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 (4) Calculate slenderness ratio of the column, adjust column
section to meet recommended ratio.
(5) Find load eccentricity in both directions and compare with
minimum eccentricity.
(6) Calculate balanced eccentricity in both directions from
Equation (58).
(7) Compute axial load capacity in both directions from
Equation (62) or (64).
(8) Compute pure axial load capacity of the section from
Equation (56).
(9) Find the ultimate capacity of the column section from
Equation (78>.
(10) Provide closed ties, according to paragraph 4.e.(7).
Calculation:
Given:
(1) Both ends fixed
(2) Column clear length, 120 in
(3) Axial load, 530,000 lb
Moment in x-x direction, 3,180,000 in-lb
No calculated moment in y-y direction
(4) Reinforcing steel yield stress, 60,000 psi
Compressive strength of concrete, 4,000 psi
Solution:
(1)
P = Axial Load x 1.2
= 530,000 x 1.2
= 636,000 lb
M = Moment x 1.2
Mx = 3,180,000 x 1.2
= 3,816,000 in-lb
My = 0 in-lb
(2) fdy = fy x DIF
= 60,000 x 1.10
= 66,000 psi
f'dc = f'c x DIF
= 4,000 x 1.25
= 5,000 psi
2.08-121
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