HELP! - Questions of Reinforced Brick Wall Design 3

[abusementpark]

I am designing a 10 foot tall exterior reinforced brick wall that cantilevers from the ground. The wall will consist of 4-3/8" thick concrete between two layers of 3-5/8" thick brick veneer. The nominal thickness of the wall is about 12". In the past, I have had thicker concrete layers and been able to neglect the contribution of brick. However, I think I need to utilize the brick here. I have a few questions about design and construction. Any help would be greatly appreciated.

- It is desirable to use the same brick veneer that will be used on the building. Does anyone know what a reasonable minimum compressive strength of the brick veneer would be?

- Also, I believe the brick veneer is usually cored. Does anyone know the typical core dimensions will be or at least a worst care scenario?

- I read the ACI/TMS provisions on composite action between the brick and the concrete. Does anyone know where could I find a design example for the checking the vertical shear for composite action. The cores in the brick veneer seems to really complicate the calculation. Does it typically govern? I might put double the required wall ties to help ensure composite behavior.

- Are there any precautions I need to take to reduce the potential for leaching?

Any other general tips are more than welcome!

 

[JedClampett]

Check this website. It has some very good technical notes:

http://www.gobrick.com/TechnicalNotes/LinkstoTechnicalNotes/tabid/11294/Default.aspx

They used to publish a textbook called "Recommended Practice for Engineered Brick Masonry" but I couldn't find it on the website.

 

[JAE]

There is a reference to this type of wall in BIA's technical note 45 (see Figure 20) but no specific structural design guidance.

Link to BIA TN 45

 

[JAE]

Check this out: Brick Retaining Walls Might be what you need.

 

[abusementpark]

Thanks for the links, guys. I found them to be helpful. However, I didn't see anything about protection against leaching. I guess I'll have to dig deeper.

 

[RareBugTX]

ASCE, ACI and TMS have the Masonry Designer's Guide with a lot of info and I prefer it to many textbooks. I am sure you can find a pdf on the net. It has a realm of info, design examples and properties.

 

[TXStructural]

What you describe is a common reinforced brick wall, but the material between brick wythes should be ASTM C476 grout, not really concrete. Strength testing is not required if it is mixed by proportion (1 part cement and 3 parts mason's sand, and may also contain 2 parts gravel, delivered at 8-11 inch slump AND NO STIFFER)

The holes in the brick are for manufacturing purposes and are ignored (as long as they comprise less than 25% of the brick.) The compressive strength of the brick is nominal over the gross brick area.

Look at technical notes 17, et seq.:

http://www.gobrick.com/TechnicalNotes/LinkstoTechnicalNotes/tabid/11294/Default.aspx

If you plan brick-concrete-brick, have you considered a concrete wall and applied thin brick? Clay brick expands over time and concrete shrinks over time. You may set up a restraint condition which will result in cracking of the brick.
ASCE article about problems with brick-concrete composite walls:

http://dx.doi.org/10.1061/41082(362)7

 

[abusementpark]

RareBugRA - Thanks for the tip. I didn't see it anywhere online on first glance, though.

TXStructural - Yes, I'm aware it should be "grout", not "concrete." Also, the brick used will be hollow facing brick per ASTM C652, so the holes cannot be neglected. I read tech note 17 and it found to be very helpful. I'd read that ASCE article if I could get access to it.

 

[dperaza]

It does sound like a very thin concrete wall or a cantilever. No chance of changing it to 8" reinforced CMU with 4" brick veneer on one side?

 

[abusementpark]

It does sound like a very thin concrete wall or a cantilever. No chance of changing it to 8" reinforced CMU with 4" brick veneer on one side?

The architect wants brick veneer on both sides and to minimize the overall thickness of the wall assembly.