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ANSI/SDI-C1.0 Standard for Composite Steel Floor Deck
loading case of wet concrete,
plus the weight of the steel
deck, plus 20 psf (1 kPa)
Commentary: Experience
has shown that 1-1/2 inches
(38 mm) of bearing is sufficient
for composite floor decks. If
less than 1-1/2 inches (38 mm) of
end bearing is available, or if high
support reactions are expected,
the design professional should
check the deck web crippling
capacity. The deck must be
adequately attached to the
structure to prevent slip off.
6. Diaphragm Shear Capacity:
Diaphragms without concrete
shall be designed in accordance
with the SDI Diaphragm Design
Manual, or from tests
conducted by an independent
professional engineer.
Commentary: Calculations of
diaphragm strength and stiffness
should be made using the SDI
Diaphragm Design Manual. If
testing is used as the means for
determining the diaphragm
strength and stiffness, then it
should follow the AISI TS 7-02
test protocol.
B. Deck and Concrete as a
Composite Slab:
1. General: The "SDI Method"
(refer to SDI Composite Deck
Design Handbook) shall be
limited to galvanized or
topside uncoated steel decks
with embossments. The
embossment patterns shall
be typical of the manufactured
steel deck with the depth of the
embossment not less than 90%
of the tested embossment
The composite slab shall be designed
as a reinforced concrete slab with
the steel deck acting as the positive
reinforcement. The deck must be
suitable to develop composite
interaction. Justification of this
requires full scale testing as per
ASTM E2322, or calculations based
upon testing.
a. Allowable Strength Design
(ASD) shall be permitted as an
alternate design method.
(See SDI Composite Deck
Design Handbook.
)
b. Standard reinforced concrete
design procedures shall be used
to determine ultimate load
capacity. The allowable
superimposed load shall then
be determined by deducting
the weight of the slab and the
deck. Attachment C4,
Strength and Serviceability
Determination of Composite
Deck Slab
shall be used for
strength determination.
Commentary: High concentrated
loads, diaphragm loads, etc. require
additional analysis. Horizontal
load capacities can be determined
by referring to the SDI Diaphragm
Design Manual. Concentrated loads
can be analyzed by the methods
shown in the SDI Composite Deck
Design Handbook. Most published
live load tables are based on
simple span analysis of the
composite system; that is, the
slab is assumed to crack over each
support.
2. Load Determination: Using
standard reinforced concrete
design procedures, the
allowable superimposed load
shall be found by using
appropriate load and
resistance design factors (LRFD)
and applicable reduction
factors based on the presence,
absence, or spacing of shear
studs on beams perpendicular
to the deck. (Refer to
Commentary: By using the
reference analysis techniques or
test results, the deck manufacturer
determines the live loads that can
be applied to the composite deck
slab combination. The results are
usually published as uniform load
tables. For most applications, the
deck thickness and profile is
selected so that shoring is not
required; the live load capacity of
the composite system is usually
more than adequate for the
superimposed live loads. In
calculating the section properties
of the deck, the AISI provisions may
require that compression zones in
the deck be reduced to an
"effective width," but as tensile
reinforcement, the total area of
(See attachment C5)
Coatings other than those tested
may be investigated, and if there
is evidence that their performance
is better than that of the tested
product, additional testing may
not be required.
3. Concrete: Concrete design
shall be in accordance with the
ACI Building Code
Requirements for Reinforced
Concrete. Minimum
compressive strength (f'c) shall
be a minimum of 3 ksi
(20 MPa) or as required for fire
ratings or durability.
Admixtures containing chloride
salts shall not be used.
Commentary: Load tables are
generally calculated by using a
concrete strength of 3 ksi (20 MPa).
Composite slab capacities are not
greatly affected by variations in
concrete compressive strength;
but, if the strength falls below
3 ksi (20 MPa) it would be advisable
to check shear stud strengths. Fire
rating requirements may dictate
the minimum concrete strength.
The use of admixtures containing
chloride salts is not allowed
because the salts will corrode the
steel deck.