Civil Engineering Reference
In-Depth Information
fI
d
⋅
r
g
M:
=⋅
318 kipft
⋅
=
crNeg
g
The positive cracking moment is
fI
hd
⋅
−
r
g
M:
=⋅
149 kipft
⋅
=
crPos
g
Cracked moment of inertia:
The cracked moment of inertia, I
cr
, is com-
puted per Equation (8-11) of ACI 440.1R-06 at the following locations.
Case 1—Exterior support (includes presence of bends)
3
bd
3
⋅
(
)
2
w
f1
3
2
4
I:
k
+⋅
n
Ad
⋅
⋅
1k
−
= 4122 in
⋅
=
cr1
1new
f
f1newf1
1new
Case 2—Midspan
3
bd
3
⋅
(
)
2
w
f2
3
2
4
I:
k+nA d1k=4261 in
⋅
⋅
⋅
−
⋅
=
cr2
2
f
f2f2
2
Case 3—Interior support
3
bd
3
⋅
(
)
2
w
f3
3
2
4
I:
k+nA d1k=4991 in
⋅
⋅
⋅
−
⋅
=
cr3
3
f
f3f3
3
Reduction coefficients (modified Branson's method of ACI 440.1R-06):
Case 1—Exterior support
The reduction coefficient related to the reduced tension stiffening exhibited
in the FRP reinforced members, computed per Equation (8-13b) of ACI
440.1R is
1
5
ρ
ρ
f1
fb1
β
:
⋅
=0.137
=
d1
Case 2—Midspan
1
5
ρ
ρ
f2
fb2
β
:
⋅
=0.131
=
d2
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