Objective:
To calculate the support forces at the base of a column by using P-DELTA Analysis. Only the Large Delta effect is considered.
Input Parameters:
Length of column = 12 ft = 144 in
E=29000 ksi
Section= W8X10
Lateral load= 5 kip
Vertical load= 3 kip
Calculation:
Mz at column base = H x L + P x ∆
where H = the lateral load
L = the length of column
P = the axial compression load and
∆ = the displacement due to the lateral load at the free end of the column.
= 5.5717”
Mz = 5*144 + 3*5.5717
= 736.715 kip-in
STAAD Input file:
STAAD SPACE
START JOB INFORMATION
ENGINEER DATE 22-Sept-13
END JOB INFORMATION
INPUT WIDTH 79
UNIT FEET KIP
JOINT COORDINATES
1 0 0 0; 2 0 12 0;
MEMBER INCIDENCES
1 1 2;
DEFINE MATERIAL START
ISOTROPIC STEEL
E 4.176e+006
POISSON 0.3
DENSITY 0.489024
ALPHA 6.5e-006
DAMP 0.03
END DEFINE MATERIAL
set shear
MEMBER PROPERTY AMERICAN
1 TABLE ST W8X10
CONSTANTS
MATERIAL STEEL ALL
SUPPORTS
1 FIXED
PRINT MEMBER PROPERTIES ALL
LOAD 1 LOADTYPE None TITLE LOAD CASE 1
JOINT LOAD
2 FX 5
LOAD 2 LOADTYPE None TITLE LOAD CASE 1
JOINT LOAD
2 FY -3
PERFORM ANALYSIS PRINT STATICS CHECK
CHANGE
LOAD 3 LOADTYPE None VERTICAL
REPEAT LOAD
1 1.0 2 1.0
PDELTA ANALYSIS LARGEDELTA PRINT STATICS CHECK
unit kips inches
PRINT JOINT DISPLACEMENTS ALL
PRINT MEMBER FORCES
FINISH
Member End force output:
Solution Comparison:
| Solution type | Mz at column base (Kip-in) |
| STAAD.Pro | 736.715 |
| Hand calculation | 736.715 |