Source: https://www.eurocodeapplied.com/design/en1993/ipe-hea-heb-hem-design-properties
Timestamp: 2019-04-23 00:39:31+00:00

Document:
The design resistances of the profiles correspond to cross-section resistances reduced by the partial material factor γM0 in accordance with EN1993-1-1 §6.2.3(2), §6.2.4(2), §6.2.5(2), §6.2.6(2). The aforementioned design resistances do not take into account a) flexural buckling, b) lateral torsional buckling, c) interaction effects of axial force, shear force, bending moment, and d) interaction effects of biaxial bending. Therefore the presented cross-section resistances are indicative values applicable for special cases. In general the overall element resistance is smaller and must be verified according to the relevant clauses of EN1993-1-1 Section 6.
Torsional properties (IT, WT) and warping properties (Iw, Ww) are accurate results obtained from finite element analysis of the cross-section and they are reproduced from Table 1 of the following scientific paper: M.Kraus & R. Kindmann, 'St. Venants Torsion Constant of Hot Rolled Steel Profiles and Position of the Shear Centre'. The notation is described in EN1993-1-3 Annex C.
Cross-section classification for webs and flanges is presented in accordance with EN1993-1-1 Table 5.2 for the cases of pure bending without axial force and pure uniform compression without bending moment. For the case of combined bending moment and compressive axial force the section class has an intermediate value that may be equal or between the presented values.
The geometric properties that fully define the cross-section are: total height h, flange width b, web thickness tw, flange thickness tf, and root radius r. The notation is defined in EN1993-1-1 §1.7 which is reproduced in the figure above.
The basic geometric properties of the cross-section are calculated by using the fundamental relations of mechanics. The geometric quantities include the total area of the cross section A and the second moments of the area about the major axis Iy and about the minor axis Iz, where the orientation of the major axis of bending y-y and the minor axis of bending z-z is specified in EN1993-1-1 §1.7 which is reproduced in the figure above. The root fillets are taken into account in the calculated geometric properties. Due to symmetry the centroid of the cross-section (center of mass) as well as the shear center are located in the middle of the height and width.
where according to EN1993-1-1 §5.1 the value of the coefficient η is assumed equal to η = 1.2 for steel grades up to and including S460 and hw = h - 2tf is the height of the web.
The plastic section modulii Wpl,y and Wpl,z about the major axis y-y and the minor axis z-z respectively correspond to the maximum plastic bending moment when the axial force of the cross-section is zero and the stress profile is fully plastic. Due to symmetry when the full plastic bending stress profile is reached with zero axial force the section is divided into two parts separated by the axis of symmetry. The plastic section modulus corresponds to the sum of first moments of the area of the two halves about the major axis y-y and the minor axis z-z respectively.
For open thin-walled cross-sections the torsional constant IT, torsional modulus WT, warping constant Iw, and warping modulus Ww may be calculated according to the procedure described in EN1993-1-3 Annex C. The values presented in the tables for the torsional and warping properties are accurate results obtained from finite element analysis of the cross-section and they are reproduced from Table 1 of the following scientific paper: M.Kraus & R. Kindmann, 'St. Venants Torsion Constant of Hot Rolled Steel Profiles and Position of the Shear Centre'. The presented values take into account the actual thickness of the cross-section elements and the presence of the root fillets.
The design resistance of the cross-section in axial force, shear force, and bending moment are calculated in accordance with EN1993-1-1 §6.2. They correspond to the gross cross-section resistance reduced by the steel partial material safety factor for cross-section resistance γM0 that is specified in EN1993-1-1 §6.1 for buildings, or the relevant parts of EN1993 for other type of structures, and the National Annex.
The aforementioned design resistances do not take into account a) flexural buckling, b) lateral torsional buckling, c) interaction effects of axial force, shear force, bending moment, and d) interaction effects of biaxial bending. Therefore the presented cross-section resistances are indicative values applicable for special cases. In general the overall element resistance is smaller and must be verified according to the relevant clauses of EN1993-1-1 Section 6.
The elastic bending moment resistance is applicable for class 3 cross-sections. For class 4 cross-sections the effective cross-section properties must be defined that take into account the reduced effective widths of the compression parts of the cross-section as specified in EN1993-1-1 §6.2.2.5.
In general the class of the compression part is more unfavorable when it is subjected to uniform compression, as compared to pure bending. Indicative classification of the flanges and webs of the steel profiles is presented for the characteristic cases of pure uniform compression and pure bending moment. In general the class may have an intermediate value if the stress profile of the compression part occurs from a combination of compressive axial force and bending moment. The classification of the total cross-section is determined by the class of its most unfavorable compression part, web or flange.
For the classification of the webs t = tw and c = h - 2tf - 2r.
For the classification of the outstand flanges t = tf and c = b / 2 - tw /2 - r.
The appropriate buckling curve for rolled flanged sections is specified in EN1993-1-1 Table 6.2 depending on the aspect ratio h/b, the flange thickness tf, the steel yield stress fy, and the orientation of bending axis.

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