Civil Engineering Reference
In-Depth Information
5.8
EXAMPLES: SIMPLIFIED DESIGN FOR COLUMNS
The following examples illustrate the simplified methods presented in this chapter.
5.8.1
Example: Design of an Interior Column Stack for Building #2 Alternate (1)—
Slab and Column Framing Without Structural Walls (Sway Frame)
› = 4000 psi (carbonate aggregate)
f
y
= 60,000 psi
Required fire resistance rating = 2 hours
(1) LOAD DATA
Roof:
LL = 20 psf Floors: LL = 50 psf
DL = 122 psf DL = 136 psf (8.5 in. slab)
Calculations for the first story interior column are as follows:
(a) Total factored load:
*
Factored axial loads due to gravity are summarized in Table 5-5.
Table 5-5 Interior Column Gravity Load Summary for Building #2—Alternate (1)
Tributary
Area
(sq ft)
Floor
Dead
Load
(psf)
Live
Load
(psf)
Influence
Area
RM
Reduced
Live Load
(psf)
Cumulative
Dead Load
(kips)
Cumulative
Live Load
(kips)
Cumulative
Factored
Load
ACI-Eq. (9-2)
(kips)
5th (roof)
122
20
480
—
1
20.0
63
9.6
80
4th
136
50
480
1920
0.59
29.5
132
23.8
186
3rd
136
50
480
3840
0.49
24.5
201
35.5
288
2nd
136
50
480
5760
0.45
22.5
270
46.3
388
1st
136
50
480
7680
0.42
21.0
340
56.4
487
(b) Factored moments:
gravity loads:
The moment due to dead load is small. Only moments due to live loads and wind loads will
be considered.
* Axial load from wind loads is zero (see Fig. 2-15).
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