D5.D.13.7 Clause 220.127.116.11 - Slenderness for torsional and torsional-flexural buckling
Equations 6.52 and 6.53 of BFS EN 1993-1-1:2005 are to be used to calculate the non-dimensional slenderness λT, to be used for torsional and torsional-flexural buckling checks. BFS EN 1993-1-1:2005 does not provide equations to calculate the elastic critical loads Ncr,T,F and Ncr,T (refer 6.3.14 of BFS EN 1993-1-1:2005).
The NCCI document SN001a-EN-EU: Critical axial load for torsional and flexural torsional buckling modes provides methods to calculate the Ncr,TF and Ncr,T factors and therefore these methods are used to evaluate the elastic critical loads for the SW-NA.
The critical axial load for torsional buckling is evaluated as:
The critical axial load for torsional-flexural buckling is evaluated as:
For details on these equations, refer to the NCCI document SN001a-EN-EU.