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Re: CJP Weld in a Moment Frame

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Chris,

Good point about the fillets not being as stiff as the CJP.  I don't think shear lag in the flange will be too bad because there isn't a big moment gradient.  i.e the moment is large but it is doesn't change a lot over a short distance, so not much shear in the web and not much shear lag.

I think you would buy something like AISC Design Guide #4 on page 40 which shows fillets top and bottom of the flanges.  So, no difference in weld stiffness because all the welds are fillets.  the procedure there used yield-line theory to evaluate bending in the end plate but doesn't address through-plate shear.  If I use all fillets, I would just have to bump the size by 50/36 or change the plate to 50ksi material.

MJ



--- On Fri, 2/26/10, Christopher Wright <chrisw(--nospam--at)skypoint.com> wrote:

> From: Christopher Wright <chrisw(--nospam--at)skypoint.com>
> Subject: Re: CJP Weld in a Moment Frame
> To: seaint(--nospam--at)seaint.org
> Date: Friday, February 26, 2010, 1:04 PM
> 
> On Feb 26, 2010, at 1:40 PM, Mark Johnson wrote:
> 
> > Thank you for your answer.  You write: "but if
> you're trying to spreading the flange force over a larger
> area by adding a fillet, I don't think that's going
> happen."
> > 
> > That is exactly what I'm trying to do.  How can
> that not work?
> The load spreads according to local stiffness. The fillets
> aren't as stiff as the butt weld and they won't carry as
> much load. Because the fillet welds are soft (structurally)
> they deform without picking up much load. In effect the load
> doesn't 'spread' uniformly. Moreover, shear lag makes for a
> non-uniform load distribution in the beam flange--much more
> load is carried near the beam web than out near the ends so
> the distribution isn't uniform to begin with. I'm not real
> sure how I'd do this in this case, but I'd probably start by
> trying to understand from the actual application how the
> loading actually carries from the pure bending distribution
> in the beam to a through-thickness shear in the plate. Some
> of the connection details shown in Blodgett may help.
> 
> Christopher Wright P.E. |"They couldn't hit an elephant at
> chrisw(--nospam--at)skypoint.com   |
> this distance" (last words of Gen.
> .......................................| John Sedgwick,
> Spotsylvania 1864)
> http://www.skypoint.com/members/chrisw/
> 
> 
> 
> 
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