The D-NA introduces a new clause 6.3.0, which in turns requires the checks as per clauses 12.1.2.2, 12.13.2 and 12.1.4.2 of NEN 6771 to be applied.
Clause 12.1.2.2 (NEN 6771)
This clause in NEN 6771 determines the relative torsional slenderness and is
given as:
where
Nc;u;d | = | A×fy;d |
A | = | area of section |
fy;d | = | the yield stress |
FE;θ
| = | the Euler-torsion formula |
This value of slenderness is to be used to calculate the modification
factors used in section 6.3 of EC-3.
Clause 12.1.3.2 (NEN 6771)
This clause works out the relative torsional-flexural buckling slenderness
for compression members. The relative torsional-flexural buckling slenderness is given
as:
where
Nc;u;d | = | A×fy;d |
A | = | area of section |
fy;d | = | the yield stress |
FE;tk | = | the Euler torsional buckling strength |
Clause 12.1.4.2 (NEN 6771)
Buckling lengths of rotationally restrained bars with intermediate spring supports.
Note: STAAD.Pro does not allow for these end conditions, specifically. The effective length factors may be used to accommodate this requirement.