Civil Engineering Reference
In-Depth Information
Theoretically between 1.73 ft (20.8”) and 3.73 ft
Practically between 1.73 ft and 9.9 ft
φ=
×××
0.75
0.450
19.75
V
s
=
32.92 k
9
(
)
φ+ =
VV
c
22.48
+
32.92
=
55.4k
s
3
(
)
Determin
ex
dis efrom orttoV
tan
sup
=φ +
VV
cs
3
u
c
s
3
(
)
φ+ =
VV
55.4
=
Vwx
−
c
s
3
u
u
cs
3
98
55.4
7
−
x
cs
=
=
6.09' outside 9.9'-11.96'
where steel stirrup spacing
=
6"
3
(i.e., no need for FRP between 9.9 ft and 12 ft)
(
)
Vwx
−
= −× =
98
79.9
28.7
k
<φ+ =
VV
55.4k
O.K.
u
u
c
c
s
3
V
=−×=
98
71214k
u
11.96
−
φ
V
V
c
98
−
11.24
7
u
2
x
12.39 ft
=
=
=
c
4
w
u
Between 12' and 12.4' we need FRP
Use1layer of 13" @ 18" c/cfor this distance ( 4clear spacing)
d
Practically use one layer of 13" @ 18" o.c. between 9.9 ft and 12.9 ft (three U-wraps
within 3 ft).
Check the reinforcement limit:
=
××
=
0.450
19.75
V
65.83 k
s
2
6
=
×× ×× ×
210.0065
13
33,000
0.238
×
0.0158
×
15.75
V
=
22.02 k
f
15
VV
+= <
87.85k84,000
×
12
×
19.75
=
119,913.57 lb
=
119.913 k
.K.
s
2
f
Example 6.2: Design
The column in Example 2.4 is located in a building that underwent a change in
its importance category from Regular Building to Essential Facility. The loads were
increased as follows:
M
u
=
84.38 k-ft
M
u
=
84.38 k-ft
V
u
=
18.75 k
V
u
=
18.75 k
P
u
=
18 7. 5 k
P
u
=
24 k
Figure 6.4 shows the column section and profile.
f
=
4ksi
f
=
40 ksi
c
yt
Search WWH ::
Custom Search