Simplified criterion for second order effects of isolated members: the slenderness λlim
Eurocode 2 part 1-1: Design of concrete structures 5.8.3.1 (1)
Second order effects may be ignored if the slenderness (λ = l0/i) is below a certain value λlim.
Recommendation
The recommended value for the slenderness λlim follows from:
λlim = 20⋅A⋅B⋅C / √n | (5.13N) |