Composite Construction Detail of shear connectors Composite Construction
- Slides: 10
Composite Construction • Detail of shear connectors
Composite Construction PNA in steel b a Ycon C = Ccon+Cst Tst C=T PNA in concrete b Ycon Mn = Cy = Ty a C con y Tst
Composite Construction Ccon = 0. 85 f’cba T = Fy. As Ccon and T can not exceed force carried by studs, ∑Qn =0. 85 f’cba Depth of compression block
Composite Members Specification p. 16. 1 -40 I 3 Flexural Members 1. 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
Composite Members Specification p. 16. 1 -40 I 3 Flexural Members (cont. ) 2. Design Strength of Beams with Shear Connectors 3. 4. Strength During Construction 5. Formed Steel Deck 5 a. 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
Composite Members Specification p. 16. 1 -40 I 3 Flexural Members (cont. ) 5. Formed Steel Deck 5 b. Deck Ribs Perpendicular to Steel Beam Max shear stud spacing 36 in. Shear stud strength reduction factor – eq. I 3 -1 ≤ 0. 75 if only single stud in rib Deck must be anchored every 18 in. 5 c. Deck Ribs Oriented Parallel to Steel Beam Shear stud strength reduction factor – eq. I 3 -2 applied if wr/hr ≤ 1. 5 6. Design Shear Strength
Composite Members Specification p. 16. 1 -40 I 5 Shear Connectors – shear studs or channels 1. Length shear studs, Hs ≥ 4 stud diameters 2. 3. Strength of Stud Shear Connectors Eq. I 5 -1 modified by reduction factors 4. 5. Required Number of Connectors
Composite Members Specification p. 16. 1 -40 I 5 Shear Connectors – shear studs or channels 5. Required Number of Connectors – Number required must be provided from section of maximum bending moment to adjacent section of zero moment. 6. 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
Composite Construction p. 5 -33 Effective concrete flange force (∑Qn) • Y 1 – Distance from PNA to beam top flange • Y 2 – Distance from concrete flange force to beam top flange • b – effective width of concrete slab flange • a – effective concrete flange thickness b Ycon a Y 2 Y 1 PNA
Composite Design Example p. 39 notes Redesign the floor system previously designed (example p. 33), using composite construction. A 992 steel and 3500 psi concrete.
