Background Knowledge - Strengthening Design of Reinforced Concrete with FRP - page 31

Rectangular and square columns are designed for ties using imposed shear
forces, but no special confinement provision is added in this case. As a min-
imum, ACI 318-11 requires tie spacing to be the minimum of 16 times the
bar diameter, 48 times the tie diameter, or the least dimension of the column
(Section 7.10.5.2)

Example 2.5: Design
Design for minimum tie spacing in the following column:

f = 4,000 psi

c

f = 60,000 psi

y

f = 50,000 psi yt

Solution:

40.6
15

×
×

ρ= = 0.0107 > 0.01 O.K.

15

Use#3 ties

controls

7
8

16 d =×= 16 14 "

b

3
8

d

Spacing = min 48 =×= 48 18",

t

15"

Thus, use #3 ties at 14" c/c.

FIGURE 2.19 Square column cross section of Example 2.5.