Civil Engineering Reference
In-Depth Information
“OK” if ww
“Not good”otherwise
≤
1
lim
Check_Crack1 :
=
Check_Crack1 = “OK”
7.8.2
Case 2—Midspan
Ratio of modulus of elasticity of bars to modulus of elasticity of concrete is
n
f
= 1.277
Ratio of depth of neutral axis to reinforcement depth is
k
2
= 0.135
Tensile stress in FRP under service loads assuming one layer of reinforce-
ment is
M
AAd1
k
3
s2
f:
=
15.5ksi
⋅
=
fs2
(
)
2
+
⋅
⋅
−
f2I
f f2II
f 2I
Ratio of distance from neutral axis to extreme tension fiber to distance
from neutral axis to center of tensile reinforcement is
hkd
d1k
−⋅
⋅
2
f2
β
:
=
1.089
=
(
)
12
−
f2
2
Thickness of concrete cover measured from extreme tension fiber to cen-
ter of bar is
d
c2
:= h - d
f2
= 2·in.
Bond factor (provided by the manufacturer):
k
b
= 0.9
The crack width under service loads is (Equation 8-9 of ACI 440.1R-06):
2
w: 2
f
E
+
s
fs2
f
2
f22
β⋅ ⋅
kd
=
0.013 in.
⋅
=
2
12
b
c2
2
The crack width limit for the selected exposure is
w
lim
= 0.028·in.
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