You are correct, the "rule of thumb" is not a minimum length requirement.
As a side note, if the connection must develop the full strength of the pipe (as for some braced framed connections), the length of weld required by the HSS Connection Manual equation for shear lag fracture can be on the order of 2 or 3 times the pipe diameter . Cheng and Kulak (AISC Engineering Journal, 4th Qtr, 2000) suggest that this is overly conservative and that the stiffening effect caused by the gusset plate precludes shear lag fracture as long as the weld length is 1.3 times the pipe diameter. This could make a difference in cost and architectural impact. Any chance that AISC will reexamine this?
>>> <RainCat1(--nospam--at)aol.com> 02/14/01 10:03AM >>>
Dear Fellow Engineers,
I have a slotted hss/ gusset plate connection which is address by the AISC in
their Connections Manual for Hollow Structural Sections (specifically on
pages 6-17 through 6-29). AISC recommends "as a rule of thumb" that the
length of the weld shall be equal to or greater than the O.D. of the pipe (if
pipe is used). My interpretation is that this is a recommendation and not a
definite requirement and that a shorter length may be used provided the
numbers add up.
Also, the specification section (same book) does not require a minimum length
for the weld
Can anyone (especially from AISC) shed light on this matter?
Thanks a lot in advance!
Rainier Catubig, S.E.
San Diego, CA