Wedge plate design/failures

[OUOY]

Hi everyone,

Recently we've had quite a few wedge plates failing when testing our tiebacks (both 25/35 deg). It seems like they're failing due to lateral loading, we're thinking either the piles are misaligned or the tiebacks weren't drilled straight back causing some unintended loading.

We haven't really had this happen in such excess in the past ~10 years of shoring so I've been looking into redesigning them and a little stuck on a straight forward way of analyzing them without just adding small plates to the sides to prevent sideways movement.

We use 3/8" plates currently and I don't really think upping the thickness is going to prevent the movement.

I'd rather not have them weld our walers to them and have to deal with that when removing them after detensioning as well.

Not sure if anyone has any suggestions on how to go about this but anything is pretty helpful.

 

[PEinc]

For angled, welded, seats for tieback wales, I try to use a piece cut from an HP or WF section with a minimum web thickness of 1/2 inch, sometimes 7/16 inch. The piece's flange and web get welded to the soldier beam. The web is usually strong enough to prevent its failure and the welded flange prevents lateral failure. The tieback seat should be a short as possible, keeping the waler as close as possible to the soldier beam. If you are talking about tieback angle seats for thru-beam connections without walers (one tieback through each soldier beam), what you need to do depends on the type of soldier beam you are using. You might use a pair of parallel, triangular plates welded to the soldier beam or a horizontal, heavy, steel angle with each leg welded to the soldier beam's front flange.

http://www.PeirceEngineering.com

 

[PEinc]

http://www.PeirceEngineering.com

 

[OUOY]

Thanks for the response a bit ago, sorry kinda forgot about this post.

Those look pretty strong! We're going to be trying out thicker plates for our next project as for some reason my boss/field guys don't want to chop up the beams (even though we have tons and tons of scrap piling..)

If that doesn't go as planned, I'll probably suggest we send a welder down to our yard when they have downtime and cut these up prior to projects.

 

[PEinc]

Frequently the buying lengths of the soldier beams are long enough to allow for a piece to be cut off for the tieback bracket - as long as the web is about 0.5 inches thick.

Your photo makes it look like you have the thin edge of the waler bracket bearing against a thin edge of the waler (i.e., two thin members bearing against each other in a perpendicularly crossing direction. Possibly not enough bearing area so that one or both thin members cripple?

http://www.PeirceEngineering.com

 

[EngMan40]

OUOY: Listen to PEinc, he knows a lot about sheeting & shoring, and underpinning.