Structural Concrete - Hassoun

References 353
Section 10.5
Minimum ratio of spirals is
⎧
⎪0.45
⎪
ρ s = ⎨
⎪
⎪
⎩
( ) Ag f
c
− 1
′
A f ch yt
4a s (D ch − d s )
D 2 ch S (Eq. 10.2)
The minimum diameter of spirals is 3 in., and the clear spacing should not be more than 3 in. or
8
less than 1 in.
Section 10.6
For tied columns,
or
For spiral columns,
or
where ρ g = A st ∕A g .
P u = φP n = 0.8φ[0.85f c(A ′ g − A st )+A st f y ] (Eq. 10.6)
P u = φP n = 0.8φA g [0.85f c ′ + ρ g (f y − 0.85f c)]
′
P u = φP n = 0.85φ[0.85f c(A ′ g − A st )+A st f y ] (Eq. 10.7)
P u = φP n = 0.85φA g [0.85f c ′ + ρ g (f y − 0.85f c)]
′
Section 10.7
1. For axial tension,
T u = φA st f y (φ = 0.9) (Eq. 10.11)
2. Arrangements of vertical bars and ties in columns are shown in Fig. 10.3.
REFERENCES
1. ACI Committee 315. Manual of Standard Practice for Detailing Reinforced Concrete Structures.American
Concrete Institute, Detroit, MI, 1999.
2. Concrete Reinforcing Steel Institute (CRSI). CRSI Handbook, 10th ed. CRSI, Chicago, IL, 2010.
3. B. Bresler and P. H. Gilbert. “Tie Requirements for Reinforced Concrete Columns.” ACI Journal 58
(November 1961), pp. 555–570.
4. J. F. Pfister. “Influence of Ties on the Behavior of Reinforced Concrete Columns.” ACI Journal 61 (May
1964), pp. 521–537.
5. N. G. Bunni. Rectangular Ties in Reinforced Concrete Columns. Publication No. SP–50. American Concrete
Institute, Detroit, MI, 1975.