Effective Section properties

The design of a section that does not satisfies table 5 of SIA 263 is always performed by using a reduced area. This classification corresponds to the EER method. The determination of a reduced area is based on the effective width of each compression element in the current section (Art. 4.5.3). The using of a reduced area implies the recalculation of the shear centre position, the inertia and the elastic modulus.

For a detailed overview of the effective section calculation reference is made to "Effective Shape".

The Cross-section requires an Initial Shape in order to calculate the Effective Shape and Effective Properties.

A_eff is the effective area of the cross section when subject to uniform compression.

W_eff is the effective section modulus of the cross-section when subject only to a moment about the relevant axis.

e_N is the shift of the relevant centroidal axis when the cross section is subject to uniform compression.

Additional moments ΔM_Ed due to the possible shift e_N of the centroid of the effective area A_eff are accounted for according to EN 1993-1-1 art. 6.2.2.5(4). These additional moments are neglected in case they would have a favourable effect on the check result.

CHS members with Class 4 cross-sections are checked as elastic, Class 3.