Friday, September 9, 2011

RE: Old Structural Mesh BF912

Yes, I know because I asked the same question in the late 1970's.
In that time period (1930's and 1940's) WWR spacing was called out in letter indicators for spacing as follows:
Designation:     Spacing:
A                          2"
B                          4"
C                          6"
D                          8"
E                          10"
F                          12"
The first number following the letters was the gauge of the wire in the first alphanumeric spacing
The second number in the sequence corresponded to the gauge in the second alphanumeric spacing
Thus BF912 was WWF 4 x 12 - 9/12  in gauge
WWR 4 x 12 - W 1.7 x W 0.9 in current designation in square in per ft. 
The WWR you are indicating was desigened to be reinforcing in one direction and for temperature in the opposite direction in slabs spanning one way.  This information was passed down to me a long time ago by an engineer older and much wiser than me.   I wrote it down in my 1950's vintage CRSI. 
...Al Towner was his name. 

Regards, Harold Sprague

We are working on a project that involves an existing reinforced concrete building with the drawings dated 1937.  The reinforcing specified for 3" slab over joists is BF912 Mesh.  Does anyone know BF912 Mesh?
Martin Li, P.E.
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