V. ACI 318-11 Square Column
Calculate the axial capacity of a square column subjected to an axial compressive force, given Ast
Details
A square, cantilever column of length 5ft with an ultimate axial load of 998 kip has the following concrete and steel properties.
- Compressive strength of concrete (normal weight concrete), fc = 5,000 psi
- Yield strength of steel, fy = 60,000 psi
- Clear spacing for outermost bottom reinforcement to bottom face, Cc = 1.5 in
- Width of column, B = 20 in
- Depth of column, D = 20 in
- Strength reduction factor, ϕ = 0.65
- Number of #9 bars = 4
- Rebar diameter for #9 bar, Ød = 1.128 in
Factored axial load (axial demand), Pu = 998 kip
Results
Parameter | Hand Calculation | STAAD.Pro | Difference | Comments |
---|---|---|---|---|
P0 (kip) | 1,923 | 1,923 | none | |
Pn (kip) | 1,583 | 1,583.4 | negligible | |
Bar configuration | 4- #9 bars | 4- #9 bars | none | |
Column size | 20"×20" tied column | 20"×20" 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 Square Column.STD is typically installed with the program.
STAAD SPACE
START JOB INFORMATION
***********************************************************************
* This example is a replica of example no 6.3 of PCA Notes 318-11.
***********************************************************************
ENGINEER DATE 21-June-2020
JOB NAME PCA Example 6.3
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 6 0;
MEMBER INCIDENCES
1 1 2;
UNIT INCHES KIP
DEFINE MATERIAL START
ISOTROPIC CONCRETE
E 3150
POISSON 0.17
DENSITY 8.68e-05
ALPHA 5.5e-06
DAMP 0.05
TYPE CONCRETE
STRENGTH FCU 4
END DEFINE MATERIAL
MEMBER PROPERTY AMERICAN
1 PRIS YD 20 ZD 20
CONSTANTS
MATERIAL CONCRETE ALL
UNIT FEET KIP
SUPPORTS
1 FIXED
UNIT INCHES KIP
LOAD 1 LOADTYPE None TITLE LOAD CASE 1
JOINT LOAD
2 FY -998
PERFORM ANALYSIS
START CONCRETE DESIGN
CODE ACI 2011
FC 5 ALL
MXMT 9 ALL
MXMB 9 ALL
MXMS 9 ALL
MIMT 9 ALL
MIMB 9 ALL
MIMS 9 ALL
TRACK 2 ALL
DESIGN COLUMN 1
END CONCRETE DESIGN
FINISH
STAAD Output
ACI 318-11 COLUMN NO. 1 DESIGN RESULTS
===============================================
FY - 60000 FC - 5000 PSI, SQRE SIZE - 20.00 X 20.00 INCHES, TIED
ONLY MINIMUM STEEL IS REQUIRED.
AREA OF STEEL REQUIRED = 4.000 SQ. IN.
BAR CONFIGURATION REINF PCT. LOAD LOCATION PHI-Z PHI-Y
-------------------------------------------------------------------
4 - NUMBER 9 1.000 1 END 0.000 0.000
(PROVIDE EQUAL NUMBER OF BARS ON EACH FACE)
TIE BAR NUMBER 9 SPACING 18.05 IN
COLUMN INTERACTION: MOMENT ABOUT Z -AXIS (KIP-FT)
--------------------------------------------------------
P0 Pn max P-bal. M-bal. e-bal.(inch)
1923.00 1538.40 716.26 446.51 7.48
M0 P-tens. Des.Pn Des.Mn e/h
156.73 -240.00 Infinity NaN 0.00000
--------------------------------------------------------
COLUMN INTERACTION: MOMENT ABOUT Y -AXIS (KIP-FT)
--------------------------------------------------------
P0 Pn max P-bal. M-bal. e-bal.(inch)
1923.00 1538.40 716.26 446.51 7.48
M0 P-tens. Des.Pn Des.Mn e/h
156.73 -240.00 Infinity NaN 0.00000
--------------------------------------------------------
Pn Mn Pn Mn (@ Z )
| 1420.06 279.88 710.03 446.27
P0 |* 1301.72 332.82 591.69 436.82
| * 1183.38 372.72 473.35 420.15
Pn,max|__* 1065.05 403.75 355.02 373.59
| * 946.71 425.39 236.68 309.55
Pn | * 828.37 438.88 118.34 236.06
NOMINAL| * Pn Mn Pn Mn (@ Y )
AXIAL| * 1420.06 279.88 710.03 446.27
COMPRESSION| * 1301.72 332.82 591.69 436.82
Pb|-------*Mb 1183.38 372.72 473.35 420.15
| * 1065.05 403.75 355.02 373.59
___________|____*_______ 946.71 425.39 236.68 309.55
| * M0 Mn, 828.37 438.88 118.34 236.06
| * BENDING
P-tens|* MOMENT
|
********************END OF COLUMN DESIGN RESULTS********************