Cracked CMU @ Point Load

[IsaacStructural]

Please see the image attached.

I wasn't on site but was passed along this image of cracking in a CMU wall on one of our jobs. Seems fairly clear that the cracking is the result of the point load from the beam. My guy on site didn't think there was any foundation issue (though he isn't structural).

As of yet I don't have the necessary information to do a full investigation of the loading on the beam, but as a general approach, I'm thinking of shoring the beam and having a solid masonry bearing pocket built under the beam (or possibly using a W8 bearing beam) to distribute the load and then just verifying the adjacent lintels for the loading, etc. to get the load down to the foundation.

How easy is it for the a contractor to rebuild the wall in service like that, and will the expansion of the grout be enough to get a positive bearing under the beam before the temporary shoring is removed? Any other thoughts, concerns?

Thanks.

M.S. Structural Engineering
Licensed Structural Engineer and Licensed Professional Engineer (Illinois)

 

[IsaacStructural]

Oops I don't think I did the image upload properly. See if the link below works.

Thank you.

M.S. Structural Engineering
Licensed Structural Engineer and Licensed Professional Engineer (Illinois)

 

[msquared48]

Better get a structural engineer out there to take a hard look at this.

My immediate concern is that this could have been due to damage to the wwall and roof diap0hragm from either a large wind event or seismic - possibly the loss of a diaphragm chord tie? That needs to be looked at.

I am also wondering if the wall cells under the column were grouted to the extent required by the original designer.

Other than that. shore the column at least temporarily with a tube column and after-set bolt the column to the wall periodically.

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[Ron]

Agree with Mike...doesn't look like the cells were grouted. Check for ponding on the roof. The beam appears to be pulling inward, indicating a lot of deflection at or near midspan.

 

[IsaacStructural]

Thanks guys, I agree, it looks like the wall lacks a proper bearing pocket and possibly lacks any wall reinforcing whatsoever.

No significant rain or snow here right now, so if it from ponding, it must have occurred previously.

M.S. Structural Engineering
Licensed Structural Engineer and Licensed Professional Engineer (Illinois)

 

[hawkaz]

"will the expansion of the grout be enough to get a positive bearing under the beam"

No- The grout will shrink, not expand. You can get around this by leaving a gap between the bearing plate and grout, then using non-shrink drypack to fill the void.


SHORE THIS IMMEDIATELY!! Then solid grout (all the way to the ground) as many cells as needed.

 

[IsaacStructural]

I've got the word out to shore the structure until a better solution can be reached.

Sorry I should be more clear, I was referring to non shrink grout. I thought non shrink grouts had a larger volume when cured then when wet? can anyone confirm that?

If the owner can accept it in the space, I'm inclined to add a permanent post and foundation inside the wall and just tuck point the wall. After speaking with an experience masonry and concrete contractor I know, it sounds like the effort (cost) of grouting the wall in place most likely won't be worth it.

M.S. Structural Engineering
Licensed Structural Engineer and Licensed Professional Engineer (Illinois)

 

[hawkaz]

New post and footing is a good solution.
You are correct that drypack (non-shrink grout), such as 5 star does expand

 

[msquared48]

Thought... Could the beam be sitting on a steel pipe column embedded in the wall?

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[IsaacStructural]

I certainly think a post is a possibility, though probably won't know for sure until someone gets on site to check it out. The job is 3 hours drive away and so far we are only on the job as MEP consultants, so we don't really have the go ahead to do a deep structural investigation (yet).

M.S. Structural Engineering
Licensed Structural Engineer and Licensed Professional Engineer (Illinois)