The Dutch NA requires the implementation of clause 12.1.1.3 and 12.1.5.3.2 of NEN 6770 and clause 12.1.1.3 of NEN 6771.
Clause 12.1.1.3 (NEN 6770)
This clause gives the equations to evaluate the effective lengths for various support conditions. STAAD.Pro uses the effective length factor "K" which allows the user to set/modify the effective lengths for a member.
Clause 12.1.5.3.2 (NEN 6770)
This clause gives methods to evaluate the buckling length of lattice sections. We do not deal with latticed section in the current version of STAAD.Pro. In any case the buckling length can be adjusted using the "K" factor.
Clause 12.1.1.3 (NEN 6771)
This clause again deals with working out the effective lengths of prismatic and non-prismatic rods. Again, the "K" factor in the current implementation of STAAD.Pro is adequate to cater for adjusting the effective lengths as necessary.
