Simplified Design for Columns - Simplified Design of Reinforced Concrete Buildings - page 177

Table 5-9 Reinforcement for Interior
Column of Building #2, Alternat (2)

Floor Required A st

(in 2 )

Reinforcement
( g %)

Required

g

(%)

5th (roof) 0.52 0.5 4- #6 (0.69)

4th 1.16 0.5 4- #6 (0.69)

3rd 1.76 0.69 4- #6 (0.69)

2nd 2 0.78 4- #7 (0.94)

1st 3.16 1.23 4- #8 (1.23)

Check for fire resistance: From Table 10-6, for a fire resistance rating of 4 hours or less, the required cover to
the main longitudinal reinforcement = 1.5 in. < provided cover. O.K.

Column ties and spacing can be selected from Table 5-3.

5.8.3 Example: Design of an Edge Column Stack (E-W Column Line) for Building

#1—3-story Pan Joist Construction (Sway Frame)

f c ʹ

= 4000 psi (carbonate aggregate)

f y = 60,000 psi

Required fire resistance rating = 1 hour (2 hours for columns supporting Alternate (2) floors).

(1) LOAD DATA

Roof: LL = 12 psf Floors: LL = 60 psf

DL = 105 psf DL = 130 psf

Calculations for the first story column are as follows:

(a) Total factored load (see Table 5-10):

Table 5-10 Edge Column Gravity Load Summary for Building #1

Floor Dead

Load
(psf)

Live
Load
(psf)

Tributary
Area
(sq ft)

Influence
Area

RM Reduced

Live Load
(psf)

Cumulative
Dead Load
(kips)

Cumulative
Live Load
(kips)

Cumulative
Factored
Load ACI
Eq. (9-2)
(kips)

3 rd (roof) 105 12 450 -- 1 12 51 5.4 64

2 nd 130 60 450 1800 0.6 36 114 21.6 165

1 st

130 60 450 3600 0.5 30 176 35.1 262