Introduction - Design of Reinforced Concrete - page 24

Table A.3(A) in the Appendix provides information concerning certain styles of
welded wire fabric that have been recommended by the Wire Reinforcement Institute as
common stock styles (normally carried in stock at the mills or at warehousing points and
thus usually immediately available). Table A.3(B) in the Appendix provides detailed in-
formation as to diameters, areas, weights, and spacings of quite a few wire sizes normally
used to manufacture welded wire fabric. Smooth and deformed wire fabric is made from
wires whose diameters range from 0.134 in. up to 0.628 in. for plain wire and from 0.225
in. up to 0.628 in. for deformed wires.
Smooth wire is denoted by the letter W followed by a number that equals the cross-
sectional area of the wire in hundredths of a square inch. Deformed wire is denoted by the
letter D followed by a number giving the area. For instance, a D4 wire is a deformed wire
with a cross-sectional area equal to 0.04 in. Smooth wire fabric is actually included within
the ACI Code's definition of deformed reinforcement because of its mechanical bonding
to the concrete caused by the wire intersections. Wire fabric that actually has deforma-
tions on the wire surfaces bonds even more to the concrete because of the deformations as
well as the wire intersections.
The fabric is usually indicated on drawings by the letters WWF followed by the spac-
ings of the longitudinal wires and the transverse wires and then the total wire areas in
hundredths of a square inch per foot of length. For instance, WWF6

8 rep-
resents smooth welded wire fabric with a 6-in. longitudinal and a 12-in. transverse spac-
ing with cross-sectional areas of 0.32 in. 2 /ft and 0.08 in. 2 /ft, respectively.

12-W16

1.16 GRADES OF REINFORCING STEEL

Reinforcing bars may be rolled from billet steel, axle steel, or rail steel. Only occasion-
ally, however, are they rolled from old train rails or locomotive axles. These latter steels
have been cold-worked for many years and are not as ductile as the billet steels.
There are several types of reinforcing bars, designated by the ASTM, which are listed
after this paragraph. These steels are available in different grades as Grade 50, Grade 60,
and so on, where Grade 50 means the steel has a specified yield point of 50,000 psi, Grade
60 means 60,000 psi, and so on.

1. ASTM A615: Deformed and plain billet steel bars. These bars, which must be
marked with the letter S (for type of steel), are the most widely used reinforcing
bars in the United States.
2. ASTM A706: Low alloy deformed and plain bars. These bars, which must be
marked with the letter W (for type of steel), are to be used where controlled ten-
sile properties and/or specially controlled chemical composition is required for
welding purposes.
3. ASTM A996: Deformed rail steel or axle steel bars. They must be marked with
the letter R (for type of steel).
4. When deformed bars are produced to meet both the A615 and A706 specifica-
tions, they must be marked with both the letters S and W.

Designers in almost all parts of the United States will probably never encounter
rail or axle steel bars (A996) because they are available in such limited areas of the