Civil Engineering Reference
In-Depth Information
f
f
600
600
bal
c
y
ρ= β
0.85
and
f
y
is in MPa when S.I. units are used
(5.51b)
s
1
+
f
y
It is evident from Equation (5.48) that the more heavily reinforced the section is with
tension steel reinforcement, the less likely it is for the ductile crushing failure mode to
be admitted and the higher is the chance of the brittle failure mode to take place.
Example 5.8: Analysis
The beam section shown in Figure 5.11 is heavily reinforced with steel bars.
Determine the unstrengthened and strengthened moment capacity of this section.
f
4ksi
f
60 ksi
t
=
0.04"
Clear cover
=
1
=
=
c
y
f
Three layersofTyfoCFRPwrapped2"around the sides(Figure 5.11)
E
=
13,900 ksi
f
=
143 ksi
ε=
0.0008
f
fu
bi
Solution:
First check the failure mode likely to occur:
3
8
1
2
7
8
dd
t
== − −−×=
12"1.0
10.19"
87
87
87
87
bal
10.19
6.03"
c
=
d
=
×
=
+
f
+
60
y
=
×× ×+××× ×
×× + ×××
3160.04123220.04
11
d
f
=
11.8in
3160.043220.04
87
87
+
f
d
d
f
bal
y
f
ε=
0.003
−−ε
1
bi
d
c
11.8
6.03
f
bal
f
bal
ε=
0.003
−−ε=
1
0.003
−− =
1 .0008
0.00207
bi
16 in
12 in
6 # 7 bars
2 in
FIGURE 5.11
Example 5.8 showing the section details and the FRP suggested area.
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