MSJC "specified dimensions" for masonry

[TehMightyEngineer]

In the 2011 MSJC (TMS 402, ACI 530-11, ASCE 5-11) under Section 1.18.3.2.6 it says that the minimum wall horizontal and vertical reinforcement is to be based off of the gross cross-sectional area of the wall using specified dimensions.

Under definitions, the code lists:

Dimension, nominal - The specified dimension plus an allowance for the joints with which the units are to be laid. Nominal dimension are usually stated in whole numbers. Thickness is given first, followed by height and then length.

Dimension, specified - Dimensions specified for the manufacture or construction of a unit, joint, or element.

What is your interpretation of "specified dimension" in the context of Section 1.18.3.2.6?

Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries

https://www.facebook.com/AmericanConcrete/

 

[MotorCity]

My take.....specified dimension = actual, as constructed dimension

When it comes to determining reinforcing, it wont matter too much since you round off the reinforcement anyway.

For an 8" nominal block size, it would be a difference of 3/8" (8" nominal vs. 7 5/8" actual)

 

[TehMightyEngineer]

Okay, that matches my understanding as well. Just wanted to make sure I wasn't misunderstanding their intent.

Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries

https://www.facebook.com/AmericanConcrete/

 

[KootK]

I believe that they are saying:

1) don't subtract out the void space and;
2) use the specified thickness of the block.

Given that we almost always do this per unit length, the length of the wall is irrelevant.

So, as MC suggested, for an 8" wall it would be 7.625" x 12" x %.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.