D5.D.11.3 Clause 188.8.131.52(1) – LTB for rolled sections or equivalent welded section
The MS-NA specifies different values for the λLT,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 λLT,0 and β. The values specified in the MS-NA are:
For rolled sections and hot-rolled & cold formed hollow sections:
λLT,0 = 0.4 and β = 0.75
For welded sections:
λLT,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 184.108.40.206(2).