Elements shall be
straight and free of any defects that would significantly affect
structural performance. Cold-formed steel floor framing members
shall be in accordance with the requirements of this section.
The provisions of this section
shall control the construction of cold-formed steel
floor framing for buildings not greater than 60 feet (18288
mm) in length perpendicular to the joist span, not greater
than 40 feet (12192 mm) in width parallel to the joist span
and less than or equal to three stories above grade plane.
Cold-formed steel floor framing constructed in accordance
with the provisions of this section shall be limited to sites
where the ultimate design wind speed is less than 139
miles per hour (62 m/s), Exposure Category B or C, and
the ground snow load is less than or equal to 70 pounds
per square foot (3.35 kPa).
Where supported by cold-formed
steel framed walls in accordance with Section
R603, cold-formed steel floor framing shall be constructed
with floor joists located in-line with load-bearing studs
located below the joists in accordance with Figure
R505.1.2 and the tolerances specified as follows:
The maximum tolerance shall be 3/4 inch (19.1 mm)
between the centerline of the horizontal framing member
and the centerline of the vertical framing member.
Where the centerline of the horizontal framing
member and bearing stiffener are located to one side
of the centerline of the vertical framing member, the
maximum tolerance shall be 1/8 inch (3 mm) between
the web of the horizontal framing member and the
edge of the vertical framing member.
Cold-formed steel trusses shall be
designed, braced and installed in accordance with AISI
S100, Section D4. In the absence of specific bracing
requirements, trusses shall be braced in accordance with
accepted industry practices, such as the SBCA Cold-Formed
Steel Building Component Safety Information
(CFSBCSI), Guide to Good Practice for Handling, Installing
& Bracing of Cold-Formed Steel Trusses. Truss members
shall not be notched, cut or altered in any manner
without an approved design.
Load-bearing cold-formed steel framing
members shall be cold formed to shape from structural quality
sheet steel complying with the requirements of ASTM
A1003: Structural Grades 33 Type H and 50 Type H.
Load-bearing cold-formed steel floor framing members
shall comply with Figure R505.2.3(1) and with the dimensional
and thickness requirements specified in Table
R505.2.3. Additionally, all C-shaped sections shall have a
minimum flange width of 1.625 inches (41 mm) and a
maximum flange width of 2 inches (51 mm). The minimum
lip size for C-shaped sections shall be 1/2 inch (12.7 mm). Track sections shall comply with Figure R505.2.3(2)
and shall have a minimum flange width of 11/4 inch (32 mm). Minimum Grade 33 ksi steel shall be used wherever
33 mil and 43 mil thicknesses are specified. Minimum
Grade 50 ksi steel shall be used wherever 54 and 68 mil
thicknesses are specified.
The member designation is defined by the first number representing the member depth in 0.01 inch, the letter "S" representing a stud or joist member, the
second number representing the flange width in 0.01 inch, and the letter "t" shall be a number representing the minimum base metal thickness in mils.
Screws for steel-to-steel connections
shall be installed with a minimum edge distance and center-to-center spacing of 1/2 inch (12.7 mm), shall be self-drilling
tapping, and shall conform to ASTM C1513. Floor sheathing
shall be attached to cold-formed steel joists with minimum
No. 8 self-drilling tapping screws that conform to
ASTM C1513. Screws attaching floor sheathing to cold-formed
steel joists shall have a minimum head diameter of
0.292 inch (7.4 mm) with countersunk heads and shall be
installed with a minimum edge distance of 3/8 inch (9.5 mm). Gypsum board ceilings shall be attached to cold-formed
steel joists with minimum No. 6 screws conforming
to ASTM C954 or ASTM C1513 with a bugle head style
and shall be installed in accordance with Section R702. For
all connections, screws shall extend through the steel a minimum
of three exposed threads. All fasteners shall have
rust-inhibitive coating suitable for the installation in which
they are being used, or be manufactured from material not
susceptible to corrosion.
Holes shall be permitted only along the centerline
of the web of the framing member.
Holes shall have a center-to-center spacing of not
less than 24 inches (610 mm).
Holes shall have a web hole width not greater
than 0.5 times the member depth, or 21/2 inches
(64.5 mm).
Holes shall have a web hole length not exceeding
41/2 inches (114 mm).
Holes shall have a minimum distance between
the edge of the bearing surface and the edge of
the web hole of not less than 10 inches (254 mm).
Framing members with web holes not conforming to
the above requirements shall be reinforced in accordance
with Section R505.2.6.2, patched in accordance
with Section R505.2.6.3 or designed in accordance with
accepted engineering practices.
Reinforcement of
web holes in floor joists not conforming to the requirements
of Section R505.2.6.1 shall be permitted if the
hole is located fully within the center 40 percent of the
span and the depth and length of the hole does not
exceed 65 percent of the flat width of the web. The reinforcing
shall be a steel plate or C-shape section with a
hole that does not exceed the web hole size limitations of
Section R505.2.6.1 for the member being reinforced.
The steel reinforcing shall be the same thickness as the
receiving member and shall extend not less than 1 inch
(25 mm) beyond all edges of the hole. The steel reinforcing
shall be fastened to the web of the receiving member
with No. 8 screws spaced not more than 1 inch (25 mm)
center-to-center along the edges of the patch with minimum
edge distance of 1/2 inch (12.7 mm).
Patching of web holes in floor joists not conforming to the requirements in Section R505.2.6.1 shall be permitted in accordance with either of the following methods:
Framing members shall be replaced or designed
in accordance with accepted engineering practices where web holes exceed the following size
limits:
The depth of the hole, measured across the
web, exceeds 70 percent of the flat width of
the web.
The length of the hole, measured along the
web, exceeds 10 inches (254 mm) or the
depth of the web, whichever is greater.
Web holes not exceeding the dimensional requirements
in Section R505.2.6.3, Item 1, shall be
patched with a solid steel plate, stud section or
track section in accordance with Figure
R505.2.6.3. The steel patch shall, as a minimum,
be of the same thickness as the receiving member
and shall extend not less than 1 inch (25 mm)
beyond all edges of the hole. The steel patch shall
be fastened to the web of the receiving member
with No. 8 screws spaced not more than 1 inch (25
mm) center-to-center along the edges of the patch
with minimum edge distance of 1/2 inch (12.7 mm).
For SI: 1 inch= 25.4 mm.
FIGURE R505.2.6.3
FLOOR JOIST WEB HOLE PATCH
Floor cantilevers for the top
floor of a two- or three-story building or the first floor of a
one-story building shall not exceed 24 inches (610 mm ...
