Structural Concrete - Hassoun

10.8 Long Columns 351
3. Design of ties (by ( calculation ) or from Table ( ) 10.1): Choose no. 3 ties with spacings equal to the
least of S 1 = 16 10
= 20 in., S
8
2 = 48 3
= 18 in., or S
8 3 = column side = 16 in. Use no. 3 ties
spaced at 16 in. Clear distance between bars is 4.25 in., which is less than 6 in. Therefore, no
additional ties are required.
Example 10.3
Repeat Example 10.2 using a rectangular section that has a width of b = 14 in.
Solution
1. P u = 851 K and calculated A g = 232.5 in. 2 For b = 14 in., h = 232.5/14 = 16.6 in. Choose a column
14 × 18 in.; actual A g = 252 in. 2 .
2. P u = 851 = 0.65(0.8)[0.85 × 5 × 252 + A st (60 − 0.85 × 5)].
A st = 10.14 in. 2
Use eight no. 10 bars (A st = 10.16 in. 2 ).
3. Design of ties: Choose no. 3 ties, S 1 = 20 in., S 2 = 18 in., and S 3 = 14 in. (least side). Use no. 3
ties spaced at 14 in. Clear distance between bars in the long direction is (18 – 5)/2-bar diameter
of 1.27 = 5.23 in.