How much steel in concrete? 2

[MikeVV]

I have a client that wants to put a doorway in a load bearing wall. The wall, 18 inch thick concrete, engineered and built in 1963, has reinforcing steel but I do not know how much. <br>
<br>
I could make the opening and use the steel to meet requirements but I do not know how to identify it without breaking the wall header apart. Are there any good techniques for 1) finding the old engineering drawings, and 2) measuring the existing steel content of this wall?<br>
<br>

 

[merbas]

use ultra sonic test to clarify the please and thicness of metal reinforcement

 

[faf]

How big is the opening is the first question? If it's a man door, around three feet wide, probably don't care what the reinforcing is. Plan concetre will span over the opening. If it's wider, say an overhead door, any reinforcing in the wall won't be in the right place to act as a lintel or header. You would add structural steel. The best way is to add a steel channel on either side and bolt through the wall to connect the two channels. Do this before the concrete is cut out. Extend the channels beyond the opening and use the concrete on either side as a concrete column, or add steel jambs. After the concrete is removed, weld a plate across the bottom of the two channels to finish the opening, close off the ragged edge of the concrete and add to the support provided by the bolts. Don't bother trying to find out what steel is in the wall. You can find that out when you knock out the concrete but then, who cares. It woun't do you any good anyway.

 

[MikeVV]

faf,<br>
<br>
The opening will be 10' wide x 7' tall. I plan to add steel for the header unless a way of using existing reinforcement can be justified. I also plan to add steel jambs on one side and use the concrete wall on the other for "column" support. <br>
<br>
I've reached the same conclusion regarding further research into the existing design - my local building permit research has come up with no data. I contacted the son of the original architect (the original architect is 80+ years old now) but they have destroyed their drawings (the work was done in 1963)...<br>

 

[MPHenry]

MIKE VV<br>
I have used the procedure outlined by FAF on several occasions both with reinforced concrete walls and masonry walls. In the case of masonry, the channels can be supported at both ends, on each side of the wall, with acrow props or similar as a temporary measure.<br>
If you do not wish to have the channels remain, then they can be used as temporary supports and a new steel frame of adequate design inserted into the opening in the concrete wall. Any gap between the frame and opening can be grout filled with a non-shrink epoxy grout. The channels can now be removed and the bolt holes in the concrete patched.<br>
Regards<br>
Mike

 

[merbas]

non shrink epoxy you can use epolith 2092 from

http://www.pieri.com

it is really good.

 

[MikeVV]

Thank you for posting to this message - I will use the internal steel frame and grout to minimize sag after installation.