Tying a Concrete Facing to an Existing Bin Wall

[3Fan]

Hi, we are working on putting together a bid for a Design/Build project where we are to rehabilitate an existing bin wall by "tying" new rebar to the existing wall and then placing a cast in place 8" wall facing on the front of it. The spill thru slopes in front of the pile supported abutments were pulled back to allow another lane of traffic to pass under the bridge 20 years or so after it was originally built. They used a light gage crib wall to support the embankment. By light gage I mean the stringer gages are 12 at the bottom and 16 at the top. The wall is about 18.67' tall. As in most design/build scopes, it is mainly left up to the contractor to come up with a solution. The only guidance like I mentioned above. Face the existing wall with 4000 psi concrete. Provide reinforcing steel and tie the steel to the face of the existing bin wall. Minimum wall thickness of 8".

Anyone have any good ideas on how to tie rebar to the existing light gage bin stringers?

Thanks,
Greg

 

[PEinc]

If the existing bin wall is not in excellent condition, i.e. if it has, or if you suspect, visible damage or corrosion, then I would not count on any structural contribution from the existing bin. Instead, I would design a replacement retaining wall. I did this for two Connecticut DOT design-build projects when I worked for Schnabel Foundation Company. We obtained a patent for a metal bin wall repair/replacement. Your wall is fairly high and, if you have limited area for a new gravity wall, you will probably need tieback anchors or possibly soil nails. See U.S. Patent No. 4,911,582 for the repair or improvement of retaining walls using post tensioned tieback anchors.

http://www.PeirceEngineering.com

 

[3Fan]

Thanks for the help! Nice article. I don't think it is the owners intent to place a new structural wall in front but more to protect the wall from the elements. But the scope is pretty vague.

How thick are the vertical connectors in a bin wall? I assume these are more of a bent plate element as opposed to a rolled light gage product? Could a nut be welded onto the vertical connector? Or could you even weld a headed stud onto the vertical elements?

 

[PEinc]

I don't know what type of bin wall you have, but those I am familiar with are light gauge, rolled steel. They get their strength from the deep corrugated shape of the front and back horizontal panels. I would think that the sheet metal is too thin for welding nuts or studs. Search for ARMCO or Contech metal bin walls.

http://www.PeirceEngineering.com

 

[PEinc]

http://www.conteches.com/products/retaining-walls/metal/bin-wall.aspx

Click on the Bin Wall Brochure link.

http://www.PeirceEngineering.com

 

[3Fan]

I agree with your thoughts. But I spoke with our local CONTECH rep. He said the vertical connectors are bent plates that are typically 5/8" thick. I guess I need to go find a bin wall and measure some thicknesses.

 

[PEinc]

Be careful. If the bin wall is in good shape, why do they need to rehabilitate it? How old is the wall? It may not be a Contech wall.

http://www.PeirceEngineering.com