Civil Engineering Reference
In-Depth Information
Round spiral columns.
(Courtesy of Economy Forms
Corporation.)
effective in increasing the ultimate column capacity as is longitudinal steel.
2,3
Therefore,
the strength of the spiral can be computed approximately by the following expression, in
which
s
is the percentage of spiral steel:
Spiral strength
2
s
A
c
f
y
Equating these expressions and solving for the required percentage of spiral steel, we
obtain
c
(
A
g
A
c
)
2
s
A
c
f
y
0.85
f
c
0.425
(
A
g
A
c
)
f
A
g
A
c
c
f
y
f
s
0.425
1
A
c
f
y
2
Park, A., and Paulay, T., 1975,
Reinforced Concrete Structures
(New York: John Wiley & Sons), pp. 25, 119-121.
3
Considere, A., 1902, “Compressive Resistance of Concrete Steel and Hooped Concrete, Part I,”
Engineering
Record
, December 20, pp. 581-583; “Part II,” December 27, pp. 605-606.
