Civil Engineering Reference
In-Depth Information
Problem 9.8
Design of Axially Loaded Columns
In Problems 9.10 to 9.15 design columns for axial load
only. Include the design of ties or spirals and a sketch of
the cross sections selected, including bar arrangements.
All columns are assumed to be short and are not exposed
to the weather.
9.10
Square tied column:
P
D
280 k,
P
L
500 k,
4000 psi, and
f
y
60,000 psi. Initially assume
g
2%.
9.11
Repeat Problem 9.10 if
g
is to be 4% initially. (
One
ans.
20 in.
20 in. column with 10 #11 bars)
9.12
Round spiral column;
P
D
300 k,
P
L
350 k,
3500 psi, and
f
y
60,000 psi. Initially assume
g
4%.
9.13
Round spiral column;
P
D
300 k,
P
L
350 k,
4000 psi,
f
y
60,000 psi, and
g
initially assumed
2%. (
One ans.
21 in. diameter column with 7 #9 bars)
9.14
Smallest possible square tied column;
P
D
200 k,
P
L
300 k,
4000 psi, and
f
y
60,000 psi.
9.15
Design a rectangular tied column with the long side
equal to two times the length of the short side.
P
D
650,
P
L
400 k,
3000 psi,
f
y
60,000 psi, and initially
assume that
g
2%. (
One ans.
20 in.
40 in. column
with 8 #11 bars)
6 #11
bars
24"
c
f
a spiral
column
Problem 9.9
Determine the load-bearing capacity of the
concentrically loaded short column shown if
f
y
60,000
psi and
c
f
c
3000 psi. (
Ans.
982.3 k)
f
3"
c
f
4 #11
14"
20"
c
f
3"
3"
3"
24"
c
f
30"
Problems in SI Units
In Problems 9.16 to 9.18 design columns for axial load
only for the conditions described. Include the design of
ties or spirals and a sketch of the cross sections selected,
including bar arrangements. All columns are assumed to
be short and not exposed to the weather.
9.16
Square tied column;
P
D
600 kN,
P
L
800 kN,
24 MPa, and
f
y
420 MPa. Initially assume
g
0.02.
9.17
Smallest possible square tied column;
P
D
700 kN,
P
L
300 kN,
28 MPa, and
f
y
300 MPa. (
One
ans.
250 mm
250 mm column with six #29 bars)
c
f
9.18
Round spiral column;
P
D
500 kN,
P
L
650 kN,
35 MPa, and
f
y
c
c
f
f
420 MPa. Initially assume
g
0.03.
For Problems 9.19 to 9.21 use the SABLE32 program.
Assume
d
2.5 in. for each column.
9.19
Repeat Problem 9.6 (
Ans.
P
n
629 k)
9.20
Repeat Problem 9.10.
9.21
Repeat Problem 9.14. (
One ans.
14
14 in. column
for which
P
n
720 k)
