# D5.D.10.6 Clause 6.3.3(5) – Interaction factors kyy, kyz, kzy, and kzz

The NBN-NA recommends the equations in Annex A of NBN-EN 1993-1-1 to calculate these interaction factors.

The NA also mentions that torsional flexural buckling needs to be taken into account in case of mono symmetric sections. Torsional flexural buckling will need to be taken into account based on the method given in the NCCI document "SN001a-EN-EU: Critical axial load for torsional and flexural torsional buckling modes". See section below for details.

The NA also recommends a lower limit as given below for the term Cmi,0 in table A.2 of Annex A:

$C m i , 0 ≥ 1 − N E d N c r , i$