Effective Masonry Wall Thickness

[EIT2]

How does one determine the effective concrete masonry wall thickness, for direct compression, for varied spacings of grouted cells and varied, nominal, concrete masonry wall thicknesses?

Through one example, in a design manual, a 7.625" wall with grouted cells at 24" oc is stated to have an effective wall thickness of 5.2". This statement has no resource or table reference, within the manual, to support this stated value.

I have a 12" wall with reinforced, grouted cells at 16" oc.
The design example in this manual is of no use if I cannot determine the effective wall thickness.

Thank you!

 

[whymrg]

National Concrete Masonry Association (NCMA)has many publications called TEK. NCMA-TEK 14-1 "Section Properties of Concrete Masonry Walls" has Areas, Moments of Inertia, Section Modulus and Radius of Gyration for walls with different thicknesses and grouted core spacing.

For 12" wall with grouted cells at 16", Effective area equal to 85.3 sq.in./ft.

Try to get this publication for your masonry needs.

 

[dik]

Are you looking for the effective area? or wall thickness? Effective area (as well as effective S and I) can be calculated fairly easily. If it's the equivalent thickness, is it for fire-rating or with a ribbed block (or something of that ilk) for stability (h/t)?

 

[EIT2]

To "whymrg" and "dik":

Thank you very much for your response(s). (I do have NCMA-TEK 141B, which is the original TEK for "Section Properties of Concrete Masonry Walls" prior to the revised NCMA-TEK 14-1. I do not have 14-1. Does it show effective wall thickness?)

I am looking for the effective wall thickness.

I need to design a concrete masonry wall for axial and bending. Typically, I use engineering software. However, the unsupported height is 48.00' and the program does not allow me to enter more than one vertical rebar per cell.

The design example in my design manual for reinforced masonry structures, shows the axial load being divided by the effective wall thickness, which, in the example, is 5.2" for a nominal thickness of 8".

Any further support will be very much appreciated.

Thank you, again!

 

[dik]

Is the wall ribbed? or just conventional masonry units, and how thick?

 

[EIT2]

To "dik":

12" full split-faced concrete masonry.

Thank you!

 

[haynewp]

7.625"x24"-2x30in^2(approx. area of cells not filled)=123in^2

EST=123/24=5.125

 

[haynewp]

http://www.angelusblock.com/wts-area.cfm

 

[EIT2]

haynewp:

Thank You!

EIT2