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

2.7—Development and splices of reinforcing steel
2.7.1 General—In ACI 318 (318M), development and lap
splice lengths for deformed reinforcing bars can be calculated
using one of two optional approaches. A previous calcula-
tion approach, from ACI 318-89 (318M-89) also remains ac-
ceptable. With multiple code-compliant approaches to
calculation existing, choice, interpretation, and application
are the A/E’s responsibilities. Sufficient information shall be
presented on the structural drawings and in the project spec-
ifications to allow detailing of bars at splices and embedment
locations without referencing back to the code.
Tables in the supporting reference data section give values
of tension development lengths and tension lap splice lengths
of straight bars. Values of tension l
d
and tension lap splice
lengths in the tables are based on the provisions in ACI 12.2.2.
All tabulated data are for Grade 60 (420) reinforcing bars in
normalweight concrete with the concrete compressive
strength, f
′
c
, ranging from 3000 to 8000 psi (21 to 56 MPa).
The tables use the terminology Cases 1 and 2. Cases 1 and
2, which depend on the type of structural element, concrete
cover, and the center-to-center spacing of the bars, are also
defined in the tables.
Separate tables are included for uncoated and epoxy-coat-
ed bars. There are no special development requirements in
ACI 318 (318M) for zinc-coated (galvanized) bars and they
should be treated as uncoated bars. For lightweight aggre-
gate concrete, the values in the tables would have to be mod-
ified by the applicable factor (ACI 12.2.4).
ACI 1.2.1 requires that anchorage length of reinforcement
and location and length of lap splices be shown on the struc-
tural drawings. This information can be shown by dimen-
sioning cut-off locations and including tables of applicable
lap splice lengths.
2.7.2 Splices, general—In beams or girders that require
bars longer than can be carried in stock, splices shall be spec-
ified. The A/E shall show or specify by notes how the splic-
ing is to be realized; namely, lap splices, mechanical splices,
or welded splices.
The A/E shall also show, by details on structural drawings,
the location and length of all splices. In beams or girders,
splices should preferably be made where the stress in the bar
Spiral bar
diameter, in. 
(mm)
Minimum outside
diameter that can be 
formed, in. (mm)
Minimum outside
diameter of collapsible 
spiral, in. (mm)
3/8 (10)
9 (225)
14 (350)
1/2 (13)
12 (300)
18 (450)
5/8 (16)
15 (375)
24 (600)
3/4 (19)
30 (750)
—

---