Civil Engineering Reference
In-Depth Information
Point A:
According to Equation (7.6)
f
cc
=
4.59
+ ×××
0.95
3.310.4343
=
5.95ksi
0.45
0.586 0.013
0.002
×
ε= ×+×× ×
0.002
1.51210.095
=
0.007162
ccu
Following Equation (7.1) with and without
ϕ
factors
π
4
P
n
=
0.85
× ×× −× +
5.95
11.960.31
2
61.360.31
× ×=
667.1kips
φ= ×
P
n
0.75
0.85
×
667.1
=
425.3kips
Point B:
2
nt E
D
ε
=
×× ×
2
20.015
11,306
×
0.004
fffe
f
=
=
0.228 ksi
l
11.9
This
f
l
will not be used to determine whether the stress-strain curve is
ascending or descending, since it is computed for eccentric points.
f
cc
=
4.59
+ ×××
0.95
3.310.228
=
5.3ksi
E
=
3861.7ksi,
E
=
154.44 ksi,
ε=
0.002476
c
2
t
0.45
0.004
0.002
ε= ×+××
0.002
1.51210.0497
×
=
0.004629
ccu
P
=
483.14 kips,
M
=
53.13 kip-ft
nB
,
nB
,
Point C:
P
=
286.86 kips,
M
=
78.75 kip-ft
nC
,
nC
,
Point D:
P
=
0kips,
M
=
38.54 kip-ft
, ,
Figure 7.14 presents the approximate interaction diagram computed according
to ACI 440.2R-08 procedure along with the value of the experimental point. It is
evident that the interaction diagram in Figure 7.14 is conservative with respect to
the experimental point.
nD
nD
On the other hand, Figure 7.15 depicts the interaction diagram according to the
KDOT Column Expert software. It is evident that the latter is in good agreement
with the experimental point. Also, it is clear that the interaction diagram com-
puted according to ACI 440.2R-08 is conservative with respect to that of KDOT
Column Expert in the overall sense. This should be expected to happen, since the
ACI440.2R-08 procedure accounts for FRP wrapping only and ignores the confine-
ment provided by the internal steel.
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