3:28:26 PM.
Address: /showpage.php~file=06190700.htm.html
Title: Section 1907 • Size: 42844
Go to Table of Contents
Go to previous section: 1906
Go to next section: 1915
SECTION 1907 - DETAILS OF REINFORCEMENT
1907.0 Notations.
d = distance from extreme
compression fiber to centroid of tension reinforcement, inches
(mm).
=
nominal diameter of bar, wire or prestressing strand, inches (mm).
=
specified yield strength of nonprestressed reinforcement, psi
(MPa).
=
development length, inches (mm). See Section 1912.
1907.1 Standard Hooks. ``Standard
hook'' as used in this code is one of the following:
1907.1.1 One-hundred-eighty-degree
bend plus 4
extension, but not less than
2 1/2 inches (64 mm) at free end of bar.
1907.1.2 Ninety-degree
bend plus 12
extension at free end of
bar.
1907.1.3 For
stirrup and tie hooks:
1. No. 5 bar and smaller, 90-degree bend plus 6
extension at free end of bar, or
2. No. 6, No. 7 and No. 8 bar, 90-degree bend, plus
12
extension at free end of bar, or
3. No. 8 bar and smaller, 135-degree bend plus 6
extension at free end of bar.
4. For stirrup and tie hooks in Seismic Zones
3 and 4, refer to the hoop and crosstie provisions of Section
1921.1 and the transverse reinforcement.
1907.2 Minimum Bend Diameters.
1907.2.1 Diameter
of bend measured on the inside of the bar, other than for stirrups
and ties in sizes No. 3 through No. 5, shall not be less than
the values in Table 19-B.
1907.2.2 Inside
diameter of bends for stirrups and ties shall not be less than
4
for No. 5 bar and smaller. For bars
larger than No. 5, diameter of bend shall be in accordance with
Table 19-B.
1907.2.3 Inside
diameter of bends in welded wire fabric (plain or deformed) for
stirrups and ties shall not be less than
4
for deformed wire larger than D6 and
2
for all other wires. Bends with inside
diameter of less than 8
shall not be less
than 4
from nearest welded intersection.
1907.3 Bending.
1907.3.1 All
reinforcement shall be bent cold, unless otherwise permitted by
the building official.
1907.3.2 Reinforcement
partially embedded in concrete shall not be field bent, except
as shown on the design drawings or permitted by the building
official.
1907.4 Surface Conditions of
Reinforcement.
1907.4.1 At
the time concrete is placed, metal reinforcement shall be free
from mud, oil or other nonmetallic coatings that decrease bond.
1907.4.2 Metal
reinforcement, except prestressing tendons, with rust, mill scale
or a combination of both, shall be considered satisfactory, provided
the minimum dimensions (including height of deformations) and
weight of a hand-wire-brushed test specimen are not less than
applicable specification requirements.
1907.4.3 Prestressing
tendons shall be clean and free of oil, dirt, scale, pitting and
excessive rust. A light oxide is permissible.
1907.5 Placing Reinforcement.
1907.5.1 Reinforcement,
prestressing tendons and ducts shall be accurately placed and
adequately supported before concrete is placed, and shall be secured
against displacement within tolerances of this section.
1907.5.2 Unless
otherwise approved by the building official, reinforcement,
prestressing tendons and prestressing ducts shall be placed within
the following tolerances:
1907.5.2.1 Tolerance
for depth d, and minimum concrete cover in flexural members,
walls and compression members shall be as follows:
| TOLERANCE ON
d
| TOLERANCE ON MINIMUM
CONCRETE COVER
|
d  8 in. (203 mm)
| ± 3/8 in. (9.5 mm)
| - 3/8 in. (9.5 mm)
|
| d > 8 in. (203 mm)
| ± 1/2 in. (13 mm)
| - 1/2 in. (13 mm)
|
except that tolerance for the clear distance to formed
soffits shall be minus 1/4 inch (6.4 mm) and tolerance for cover
shall not exceed minus one third the minimum concrete cover required
by the approved plans or specifications.
1907.5.2.2 Tolerance
for longitudinal location of bends and ends of reinforcement shall
be ± 2 inches (± 51 mm) except at discontinuous ends
of members where tolerance shall be ± 1/2 inch(± 13
mm).
1907.5.3 Welded
wire fabric (with wire size not greater than W5 or D5) used in
slabs not exceeding 10 feet (3048 mm) in span may be curved from
a point near the top of slab over the support to a point near
the bottom of slab at midspan, provided such reinforcement is
either continuous over, or securely anchored at, support.
1907.5.4 Welding
of crossing bars shall not be permitted for assembly of reinforcement.
EXCEPTIONS: 1. Reinforcing
steel not required by design.
2. When specifically approved by the building
official, welding of crossing bars for assembly purposes in Seismic
Zones 0, 1 and 2 may be permitted, provided that data are submitted
to the building official to show that there is no detrimental
effect on the action of the structural member as a result of welding
of the crossing bars.
1907.6 Spacing Limits for Reinforcement.
1907.6.1 The
minimum clear spacing between parallel bars in a layer shall be
but not less than
1 inch (25 mm). See also Section 1903.3.2.
1907.6.2 Where
parallel reinforcement is placed in two or more layers, bars in
the upper layers shall be placed directly above bars in the bottom
layer with clear distance between layers not less than 1 inch
(25 mm).
1907.6.3 In
spirally reinforced or tied reinforced compression members, clear
distance between longitudinal bars shall not be less than 1.5
or less than 1 1/2 inches (38 mm). See also Section 1903.3.2.
1907.6.4 Clear
distance limitation between bars shall apply also to the clear
distance between a contact lap splice and adjacent splices or
bars.
1907.6.5 In
walls and slabs other than concrete joist construction, primary
flexural reinforcement shall not be spaced farther apart than
three times the wall or slab thickness, or 18 inches (457 mm).
1907.6.6 Bundled bars.
1907.6.6.1 Groups
of parallel reinforcing bars bundled in contact to act as a unit
shall be limited to four bars in one bundle.
1907.6.6.2 Bundled
bars shall be enclosed within stirrups or ties.
1907.6.6.3 Bars
larger than No. 11 shall not be bundled in beams.
1907.6.6.4 Individual
bars within a bundle terminated within the span of flexural members
shall terminate at different points with at least 40
stagger.
1907.6.6.5 Where
spacing limitations and minimum concrete cover are based on bar
diameter 
, a unit of bundled bars shall
be treated as a single bar of a diameter derived from the equivalent
total area.
1907.6.7 Prestressing tendons
and ducts.
1907.6.7.1 Clear
distance between pretensioning tendons at each end of a member
shall not be less than 4
for wire, or
3
for strands. See also Section 1903.3.2.
Closer vertical spacing and bundling of strands may be permitted
in the middle portion of a span.
1907.6.7.2 Posttensioning
ducts may be bundled if it is shown that concrete can be satisfactorily
placed and if provision is made to prevent the tendons, when tensioned,
from breaking through the duct.
1907.7 Concrete Protection for
Reinforcement.
1907.7.1 Cast-in-place concrete
(nonprestressed). The following minimum
concrete cover shall be provided for reinforcement:
MINIMUM COVER,
inches (mm)
| 1. |
Concrete cast against and permanently exposed to earth
| 3 (76) |
| 2. |
Concrete exposed to earth or weather:
No. 6 through No. 18 bar
No. 5 bar, W31 or D31 wire, and smaller
|
2 (51)
1 1/2 (38)
|
| 3. |
Concrete not exposed to weather or in contact with ground:
Slabs, walls, joists:
No. 14 and No. 18 bar
No. 11 bar and smaller
| 1 1/2 (38)
3/4 (19)
|
| Beams, columns:
Primary reinforcement, ties, stirrups, spirals
| 1 1/2 (38)
|
| Shells, folded plate members:
No. 6 bar and larger
No. 5 bar, W31 or D31 wire, and smaller
|
3/4 (19)
1/2 (13)
|
1907.7.2 Precast concrete
(manufactured under plant control conditions). The
following minimum concrete cover shall be provided for reinforcement:
MINIMUM COVER,
inches (mm)
| 1. |
Concrete exposed to earth or weather:
Wall panels:
No. 14 and No. 18 bar
No. 11 bar and smaller
Other members:
No. 14 and No. 18 bar
No. 6 through No. 11 bar
No. 5 bar W31 or D31 wire, and smaller
| 1 1/2 (38)
3/4 (19)
2 (51)
1 1/2 (38)
1 1/4 (32)
|
| 2. |
Concrete not exposed to weather or in contact with ground:
Slabs, walls, joists:
No. 14 and No. 18 bar
No. 11 bar and smaller
|
1 1/4 (32)
5/8 (16)
|
| Beams, columns:
Primary reinforcement
|
 but not less than 5/8 (16) and need not exceed 1 1/2 (38)
|
| Ties, stirrups, spirals
Shells, folded plate members:
No. 6 bar and larger
No. 5 bar, W31 or D31 wire, and smaller
| 3/8 (9.5)
5/8 (16)
3/8 (9.5)
|
1907.7.3 Prestressed concrete.
1907.7.3.1 The
following minimum concrete cover shall be provided for prestressed
and nonprestressed reinforcement, ducts and end fittings, except
as provided in Sections 1907.7.3.2
and 1907.7.3.3.
MINIMUM COVER,
inches (mm)
| 1. |
Concrete cast against and permanently exposed to earth
| 3 (76) |
| 2. | Concrete exposed to earth or weather:
Wall panels, slabs, joists
Other members
|
1 (25)
1 1/2 (32)
|
| 3. | Concrete not exposed to weather or in contact with ground:
Slabs, walls, joists
Beams, columns:
Primary reinforcement
Ties, stirrups, spirals
|
3/4 (19)
1 1/2 (38)
1 (25)
|
| Shells, folded plate members:
No. 5 bars, W31 or D31 wire, and smaller
Other reinforcement
|
3/8 (9.5)
 but not less than 3/4 (19)
|
1907.7.3.2 For
prestressed concrete members exposed to earth, weather or corrosive
environments, and in which permissible tensile stress of Section
1918.4.2, Item 2, is exceeded, minimum cover shall be increased
50 percent.
1907.7.3.3 For
prestressed concrete members manufactured under plant control
conditions, minimum concrete cover for nonprestressed reinforcement
shall be as required in Section 1907.7.2.
1907.7.4 Bundled bars. For
bundled bars, minimum concrete cover shall be equal to the equivalent
diameter of the bundle, but need not be greater than 2 inches
(51 mm); except for concrete cast against and permanently exposed
to earth, minimum cover shall be 3 inches (76 mm).
1907.7.5 Corrosive environments.
In corrosive environments or other severe
exposure conditions, amount of concrete protection shall be suitably
increased, and denseness and nonporosity of protecting concrete
shall be considered, or other protection shall be provided.
1907.7.6 Future extensions.
Exposed reinforcement, inserts and plates
intended for bonding with future extensions shall be protected
from corrosion.
1907.7.7 Fire protection.
When a thickness of cover for fire protection
greater than the minimum concrete cover specified in Section 1907.7
is required, such greater thickness shall be used.
1907.8 Special Reinforcement
Details for Columns.
1907.8.1 Offset bars. Offset
bent longitudinal bars shall conform to the following:
1907.8.1.1 Slope
of inclined portion of an offset bar with axis of column shall
not exceed 1 in 6.
1907.8.1.2 Portions
of bar above and below an offset shall be parallel to axis of
column.
1907.8.1.3 Horizontal
support at offset bends shall be provided by lateral ties, spirals
or parts of the floor construction. Horizontal support provided
shall be designed to resist one and one-half times the horizontal
component of the computed force in the inclined portion of an
offset bar. Lateral ties or spirals, if used, shall be placed
not more than 6 inches (152 mm) from points of bend.
1907.8.1.4 Offset
bars shall be bent before placement in the forms. See Section
1907.3.
1907.8.1.5 Where
a column face is offset 3 inches (76 mm) or greater, longitudinal
bars shall not be offset bent. Separate dowels, lap spliced with
the longitudinal bars adjacent to the offset column faces, shall
be provided. Lap splices shall conform to Section 1912.17.
1907.8.2 Steel cores. Load
transfer in structural steel cores of composite compression members
shall be provided by the following:
1907.8.2.1 Ends
of structural steel cores shall be accurately finished to bear
at end-bearing splices, with positive provision for alignment
of one core above the other in concentric contact.
1907.8.2.2 At
end-bearing splices, bearing shall be considered effective to
transfer not more than 50 percent of the total compressive stress
in the steel core.
1907.8.2.3 Transfer
of stress between column base and footing shall be designed in
accordance with Section 1915.8.
1907.8.2.4 Base
of structural steel section shall be designed to transfer the
total load from the entire composite member to the footing; or,
the base may be designed to transfer the load from the steel core
only, provided ample concrete section is available for transfer
of the portion of the total load carried by the reinforced concrete
section to the footing by compression in the concrete and by reinforcement.
1907.9 Connections.
1907.9.1 At
connections of principal framing elements (such as beams and columns),
enclosure shall be provided for splices of continuing reinforcement
and for end anchorage of reinforcement terminating in such connections.
1907.9.2 Enclosure
at connections may consist of external concrete or internal closed
ties, spirals or stirrups.
1907.10 Lateral Reinforcement
for Compression Members.
1907.10.1 Lateral
reinforcement for compression members shall conform to the provisions
of Sections 1907.10.4 and
1907.10.5 and, where shear
or torsion reinforcement is required, shall also conform to provisions
of Section 1911.
1907.10.2 Lateral
reinforcement requirements for composite compression members shall
conform to Section 1910.14. Lateral reinforcement requirements
for prestressing tendons shall conform to Section 1918.11.
1907.10.3 Lateral
reinforcement requirements of Sections 1907.10,
1910.14 and 1918.11 may be waived where tests and structural analyses
show adequate strength and feasibility of construction.
1907.10.4 Spirals. Spiral
reinforcement for compression members shall conform to Section
1910.9.3 and to the following:
1907.10.4.1 Spirals
shall consist of evenly spaced continuous bar or wire of such
size and so assembled as to permit handling and placing without
distortion from designed dimensions.
1907.10.4.2 For
cast-in-place construction, size of spirals shall not be less
than 3/8-inch (9.5 mm) diameter.
1907.10.4.3 Clear
spacing between spirals shall not exceed 3 inches (76 mm) or be
less than 1 inch (25 mm). See also Section 1903.3.2.
1907.10.4.4 Anchorage
of spiral reinforcement shall be provided by one and one-half
extra turns of spiral bar or wire at each end of a spiral unit.
1907.10.4.5 Splices
in spiral reinforcement shall be lap splices of 48
,
but not less than 12 inches (305 mm) or welded.
1907.10.4.6 Spirals
shall extend from top of footing or slab in any story to level
of lowest horizontal reinforcement in members supported above.
1907.10.4.7 Where
beams or brackets do not frame into all sides of a column, ties
shall extend above termination of spiral to bottom of slab or
drop panel.
1907.10.4.8 In
columns with capitals, spirals shall extend to a level at which
the diameter or width of capital is two times that of the column.
1907.10.4.9 Spirals
shall be held firmly in place and true to line.
1907.10.5 Ties. Tie
reinforcement for compression members shall conform to the following:
1907.10.5.1 All
nonprestressed bars shall be enclosed by lateral ties, at least
No. 3 in size for longitudinal bars No. 10 or smaller, and at
least No. 4 in size for Nos. 11, 14 and 18 and bundled longitudinal
bars. Deformed wire or welded wire fabric of equivalent area may
be used.
1907.10.5.2 Vertical
spacing of ties shall not exceed 16 longitudinal bar diameters,
48 tie bar or wire diameters, or least dimension of the compression
member.
1907.10.5.3 Ties
shall be arranged such that every corner and alternate longitudinal
bar shall have lateral support provided by the corner of a tie
with an included angle of not more than 135 degrees and a bar
shall be not farther than 6 inches (152 mm) clear on each side
along the tie from such a laterally supported bar. Where longitudinal
bars are located around the perimeter of a circle, a complete
circular tie may be used.
1907.10.5.4 Ties
shall be located vertically not more than one half a tie spacing
above the top of footing or slab in any story and shall be placed
as provided herein to not more than one half a tie spacing below
the lowest horizontal reinforcement in members supported
above.
1907.10.5.5 Where
beams or brackets frame from four directions into a column, ties
may be terminated not more than 3 inches (76 mm) below lowest
reinforcement in shallowest of such beams or brackets.
1907.10.5.6 Column
lateral ties shall be as specified in Section 1907.1.3,
Item 3.
1907.11 Lateral Reinforcement
for Flexural Members.
1907.11.1 Compression
reinforcement in beams shall be enclosed by ties or stirrups satisfying
the size and spacing limitations in Section 1907.10.5
or by welded wire fabric of equivalent area. Such ties or stirrups
shall be provided throughout the distance where compression reinforcement
is required.
1907.11.2 Lateral
reinforcement for flexural framing members subject to stress reversals
or to torsion at supports shall consist of closed ties, closed
stirrups, or spirals extending around the flexural reinforcement.
1907.11.3 Closed
ties or stirrups may be formed in one piece by overlapping standard
stirrup or tie end hooks around a longitudinal bar, or formed
in one or two pieces lap spliced with a Class B splice (lap of
1.3 
), or anchored in accordance with
Section 1912.13.
1907.12 Shrinkage and Temperature
Reinforcement.
1907.12.1 Reinforcement
for shrinkage and temperature stresses normal to flexural reinforcement
shall be provided in structural slabs where the flexural reinforcement
extends in one direction only.
1907.12.1.1 Shrinkage
and temperature reinforcement shall be provided in accordance
with either Section 1907.12.2
or 1907.12.3 below.
1907.12.2 Deformed
reinforcement conforming to Section 1903.5.3
used for shrinkage and temperature reinforcement shall be provided
in accordance with the following:
1907.12.2.1 Area
of shrinkage and temperature reinforcement shall provide at least
the following ratios of reinforcement area to gross concrete area,
but not less than 0.0014:
| 1. Slabs where Grade 40 or 50 deformed bars are used
| 0.0020
|
| 2. Slabs where Grade 60 deformed bars or welded wire fabric (smooth or deformed) are used
| 0.0018
|
| 3. Slabs where reinforcement with yield stress exceeding
| |
60,000 psi (413.7 MPa) measured at a yield strain of 0.35 percent is used 
|
| For SI: | 
| |
1907.12.2.2 Shrinkage
and temperature reinforcement shall be spaced not farther apart
than five times the slab thickness, or 18 inches (457 mm).
1907.12.2.3 At
all sections where required, reinforcement for shrinkage and temperature
stresses shall develop the specified yield strength 
in tension in accordance with Section 1912.
1907.12.3 Prestressing
tendons conforming to Section 1903.5.5
used for shrinkage and temperature reinforcement shall be provided
in accordance with the following:
1907.12.3.1 Tendons
shall be proportioned to provide a minimum average compressive
stress of 100 psi (0.69 MPa) on gross concrete area using effective
prestress, after losses, in accordance with Section 1918.6.
1907.12.3.2 Spacing
of prestressed tendons used for shrinkage and temperature reinforcement
shall not exceed 6 feet (1829 mm).
1907.12.3.3 When
the spacing of prestressed tendons used for shrinkage and temperature
reinforcement exceeds 54 inches (1372 mm), additional bonded shrinkage
and temperature reinforcement conforming with Section 1907.12.2
shall be provided between the tendons at slab edges extending
from the slab edge for a distance equal to the tendon spacing.
Go to Table of Contents
Go to previous section: 1906
Go to next section: 1915