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CE591 Lecture 10: Composite Beams;
Shear Connectors; Metal Decking
Metal Deck, Shear Connectors
Shear Studs and Metal Deck
Capacity, Qn
Limits on Spacing, etc.
Calculation of Positive Design Flexural
Strength
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Metal Deck
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Thickness16 to 22 gage (~0.064 to ~0.034)
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Puddle welds
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AISC I3.2csteel deck shall be anchored to all
supporting members at a spacing not to exceed 18 (can
be from combination of shear studs and puddle welds)
Deck
manufacturersmay specify
placement
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Button-punching deck
http://www.vercodeck.com/index.php?option=com_content&view=article&id=267&Itemid=875
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Shear Connectors
From Geschwindner, Unified Design of Steel Structures, 2nded.
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Shear studs (steel headed stud
anchor) and ferrules
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Typically
3/4 or 7/8diameter
(3/4 required with
metal deck)
Height ~ 2 8
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Placing shear studs
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Welded wire fabric (WWF)
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Welded wire fabric
W1.4 x 1.4
6 x 6
Spacing (inches)
diameter of
wire, 10 gage,
d ~ 1/8
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May add reinforcement across girders
AISC C-I3.2where longitudinal cracking detrimental
to serviceability is likely to occur, slab should be
reinforced transverse to the supporting steel section ...
cr AA 002.0
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Shear Studs and Metal Deck
Ribs parallel to axis of beam Ribs perpendicular toaxis of beam
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Composite Floor System Design Techniques, 2013 NASCC
Will Jacobs, Sam Easterling
media.aisc.org/NASCC2013/N14a.mp4
http://media.aisc.org/NASCC2013/N14a.mp4http://media.aisc.org/NASCC2013/N14a.mp48/13/2019 CE591shearstuds_F13
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Ideallyrigid, no slip
Realitystud can
deform, concrete
crushes, get some slip
Q
d
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Strength of stud connectors for
composite beams
usapgccsan FARREfAQ '5.0
75.0
0.1
p
g
R
RNo metal deck?
Eq. (I8-1)
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(Easterling, 2007)
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wr
Hs hr
Hs=length of stud after welding
Hs
hr
+ 1-1/2
AISC I3.2c and I8.2
Hs 4ds
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From AISC-LRFD 3rdedition
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AISC Predicted Strength, QN
Exp
erimentalStu
dStrength,Q
e
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(Easterling, 2007)
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(Easterling, 2007)
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(Easterling, 2007)
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5.1r
r
h
w*0.85 if thru deck and ; 1.0 if 5.1
r
r
h
w
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Rp= 0.75
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ine htmid 2 ine htmid 2
Rp= 0.75 Rp= 0.6
emid-ht= distance from edge of stud shank to steel deck
web, measured at mid-height of the deck rib, and in the
load bearing direction (i.e. direction of max moment for
simply supported beam
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AISC
[16.1-98]
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(Easterling, 2007)
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(Easterling, 2007)
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Composite Floor System Design Techniques, 2013 NASCC
Will Jacobs, Sam Easterling
media.aisc.org/NASCC2013/N14a.mp4
http://media.aisc.org/NASCC2013/N14a.mp4http://media.aisc.org/NASCC2013/N14a.mp48/13/2019 CE591shearstuds_F13
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Limits
wr 2
Hs32 1-1/2
AISC I3.2cds (based on test results)
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wr 2 For one stud,
+ 4dsfor eachadditional stud
When nominal
hr 1-1/2
(AISC I3.2c)
Deck rib permitted
to be split
longitudinally and
separated to form aconcrete haunch
AISC I8.2d
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Limits, contd.
4 ds
2 ds (recommended)
6 ds (in general)
4 ds(for ribs perpendicular to beam)
8 tsand 36(in any direction)
5 minimum flange width for 2 rows of studs (for stud)8 minimum flange width for 3 rows of studs (for stud)
AISC I8.1
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Limits, contd.
fs td 5.2Unless stud placed over web
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Limits, contd.
AISC I8.2d
Lateral cover of 1
for shearconnectors,
except in ribs of
formed steel decks
1/2 reqd, ~1 typ.
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Calculation of fMn
Ribs perpendicular toaxis of beam
AISC I3.2c
Concrete below top of
deck (in ribs) shall be
neglected for section
properties and
calculation of Ac
(strength, etc.)
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Calculation of fMn
Ribs parallel to axis of beam
AISC I3.2c
Concrete below top of
deck (in ribs) is
permitted be included
for section properties
(Ix)
and SHALL be
included in calculationof Ac(strength)
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Lateral bracing during construction
(concrete placement)
With puddle welds / studs / combination at
no more than 18 o.c.
Beams are fully laterally braced Girders are perhaps not braced by the
deck
Depends on girderfiller beam detail
Recommend using filler beam spacing as
unbraced length at construction stage
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Composite Floor System Design Techniques, 2013 NASCC
Will Jacobs, Sam Easterling
media.aisc.org/NASCC2013/N14a.mp4
http://media.aisc.org/NASCC2013/N14a.mp4http://media.aisc.org/NASCC2013/N14a.mp4