1. Composite Construction
Detail of shear connectors

2. Composite Construction
PNA in steel
PNA in concrete b b
Ycon
Ycon a
C = Ccon+Cst
Tst
C=T
Mn = Cy = Ty b b a
C con
Ycon y
Tst

3. Composite Construction
Ccon = 0.85f’cba
T = FyAs
Ccon and T can not exceed force carried by studs, ∑Qn
∑Qn =0.85 f’cba
Depth of compression
block

4. Composite Members Specification p. 16.1-40
I3 Flexural Members
Effective Width, b, sum of effective widths for each side of beam center-line, each of which shall not exceed:
1) 1/8 of beam span
2) ½ distance to center-line of adjacent beam
3) distance to edge of slab b b b

5. Composite Members Specification p. 16.1-40
I3 Flexural Members (cont.)
Design Strength of Beams with Shear Connectors -
Strength During Construction
Formed Steel Deck
5a. General
hr ≤ 3” wr ≥ 2”
shear stud diameter ≤ ¾”
shear studs must extend 1½ -in. above top of deck
Slab thickness must be ≥ 2” above steel deck

6. Composite Members Specification p. 16.1-40
I3 Flexural Members (cont.)
Formed Steel Deck
5b. Deck Ribs Perpendicular to Steel Beam
Max shear stud spacing 36 in.
Shear stud strength reduction factor – eq. I3-1
≤0.75 if only single stud in rib
Deck must be anchored every 18 in.
5c. Deck Ribs Oriented Parallel to Steel Beam
Shear stud strength reduction factor – eq. I3-2
applied if wr/hr ≤1.5
Design Shear Strength

7. Composite Members Specification p. 16.1-40
I5 Shear Connectors – shear studs or channels
Length shear studs, Hs ≥ 4 stud diameters -
Strength of Stud Shear Connectors
Eq. I5-1 modified by reduction factors
Required Number of Connectors

8. Composite Members Specification p. 16.1-40
I5 Shear Connectors – shear studs or channels
Required Number of Connectors – Number required must be provided from section of maximum bending moment to adjacent section of zero moment.
Shear Connector Placement and Spacing
Stud diameter ≤2.5 tf (prevent tear out)
Minimum spacings
ribs parallel: longitudinal – 6 x stud diameter
transverse – 4 x stud diameter
ribs perpendicular: 4 x stud diameter (long. and trans.)
Maximum spacing 8 x slab thickness

9. Composite Construction p.5-33
Effective concrete
flange force (∑Qn)
Y1 – Distance from PNA to beam top flange
Y2 – Distance from concrete flange force to beam top flange
b – effective width of concrete slab flange
a – effective concrete flange thickness b
Ycon a Y2 Y1
PNA

10. Composite Design Example p. 39 notes
Redesign the floor system previously designed (example p. 33), using composite construction. A992 steel and 3500 psi concrete.