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Re: Drag Connections to Concrete Tilt-up

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Joe,

Are those forces already multiplied by Omega for collector design already? If not, your diaphragm might not be able to transfer that load into the WF unless you have concrete fill o/ the metal deck.

Dave is correct in the futility of trying to get that into a thin panel.

A couple of things I've done in the past, but it requires a thicker wall (at least at the top)....

- Cast a steel beam full length with the panel at the top with 2 rows of nelson studs on the bottom flange.  You can thin it out a bit once you get below the WF to a thickness that works for your shear... I would recomend at least 3" of cover to the sides of the flange tips and 24" below the bottom of the WF (Or jjust make the whole wall thicker). Have the ends of the beam stick out/cantilever a foot or so. Then use a shear tab with 2 rows of bolts to connect your WF beam to the embedded WF beam. Use 1 row to carry the gravity load and the other row to transfer the collector force. If the two rows of bolts is not enough to transfer the force, then field weld the top flanges together to make a full pen weld and neglect the bolts for transfer of force, If that's still not enough, then also weld the bottom flanges CJP. Welding the flanges allows you to use the flange area  (0.9 x Tf x Bf x Fy ) to transfer the force. The force is then dissipated in the tilt panel by shear transfer from the headed studs. This way is the cleanest and easiest to build in my opinion.

- Another way is to cap the shearwall with a channel and headed studs, then let the WF beam run over the top and stitch weld the bottom flange to the back side of the web of the channel. You will also need alot of chord steel on either side of the headed studs to develop the force out of the wall. This might work if your force level is already at omega level.

- The drag bar idea with a steel bracket is feasible with an end plate, but it's a b!tch to install, never seems to get done right during placement and doesn't give you a lot of tolerance. You need a very thick plate and big huge A706 bars welded to the back of the plate. You need to splice them to bars inside the panel using groove welds and angle splice or couplers.

anyway, hope this might help.

-g

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On Thu, Feb 12, 2009 at 3:53 PM, Joe Goldbronn <jgoldbronn(--nospam--at)barrish.com> wrote:

I was looking for a good source, website or book, for higher end drag connections to concrete tilt-ups.  The forces I have are in the range of 200k-300k and is to be attached with a wide flange at the ends of the panel.  Any help would be appreciated.

 

 

Joe Goldbronn