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Existing lintel question

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jplay2519

Structural
Oct 7, 2014
100
I have an existing CMU lintel I have to review and it seems to just be a 16" deep bond beam, you can see in the photos they have one at mid height at the rest of the walls and there are vertical applications as well to connect columns to. The steel appears to just be to finish the jamb and header. The width is 12" CMU. Am I off base with thinking that this is just a grouted/concrete beam?
 
 http://files.engineering.com/getfile.aspx?folder=06427650-11f8-45a8-99fe-da9f14a81cab&file=20160804_071044.jpg
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It could be; that would be fairly common, but it could also be a cast-in-place header on cast-in-place jambs. I can't see any mortar joints on either the jambs or the header.

BA
 
How do you plan to determine the size and location of steel reinforcement?
 
Location would just be assumed at bottom because my wall locator tool couldn't find anything (maybe due to depth of rebar into the beam from the side). Size....try to find a minimum to assume.
 
I don't know if this is an illusion but it appears to me that there is visible deflection in the lintel.
 

Gut feeling it is a pour on site concrete beam, maybe you'll neet to do some coring on the underside of the beam to determine amount of steel. Also you need a regular 4" core to determine concrete strength.


I also see the deflection, and not sure if there is a crack.

Cheers
 
I'm guessing that is a cast in place concrete beam. And I think the "deflection" was probably built that way due to deflection of the formwork. The "cracks" are also probably formwork joints, so not cracks.

Don't core drill anything. Do a bit of percussion drilling to locate and not damage the bottom bars and identify them. You can't just assume a quantity of steel. Concrete strength should not be an issue.
 
Seems like a simple metal detector ($50 variety) should be able to register some steel bars, even if not precise depth or bar size can be determined. That would concern me if you can't detect anything. If I understand you right there is a steel plate at the bottom of the beam. Maybe that is throwing off any readings but I'm curious what that is there for.
Agree with tapping around to find SOMETHING and absolutely agree you can't just assume there is steel. Wouldn't expect concrete strength to control anything as long as the visible concrete appears competent.
Curious about the deflection question. Seems like form sag could be a factor but I think I see "stair step" cracking in the block above the beam that would be consistent with beam deflection. I'd look for flexural cracking at bottom of beam midspan and maybe shear cracking (SCARY)at mid-depth of beam near the ends.

 
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