Civil Engineering Reference
In-Depth Information
“OK” if ww
“Not good”otherwise
≤
2
lim
Check_Crack2
:
=
Check_Crack2 = “OK”
7.8.3 Case 3—Interior support
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
3
= 0.209
Tensile stress in FRP under service loads is
M
s3
f:
=
16.637 ksi
⋅
=
fs3
k
3
3
Ad 1
⋅
⋅
−
f3
f3
Ratio of distance from neutral axis to extreme tension fiber to distance
from neutral axis to center of tensile reinforcement
hkd
d1k
−⋅
⋅
3
f3
β
:
=
1.097
=
(
)
13
−
f3
3
Thickness of concrete cover measured from extreme tension fiber to cen-
ter of bar is
d
c3
:= h - d
f3
= 2·in.
Bond factor (provided by the manufacturer) is
k
b
= 0.9
The crack width under service loads (Equation 8-9 of ACI 440.1R-06) is
2
w: 2
f
E
+
s
2
fs3
f
2
f3
β⋅ ⋅
kd
=
0.021 in.
⋅
=
3
13
b
c3
The crack width limit for the selected exposure is
w
lim
= 0.028·in.
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