Design Example 2. Calculate Transformed Moment of Inertia
Design Example 2. Calculate Transformed Moment of Inertia
Ec = (115 pcf) 3 ksi =
2136 ksi
n = Es / Ec = 29000/2136 = 13.6
de = (actual slab wt / conc. wt.) = 41 psf / 115 pcf.(12 in/ft)
= 4.3 in.
S/n
S
de
5.25"
20.66"
BEAM MODEL
W21x44
As = 13.0 in
Is = 84.3 in4
d = 20.66 in.
1.5
Distance from C.G. to slab top (Yt):
0.5 (10x12/13.6) (4.30) (4.30) + (13.0) (5.25 + 20.66/2.)
(10'x12/13.6) (4.3) + 13.0
= 5.6"
Yt =
It = (1/12 )(10'x12/13.6) (4.3") + (10x12/13.6)(4.3)(5.6 - 4.3/2) + 843 in +
+ (13.0 in )(20.66/2 + 5.25" - 5.6") = 58.5 + 451.6 + 843. + 1295 = 2648 in
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