Calculation of slenderness

The slenderness (slenderness ratio) is calculated according to clause 5.8.3.2(1) in EN 1992-1-1.

λy(z) = l0,y(z) / ic,y(z)

where

l0,y(z) is the effective length of the member (column) around y(z) axis of LCS (perpendicular to y (z) axis of LCS), which can be defined via Buckling data, see "Calculation of slenderness"
ic,y(z) is the radius of gyration of the uncracked concrete section in direction of y (z) axis of LCS

The simplified values and formulas for calculation of effective length for isolated columns, braced and unbraced frames are described in clauses 5.8.3.2(2-4) in EN 1992-1-1

The slenderness is calculated in each section, it follows that for arbitrary member and member with haunch, the slenderness can be different along length of the member