Page 258 - Structural Steel Designers Handbook AISC, AASHTO, AISI, ASTM, and ASCE-07 Design Standards

Brockenbrough_Ch05.qxd 9/29/05 5:12 PM Page 5.38

CRITERIA FOR BUILDING DESIGN

5.38 CHAPTER FIVE

2
2
where A sc = cross-sectional area of stud shear connector, in (mm )
E c = modulus of elasticity of concrete, ksi (MPa)
F u = specified minimum tensile strength of a stud shear connector, ksi (MPa)
R g = 1.0 for one stud welded in a steel deck rib with the deck oriented perpendicular to the
steel shape; for any number of studs welded in a row directly to the steel shape; for
any number of studs welded in a row through steel deck with the deck oriented par-
allel to the steel shape and the ratio of the average rib width to rib depth ≥ 1.5
R g = 0.85 for two studs welded in a steel deck rib with the deck oriented perpendicular to
the steel shape; for one stud welded through steel deck with the deck oriented paral-
lel to the steel shape and the ratio of the average rib width to rib depth < 1.5
R g = 0.7 for three or more studs welded in a steel deck rib with the deck oriented perpen-
dicular to the steel shape
R p = 1.0 for studs welded directly to the steel shape (i.e., not through steel deck or sheet)
and having a haunch detail with not more than 50% of the top flange covered by deck
or sheet steel closures
R p = 0.75 for studs welded in a composite slab with the deck oriented perpendicular to the
beam and e mid-ht ≥ 2 in (51 mm); for studs welded through steel deck, or steel sheet
used as girder filler material, and embedded in a composite slab with the deck ori-
ented parallel to the beam
R p = 0.6 for studs welded in a composite slab with deck oriented perpendicular to the beam
and e mid-ht < 2 in (51 mm)
e mid-ht = distance from edge of stud shank to steel deck web, measured at mid-height of deck
rib, and in the load-bearing direction of the stud (i.e., direction of maximum moment
for simply supported beam), in (mm)
Channels welded to the steel beam may also be used as shear connectors. The welds must be
designed to develop the force Q n and the effects of eccentricity must be considered. The nominal
strength of one channel shear connector embedded in a solid concrete slab is
.
)
Q = 03.( t + 05 t L c f E ′ c c (5.139)
n
f
w
where t f = flange thickness of channel shear connector, in (mm)
t w = web thickness of channel shear connector, in (mm)
L c = length of channel shear connector, in (mm)
5.8.7 Concrete-Encased and Concrete-Filled Flexural Members
The design flexural strength φ b M n and allowable flexural strength M n /Ω b of concrete-encased and
concrete-filled sections may be determined by one of the following:
1. From the superposition of elastic stresses on the composite section, considering the effects of shoring,
for the limit state of yielding (yield moment), using φ b = 0.90 (LRFD) and Ω b = 1.67 (ASD).
2. From the plastic stress distribution on the steel section alone, for the limit state of yielding (plastic
moment), using φ b = 0.90 (LRFD) and Ω b = 1.67 (ASD).
3. From the plastic stress distribution on the composite section or from the strain-compatibility
method, if shear connectors are provided and the conditions of Art. 5.8.2 or 5.8.3 are met, using
φ b = 0.85 (LRFD) and Ω b = 1.76 (ASD).
As with composite slabs, when temporary shores are not used during construction, the steel sec-
tion alone must have adequate strength (see Art. 5.5) to support all loads applied prior to the con-
crete attaining 75% of its specified strength f c ′.
The available shear strength should be based on the shear strength of the steel section alone, plus
the shear strength of any tie reinforcement, or, alternatively, on the shear strength of the reinforced
concrete (see ACI 318).

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