Section properties

3.1 Classification

Flanges and webs have been classified in accordance with Table 5.2 of EN 1993-1-1. The dimensions of the flange outstand and web depth have been calculated neglecting any weld.

The variable ε has been based on the design strength, not the nominal strength.

3.2 Second moment of area

The second moment of area has been accurately calculated and rounded to three significant figures. Any welds have been neglected in the calculation.

According to EN 1993-1-5 clause 3.1(2) the effect of shear lag must be considered at SLS. Therefore, if there is a reduction in effective area due to shear lag, this has been recognised in the calculation of the second moment of area. The effect of shear lag in plate girders without longitudinal stiffeners increases as the span of the member decreases. The tables therefore present the second moment of area calculated for the shortest tabulated span.

3.3 Effective section properties

For Class 1, 2 and 3 sections, the design strength of the web, f_yw is limited to that of the flange, f_yf.

For Class 4 sections, shear lag (both flanges) and plate buckling (compression flange only) are considered, in accordance with EN 1993-1-5 clause 4.3(1). A reduced effective area of the flange is calculated if necessary to account for shear lag and plate buckling.

For the webs of Class 4 sections, clause 4.4(3) of EN 1993-1-5 requires that the stress ratio ψ is based on the effective area of the compression flange and the gross area of the web.

For Class 4 webs, an effective area of the compression zone is calculated in accordance with clause 4.4(3). For hybrid members, the design strength of the flange is used to calculate the slenderness, in accordance with clause 4.3(6) of EN1991-1-5:2006.