Re: design of butt weld

Oops, I just re-read your post.  The factor of 0.3xfu (weld) posted by
someone else is applied along the area of the weld throat for fillet welds
for AISC standards (assuming that the base metal is checked for sufficient
strength along the weld, also).  AASHTO standards (10.32.2) used to have a
slightly reduced factor of 0.27 to allow for more safety.

But as you are asking about butt welds, not fillet welds, both AISC and
AASHTO appear to allow a weld strength equivalent to the allowable
strength of the base metal, unless you are joining two dissimilar metals
in which case you should use the lesser allowable strength of the two
metals.

All the above assumes that you are using steel in accordance with AISC
and/or AASHTO specifications, not some exotic or unusual alloy that has
different welding requirements.  You should really check your prevailing
specifications depending on the type of service you are welding for, such
as railway (AREA), highway (AASHTO), etc., and as well as the steel/metal
alloy you are welding.  Careful adherence to prevailing specifications
becomes an issue of liability in the event of weld failure, especially if
you are designing fracture-critical members.

Bob


On Tue, 25 Nov 2003, hoho wrote:

> how much then is the factor for fatigue loading?