16" vs 8" bond beams 1

[Texas Bricklady]

The bond beams span an 8'8" opening in a CMU wall.The drawings show 8" knockout bond beams. As a company that have done many buildings we felt we needed to use 16" horse collar (deep)bond beams. Also he had only one rebar that flowed all the way through and we added the second one to go all the way through too. We got permission to change the bond beam type both GC and owner agreed but now the architect (and his engineer) are saying we in fact weakend the structure. We of course strengthened it with the extra reinforcement.
Now we have to tear it out, get a structural engineer to agree that it's OK, or give them a lifetime guarantee instead of the standard 1 year warranty. Most architects understand the reasoning but he says he has never seen a 16" horsecollar and its not standard.
We are in Texas
Thanks

 

[Roukkia]

If it makes you feel any better, I can’t figure out why they’re rejecting it (with my limited couple years of design experience). I don’t think the block selection shown would violate any code requirements. Does the block have ASTM certification per the drawings? Block height is typically per the architect, so maybe they are not satisfied with the look?

How come y’all didn’t send an RFI?

 

[dik]

You usually use 16" deep U blocks for longer openings.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[kipfoot]

Probably the cheapest option for you is to give a 'lifetime warranty" because there's a low probability that you'll have to make good on it. That's a shady option, though, in my opinion, and one that should not be offered.

A better option would be to have a local engineer verify that this has sufficient capacity. Better still if it's the EOR who can do this as an additional service.

Maybe their capacity is based on the wall being grouted all the way up to the rake.

 

[Texas Bricklady]

Thanks guys. I couldn't understand why they rejected it either.
1. The bond beams were approved in the submittal stage.
2. The bond beams exceed the code for an 8" span

The architect says he has never seen these types of bond beams in his career. LOl

I think he is mad because he does not like the idea that we did not go by his drawings and is just butt-hurt.

Thanks for the input

 

[IceNine]

Since this is exposed split face block, there is a visual aspect to the change that the architect may not prefer.

 

[dflva]

I think he is mad because he does not like the idea that we did not go by his drawings and is just butt-hurt.

I'm sure you're right about the architect being mad. I suspect this is due to eliminating the joint at 8 in. above opening.

 

[DTS419]

If the bond beam is carrying a ridge beam reaction, shear will likely be an issue. The latest ACI provisions for shear strength really punish you if no stirrups are provided. This application might need a steel beam instead of CMU bond beam.

 

[Eng16080]

I'm not an expert in CMU design/construction, but in general, I don't see how your change would be problematic from a structural standpoint. Is there possibly an issue with the code not allowing a stack course here as opposed to running course? Being that it's grouted solid, I don't see why that would matter though.

Regardless of whether or not what you did works, I can definitely understand the architect being upset with this change being made behind their back. The engineer too for that matter.

I think he is mad because he does not like the idea that we did not go by his drawings and is just butt-hurt.

This is hardly surprising! Few things are more infuriating than this from an architect's or engineer's perspective. Often times a lot more effort and thought goes into the design than those constructing it would ever expect. Small changes like this, while seemingly simple, tend to be a lot more complicated than they appear. If nothing else, the change doesn't look great aesthetically.

Moving forward, if I were the architect/engineer, I would send a change order for redesigning this to ensure that the modification works. If it does and the owner is on-board (which they seemingly are), I would proceed with the change and be done with it.

 

[Aesur]

My thoughts are as follows:
1. Was the wall supposed to be solid grouted? If yes, maybe that is their concern.
2. Is there a bond beam at the roof line? It doesn't appear there is based on the shop drawing image, however maybe that is shown elsewhere. If there isn't, then there may be an issue.
3. Stack bond it typically weaker for shear, normally this affects shear walls, however in this case, it would affect gravity loading due to orientation, this could be easily checked by the EOR or another engineer.
4. Aesthetically, I'm sure the architect doesn't like it, I don't like it, but ultimately if the owner is ok with it, then it's their decision if everything checks out.
5. Was the EOR relying on arching effects, if so then they could recalculate without arching if needed.
6. Why is there no masonry control joint in this wall, while they can be detailed to avoid MCJ's, in my experience it's rare to design as such.
7. I suspect the EOR doesn't want to deal with it without being compensated for their time, it takes time to re-run calculations, even for something as simple as this. Maybe the cheapest option is to ask them what their fee would be to check this and offer to pay them for their time. I would anticipate this should be a cheap check however, so if they price high they just don't want to deal with it and hiring an outside engineer to check this may be difficult due to the unknowns, but not impossible. At the very least, I would put this in an RFI, asking for approval and detailed explanation why if it's not acceptable.

 

[BAretired]

I think he is mad because he does not like the idea that we did not go by his drawings and is just butt-hurt.

Does 'mad' mean 'angry' or 'crazy'?

 

[Once20036]

The bond beams were approved in the submittal stage.

If the bond beams were actually approved, how can they complain now? I suspect that they were not approved, even if your shop drawing showed them at 16" deep. The shop drawing stamp probably says something about general conformance with contract documents, but that you still have to follow the contract documents.

Now we have to tear it out, get a structural engineer to agree that it's OK, or give them a lifetime guarantee

This says to me that its not an aesthetic concern. 2 of the 3 options involve leaving it in place, as its currently installed. Nothing in there requires aesthetic approval from the owner.
Sounds to me like their concern is technical.

Also he had only one rebar that flowed all the way through and we added the second one to go all the way through too.

Maybe this is the trouble? The snip in the original post showed 2#5 in the lintel over the door + 2#5 in the full width bond beam above that.
If they expected 4#5 bars and you installed 1 plus 1 more, maybe that's the concern?

 

[Greenalleycat]

I'm pretty confused by this topic
What is your actual question to us?

 

[sandman21]

Thanks guys. I couldn't understand why they rejected it either.
1. The bond beams were approved in the submittal stage.
2. The bond beams exceed the code for an 8" span

The architect says he has never seen these types of bond beams in his career. LOl

I think he is mad because he does not like the idea that we did not go by his drawings and is just butt-hurt.

Thanks for the input

An architect not wanting to take responsibility for changes not authorized by them. I am shocked and that's not them being mad.

The 16" deep lintel block have the potential for pushing up the lintel bars reducing the capacity of lintel. Were they placed at proper depth? Did you place the bars to provide proper clearance to block shells? You added additional bars in a block that narrows. Did you provide proper clear between bars? Do the bars have proper clear from face shells? Not a single person will be able to tell you what impact the change has made without review. Go hire and engineer to review.

 

[JAE]

The EOR may be referring to a weakened system due to a vertical joint occurring directly in line with the edge of opening - thus, your CMU lintel is relying on shear through the grout only (vs. a running bond condition where a single CMU unit is half on the jamb and half over the opening.

ACI doesn't really apply here - NCMA does.

 

[hokie66]

The vertically oriented split face blocks look odd. And the stack bond is weaker than running bond. In this case, I agree that the as built wall is not acceptable.

 

[dik]

If the owner OK'd it, then you need the architect to issue a notice of change, and process it like a regular change order. When the architect gets the price for 'fixing', then the owner may not be happy with the additional cost. Do you have any confirmation that this was directed by the owner?

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[dik]

I'm not sure load is the issue... An 8'8" opening in a non-bearing wall is not a real serious design issue, except maybe in seismic areas.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[lexpatrie]

What Roukkia said, this should have been an RFI, not a "build it how you want and wait for somebody to notice." (this is somewhat similar to the Kansas City Walkway collapse, FYI).

Take the lesson.

I don't see anything dramatically wrong here, but the shop drawing approval usually says "deviance from the contract drawings is not approved" even if you showed it on a shop drawing. The alternate route is finding a friendly Civil/Structural P.E. (possibly the SER) to do calculations on it and ask for approval of the change.

Or just rip it out and do it the way they wanted it in the first place. If it wasn't clear in the original drawings, fine, then you can argue, otherwise, good luck.