Reinforcing An Existing Solid Grouted CMU Wall 1

[gte447f]

In the past, I have designed and detailed reinforcing around new openings in existing, partially grouted CMU walls. The reinforcing scheme usually involves a steel angle lintel (or 2) inserted in the mortar joint above the opening with 8" of bearing on a solid grouted cell on each end of the lintel (i.e. each side of the opening). Also, sometimes breaking out the face shells of the 1 or 2 cells on either side of the new opening and inserting vertical rebar full height, then grouting the newly reinforced cells. The second step above is meant to act as a wind column/jamb to distribute wind loads to the slab and the roof diaphragm at the bottom and top of the wall respectively.

My question is, how can alter the above reinforcing scheme if the existing wall is already grouted solid instead of only partially grouted. If grouted solid, there will not be any empty vertical cells to which to add rebar and grout. Is it possible to use the same methodology and somehow cut a vertical groove in the solid grouted wall in which to add the rebar, or is it better to bolt a piece of structural steel to the face of the wall to serve the same purpose?

 

[focuseng]

Vote: Bolt the steel. But I don't know the circumstances either so I could be wrong. Maybe other solutions too if you are going to be invasive and cut up the masonry.

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MAP

 

[OHIOMatt]

You may want to investigate carbon fiber straps that can be adhered to the wall to increase tensile strength.

 

[PEinVA]

ACI 440.7R will help you out for fiber on masonry.

http://www.concrete.org/bookstorenet/ProductDetail.aspx?ItemID=440710

RC

 

[UcfSE]

Add structural steel wind column, or brace the wall above the ceiling if possible/applicable. Create a reinforced concrete pilaster doweled to the wall. Or use FRP sheets. I wouldn't cut the solid grout and try to create a space for a bar. I can't imagine that being done well enough to work.

 

[gte447f]

Thanks for the responses everyone. I went with steel sections bolted to the face of the wall.

 

[a2mfk]

Agree with UcfSE's suggestions, though I have always been curious about carbon fiber wrap I have never used it. I don't know how many contractors in my area (Florida) there are, I know it is used a lot in seismic strengthening.

Did you design the steel in composite with the CMU or conservatively design it to carry all the loads?

 

[gte447f]

I designed the steel to carry all loads.

 

[a2mfk]

That is the way I always have done it with partially reinforced CMU, and seems to work out great in the field.

 

[TXStructural]

Glad the exterior reinforcement worked. I have seen projects where a groove was cut the length of the vertical cells and bars were inserted. You would need to solidly bed the bars with a good adhesive repair mortar, but it can be done successfully (and expensively.) Exterior steel would be significantly less expensive, if appearance and fire requirements can be met.