G-04 (Axial-Flexural Design of Concrete Slender Columns) |
  
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G-04 (Axial-Flexural Design of Concrete Slender Columns) |
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Objective
To verify the axial-flexural design of the rectangular concrete column (braced)
Problem Description
The following concrete braced column [Ref 1] is to be designed according to ACI 318-02 code. The clear concrete cover to stirrup is 1.5 inches. Use fc = 4 ksi, fy = 60 ksi
Size (in) |
18 x 18 |
Total length (ft) |
13 |
Unbraced length (ft) |
13 |
Effective length factor |
0.87 |
Dead Pu (kips) |
230 (compression) |
Dead Mu-top (ft-kips) |
2 |
Dead Mu-bottom (ft-kips) |
-2 |
Live Pu (kips) |
173 (compression) |
Live Mu-top (ft-kips) |
108 |
Live Mu-bottom (ft-kips) |
100 |
Finite Element Model
1 beam elements with appropriate material and design criteria assigned
Model type: 2D Frame
Results
The following table shows some intermediate and final results during the design. The program gives comparable results with the reference [Ref 1].
|
ENERCALC 3D |
[Ref 1] |
Cm |
0.960 |
0.96 |
βd. |
0.499 |
0.50 |
Moment magnification factor |
1.145 |
1.15 |
Pu (kips) |
552.8 |
553 |
Mu (ft-kips) |
200.6 |
201 |
Bars |
8 # 9 |
4 # 10 + 4 # 9 |
Comments
Since this is a braced column, we do not need to perform the 2nd order analysis for the design.
Reference
[1]. Arthur H. Nilson, David Darwin, Charles W. Dolan, “Design of Concrete Structures”, 13th Edition, pp. 304, McGraw-Hill Higher Education, 2004
