V. ACI 318-11 Circular Column
Calculate the axial capacity of a circular column subjected to axial compressive force, given Ast
References
ACI 318-11
Details
A circular, cantilever column of length 5ft with an ultimate axial load of 500 kip has the following concrete and steel properties.
- Compressive strength of concrete (normal weight concrete), fc = 4,000 psi
- Yield strength of steel, fy = 60,000 psi
- Clear spacing for outermost bottom reinforcement to bottom face, Cc = 1.5 in
- Diameter of column, D = 20 in
- Strength reduction factor, ϕ = 0.65
- Number of #8 bars, N = 6
- Rebar diameter for #8 bar, d = 1 in
Factored axial load (axial demand), Pu = 500 kip
Results
Parameter | Hand Calculation | STAAD.Pro | Difference | Comments |
---|---|---|---|---|
P0 (kip) | 1,335 | 1,336.43 | negligible | |
Pn (kip) | 1,068 | 1,069.14 | negligible | |
Bar configuration | 6- #8 bars | 6- #8 bars | none | |
Column size | 20" dia. tied column | 20" dia. tied column | none |
STAAD Input
The file C:\Users\Public\Public Documents\STAAD.Pro 2024\Samples \Verification Models\10 Concrete Design\US\ACI 318-11 Circular Column.STD is typically installed with the program.
STAAD SPACE
START JOB INFORMATION
ENGINEER DATE 15-May-2020
ENGINEER NAME Design of Circular Column
JOB CLIENT Bentley Systems Inc.
ENGINEER NAME TK
END JOB INFORMATION
INPUT WIDTH 79
UNIT FEET KIP
JOINT COORDINATES
1 0 0 0; 2 0 5 0;
MEMBER INCIDENCES
1 1 2;
DEFINE MATERIAL START
ISOTROPIC CONCRETE
E 453600
POISSON 0.17
DENSITY 0.14999
ALPHA 5.5e-06
DAMP 0.05
TYPE CONCRETE
STRENGTH FCU 576
END DEFINE MATERIAL
MEMBER PROPERTY AMERICAN
1 PRIS YD 1.66667
CONSTANTS
MATERIAL CONCRETE ALL
SUPPORTS
1 FIXED
LOAD 1 LOADTYPE Dead TITLE LOAD CASE 1
JOINT LOAD
2 FY -500
PERFORM ANALYSIS
SECTION 0 0.25 0.5 0.75 1 ALL
PRINT SUPPORT REACTION ALL
START CONCRETE DESIGN
CODE ACI 2011
MAXMAIN 8 ALL
MINMAIN 8 ALL
TRACK 2 ALL
DESIGN COLUMN ALL
END CONCRETE DESIGN
FINISH
STAAD Output
ACI 318-11 COLUMN NO. 1 DESIGN RESULTS
===============================================
FY - 60000 FC - 4000 PSI, CIRC SIZE 20.00 INCHES DIAMETER TIED
ONLY MINIMUM STEEL IS REQUIRED.
AREA OF STEEL REQUIRED = 3.142 SQ. IN.
BAR CONFIGURATION REINF PCT. LOAD LOCATION PHI
----------------------------------------------------------
6 - NUMBER 8 1.509 1 END 0.650
(EQUALLY SPACED)
TIE BAR NUMBER 4 SPACING 16.00 IN
COLUMN INTERACTION: MOMENT ABOUT Z/Y -AXIS (KIP-FT)
--------------------------------------------------------
P0 Pn max P-bal. M-bal. e-bal.(inch)
1336.43 1069.14 475.51 247.89 6.26
M0 P-tens. Des.Pn Des.Mn e/h
153.92 -284.40 769.23 0.00 0.00000
--------------------------------------------------------
Pn Mn Pn Mn
| 986.90 144.54 493.45 246.76
P0 |* 904.66 176.00 411.21 248.11
| * 822.42 201.19 328.97 246.46
Pn,max|__* 740.18 220.34 246.73 239.25
| * 657.93 233.38 164.48 222.95
Pn | * 575.69 242.15 82.24 190.02
NOMINAL| *
AXIAL| *
COMPRESSION| *
Pb|-------*Mb
| *
___________|____*_______
| * M0 Mn,
| * BENDING
P-tens|* MOMENT
|
********************END OF COLUMN DESIGN RESULTS********************