V. Deflections in a 2D Truss Model
Find the joint deflection due to joint loads in a plane truss.
Reference
McCormac, J. C., Structural Analysis, Intext Educational Publishers, 3rd edition, 1975, page 271, example 18 - 2.
Problem
Determine the vertical deflection at point 5 of plane truss structure shown in the figure.
P = 20 kip
L = 15 ft
Truss width = 4 spaces at 15 ft = 60 ft
Truss height = 15 ft
AX 1-4 = 1 in2, AX 5-6 = 2 in2, AX 7-8 =1.5 in2, |
AX 9-11 B = 3 in2 P, AX 12-13 = 4 in2 |
E = 30E3 ksi |
STAAD Input
The file C:\Users\Public\Public Documents\STAAD.Pro CONNECT Edition\Samples\ Verification Models\02 Trusses\Deflections in a 2D Truss Model.STD is typically installed with the program.
STAAD TRUSS : DEFLECTION IN TRUSS
START JOB INFORMATION
ENGINEER DATE 18-Sep-18
END JOB INFORMATION
*
* REFERENCE 'STRUCTURAL ANALYSIS' BY JACK McCORMACK, PAGE
* 271 EXAMPLE 18-2. ANSWER - Y-DISP AT JOINT 5 = 2.63 INCH
*
UNIT FEET KIP
JOINT COORDINATES
1 0 0 0; 2 15 0 0; 3 30 0 0; 4 45 0 0; 5 60 0 0; 6 15 7.5 0; 7 30 15 0;
8 45 7.5 0;
MEMBER INCIDENCES
1 2 6; 2 3 4; 3 4 8; 4 4 5; 5 1 2; 6 2 3; 7 3 6; 8 3 8; 9 3 7; 10 1 6;
11 5 8; 12 6 7; 13 7 8;
UNIT INCHES KIP
MEMBER PROPERTY AMERICAN
1 TO 4 PRIS AX 1
5 6 PRIS AX 2
7 8 PRIS AX 1.5
9 TO 11 PRIS AX 3
12 13 PRIS AX 4
DEFINE MATERIAL START
ISOTROPIC MATERIAL1
E 30000
POISSON 0.3
END DEFINE MATERIAL
CONSTANTS
MATERIAL MATERIAL1 ALL
SUPPORTS
1 PINNED
3 FIXED BUT FX MZ
LOAD 1 VERTICAL LOAD
JOINT LOAD
2 4 5 FY -20
PERFORM ANALYSIS
PRINT JOINT DISPLACEMENTS
FINISH
STAAD Output
JOINT DISPLACEMENT (INCH RADIANS) STRUCTURE TYPE = TRUSS ------------------ JOINT LOAD X-TRANS Y-TRANS Z-TRANS X-ROTAN Y-ROTAN Z-ROTAN 1 1 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 2 1 -0.12000 0.18000 0.00000 0.00000 0.00000 0.00000 3 1 -0.24000 0.00000 0.00000 0.00000 0.00000 0.00000 4 1 -0.48000 -0.89516 0.00000 0.00000 0.00000 0.00000 5 1 -0.72000 -2.63033 0.00000 0.00000 0.00000 0.00000 6 1 -0.00820 0.24000 0.00000 0.00000 0.00000 0.00000 7 1 0.29758 -0.12000 0.00000 0.00000 0.00000 0.00000 8 1 0.06578 -0.83516 0.00000 0.00000 0.00000 0.00000