Page 293 - Civil Engineering Formulas

BUILDING AND STRUCTURES FORMULAS 227

C ≤ 1 Span
8 C C
Concrete ≤ 1 a
2
slab

a a

FIGURE 9.5 Limitations on effective width of concrete slab
in a composite steel-concrete beam.

least 1 in (25.4 mm) of concrete cover in all directions; and unless studs are
located directly over the web, stud diameters may not exceed 2.5 times the
beam-flange thickness.
With heavy concentrated loads, the uniform spacing of shear connectors
may not be sufficient between a concentrated load and the nearest point of
zero moment. The number of shear connectors in this region should be at least
N 1 [(M /M max ) 1]
N 2 (9.69)
1
where M moment at concentrated load, ft kip (kN m)
M max maximum moment in span, ft kip (kN m)
N number of shear connectors required between M max and zero moment
1
S /S or S /S , as applicable
s
tr
s
eff
3
3
S effective section modulus for partial composite action, in (mm )
eff
Shear on Connectors
The total horizontal shear to be resisted by the shear connectors in building con-
struction is taken as the smaller of the values given by the following two equations:
V h 0.85 f c A c (9.70)
2
A s F y
V h (9.71)
2
where V total horizontal shear, kip (kN), between maximum positive moment
h
and each end of steel beams (or between point of maximum posi-
tive moment and point of contraflexure in continuous beam)
f c specified compressive strength of concrete at 28 days, ksi (MPa)
2
2
A actual area of effective concrete flange, in (mm )
c
2
2
A area of steel beam, in (mm )
s