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RE: Tack Welds

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Daryl:
 
Down here in the "Lower 48", engineers can sometimes be put through mind-boggling exercises to satisfy lawyers, judges, and juries.  I am preparing to state that a 1/8" diameter tack weld is basically worthless from a structural engineering perspective.  However, it sure would be nice to find something in writing to back this up!
 
Stan
 
-----Original Message-----
From: Daryl Richardson [mailto:h.d.richardson(--nospam--at)shaw.ca]
Sent: Friday, June 20, 2003 1:15 PM
To: seaint(--nospam--at)seaint.org
Subject: Re: Tack Welds

Stan,

        Do you really have to calculate this?  I (as well as a great many others on the list including yourself) can usually figure out some way to calculate just about anything; but, as you well know, the results are never any more reliable than the input data.  I suspect that the input data is really what is in question in your case.

        Perhaps you can do some special field inspections (such as ultra sound, mag particle, or X-ray).  Perhaps you can cut out and load test some of the welds to get an acceptable indication of their reliability.  Perhaps you could load test parts or all of the entire structure.  After all, you can do an awful lot of special inspecting and load testing for $4.3 million.

        Just some thoughts that you're welcome to if they are worth anything.

Regards,

H. Daryl Richardson

"Caldwell, Stan" wrote:

 It has always been my understanding that tack welds are temporary welds that should not be relied upon for the permanent connection of structural members.  In addition, since tack welds are not prequalified, their strength cannot be calculated, and must be determined through an approved (by the EOR) program of load tests on actual welds made at the jobsite at the start of construction.Nevertheless, I have recently been asked to calculate the reliable shear strength (allowable or ultimate) of 1/8 in. diameter tack welds connecting two small angles (open-web steel joist chords and bridging).  As far as I can tell, there are no provisions for this in either AWS or AISC.  I am about to conclude that these welds have no reliable strength.  Am I missing something?This is not an academic question, as it is about to become the central issue in a $4.3 million lawsuit (I am neither plaintiff nor defendant).Thanks in advance for your brilliant responses!Stan R. Caldwell, P.E.Dallas, Texas******* ****** ******* ******** ******* ******* ******* *** * Read list FAQ at: http://www.seaint.org/list_FAQ.asp * * This email was sent to you via Structural Engineers * Association of Southern California (SEAOSC) server. To * subscribe (no fee) or UnSubscribe, please go to: * * http://www.seaint.org/sealist1.asp * * Questions to seaint-ad(--nospam--at)seaint.org. Remember, any email you * send to the list is public domain and may be re-posted * without your permission. Make sure you visit our web * site at: http://www.seaint.org ******* ****** ****** ****** ******* ****** ****** ********