckling curves are suggested which can be used together with γ 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 t f > 100 mm. This paper is an extended and more complete version of an earlier paper [1]. Key words: buckling curves, finite element analyses, heavy wide flange sections, high- strength steel, mild steel, partial factor, statistical evaluation. 1. INTRODUCTION The advent of Quenched and Self-Tempered (QST) steel sections which combine high strength (i.e. nominal yield stress greater than 430 N/mm 2 ) with good ductility and weldability has led to a broadening of the possibilities in steel 1 Eindhoven University of Technology, Department of the Built Environment, P.O. Box 513, 5600 MB Eindhoven, The Netherlands 2 ArcelorMittal, Long Products, 66, rue de Luxembourg, L-4009 Esch/Alzette, Luxembourg 3 Iv-Consult b.v., P.O. Box 1155, 3350 CD Papendrecht, The Netherlands
