Aci 315-99 supersedes aci 315-92 and became effective August 31, 1999

 315-14
MANUAL OF CONCRETE PRACTICE
Radially prefabricated bars of any size tend to relax the ra-
dius originally prefabricated as a result of time and normal
handling. The last few feet involved in the lap splice area often
appear as a tangent rather than a pure arc, due to limitations of
standard bending equipment. For these reasons, final adjust-
ments are a field placing problem to suit conditions and toler-
ance requirements of a particular job. See 
Fig. 8 
and 
9 
for radial
tolerances and 
Section 4.2(c)3
. Bars requiring a larger radius
or length than shown in the table are sprung in the field with-
out prefabrication.
The presence of the tangent end does not create any prob-
lem on bar sizes No. 3 through 11 (No. 10 through 36) as
they are generally lap spliced and tangent ends are accept-
able. No. 14 and 18 (No. 43 and 57) bars cannot be lap
spliced, however, and are usually spliced using a proprietary
mechanical splice or a butt weld. It is a problem to place a
radially bent bar when using a mechanical splice sleeve be-
cause of the tangent ends on bars bent to small radii. To
avoid this problem, all No. 14 and 18 (No. 43 and 57) bars
bent to a radius of 20 ft (6000 mm) or less should be fur-
nished with an additional 18 in. (450 mm) added to each end.
This 18 in. (450 mm) tangent end is to be removed in the
field by flame cutting. Bars bent to radii greater than 20 ft
(6000 mm) will be furnished to the detailed length with no
consideration given to the tangent end. The ends of these
bars generally are saw cut.
Shop removal of tangent ends can be made by special ar-
rangement with the reinforcing bar supplier.
3.7.6 Slants—To determine the length of the straight bar
necessary to form a truss bar, the length of the slant portion
of the bar must be known. The standard angle is 45 degrees
for truss bars, with any other angles being special. Slants and
increments are calculated to the closest 1/2 in. (10 mm) so
that for truss bars with two slants, the total increment will be
in full inches (25 mm). This makes the computation easier
and is within the tolerances permitted. It is important to note
that when the height of the truss is too small, 45 degree bends
become impossible. This condition requires bending at a
lesser angle and lengthens the slant portion.