HSS Workable Flat

I have to make an attachment to an HSS4x4x1/2 and noticed in the AISC manual that the workable flat has a “-” (meaning presumably no flat). Workable flat is normally calculated as though the radiused corners have a radius of 2.25t. What’s up with the 0.5" material? Having seen a real one as part of our mockup, there is definitely a flat.


It seems they just put a ‘-’ when there is less than 2". The one exception being HSS3X1.5X1/4 shows a 1 7/8". Which is interesting because the HSS3X3X1/4 shows ‘-’.

I’ll raise you one on the peculiarity of the shapes database… How does the M4X3.45 have the exact same dimensions as the M4X3.2 ?

Above is a snippet.