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# RE: CJP Weld in a Moment Frame

• To: "seaint(--nospam--at)seaint.org" <seaint(--nospam--at)seaint.org>
• Subject: RE: CJP Weld in a Moment Frame
• From: Richard Calvert <RichardC(--nospam--at)lbbe.com>
• Date: Fri, 26 Feb 2010 10:22:51 -0500
• Accept-language: en-US
• Acceptlanguage: en-US

```Mark,

The AISC only prescribes the weld of the flanges as moment resisting (the web's weld does not count)

The formula for E70xx, in ASD, would be 0.928*b_f*t_f*16 > Mmax /(d - 2*t_f)

Where Mmax, in your case, would be the maximum allowable bending of the member, as apposed to the required strength.

this wont work - in which case add the additional number of 16ths of an inch worth of fillet thickness to the value of t_f*16 on the left side of the above equation.  (i.e. 1/4" fillet is (4) 16ths, so the left side of the formula becomes 0.928*b_f*(t_f*16 + 4)

but on a side note, unless the beam end was designed to realize 95-100% of its bending capacity, then you're worries may be a bit overly conservative.  And if it is that stressed, you may want to look into RBS joints ilo beefy welds

good luck

-----Original Message-----
From: Mark Johnson [mailto:markajohn(--nospam--at)yahoo.com]
Sent: Thursday, February 25, 2010 6:33 PM
To: seaint(--nospam--at)seaint.org
Subject: CJP Weld in a Moment Frame

List,

I have an application where I wanted to weld a 50ksi wide flange to the face of a 1.25" thick 36 ksi plate and fully develop the 50 ksi wide flange.  (it's part of an ordinary moment frame)  I think it would be better to use fillets, but since it's not my call, I believe it will be done with a CJP.  I want to be able to show my client that he should add a fillet to the CJP, or else the 50 ksi plate won't be fully developed and that the weak link will be the interface between the weld and the 36ksi plate.  Also, this would produce a sudden brittle failure, not a good thing in earthquake country.

I would like to find an example calculation or an opinion on this.

TIA
MJ

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