The MS-NA specifies different values for the λ_LT,0 and β factors to be used in equation 6.57 of MS EN 1993-1-1 for rolled and equivalent welded sections. STAAD.Pro does not differentiate between rolled and welded sections and uses the default values in MS EN 1993-1-1 for λ_LT,0 and β. The values specified in the MS-NA are:

1. For rolled sections and hot-rolled & cold formed hollow sections:

   λ_LT,0 = 0.4 and β = 0.75

2. For welded sections:

   λ_LT,0 = 0.2 and β = 1.00

STAAD.Pro uses the buckling curves based on Table 6.5 of MS EN 1993-1-1:2005, based on different limits. This table again does not specify which buckling curve is to be used in case of welded doubly symmetric sections with h/b ≥ 3.1 and welded non-doubly symmetric sections. Hence for these cases the new implementation will still use the method specified in the base code as per clause 6.3.2.2(2).