# V. Stress in a 2D Truss Model

Find the joint deflection and member stress due to a joint load in a plane truss.

## Reference

Timoshenko, S., Strength of Materials, Part 1, D. Van Nostrand Co., Inc., 3rd edition, 1956, page 10, problem 2.

## Problem

Determine the vertical deflection at point A and the member stresses

 AX = 0.5 in2

 E = 30E6 psi

 P = 5000 lbf

 L = 180 in.

 angle = 30°

## Comparison

Table 1. Comparison of results
σA (psi) 10,000. 10,000. none
δA (in) 0.12 0.12 none

The file C:\Users\Public\Public Documents\STAAD.Pro CONNECT Edition\Samples\ Verification Models\02 Trusses\Stress in a 2D Truss Model.STD is typically installed with the program.

``````STAAD TRUSS : STRESS IN TRUSS
START JOB INFORMATION
ENGINEER DATE 18-Sep-18
END JOB INFORMATION
*
*  THIS EXAMPLE IS TAKEN FROM 'STRENGTH OF MATERIALS'
*  (PART 1) BY TIMOSHENKO, PAGE 10 PROB 2.
*  THE ANSWER IN THE BOOK , DEFLECTION = 0.12 INCH
*  AND STRESS =10000 PSI
*
UNIT INCHES POUND
JOINT COORDINATES
1 0 0 0; 2 155.885 -90 0; 3 311.769 0 0;
MEMBER INCIDENCES
1 1 2; 2 2 3;
MEMBER PROPERTY AMERICAN
1 2 PRIS AX 0.5
DEFINE MATERIAL START
ISOTROPIC MATERIAL1
E 3e+07
POISSON 0.15
END DEFINE MATERIAL
CONSTANTS
MATERIAL MATERIAL1 ALL
SUPPORTS
1 3 PINNED
2 FY -5000
PERFORM ANALYSIS
PRINT JOINT DISPLACEMENTS
PRINT MEMBER STRESSES
FINISH
``````

```   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    0.00000  -0.12000   0.00000   0.00000   0.00000   0.00000
3    1    0.00000   0.00000   0.00000   0.00000   0.00000   0.00000
************** END OF LATEST ANALYSIS RESULT **************
32. PRINT MEMBER STRESSES
MEMBER   STRESSES
: STRESS IN TRUSS                                        -- PAGE NO.    4
MEMBER STRESSES
---------------
ALL UNITS ARE POUN/SQ INCH
MEMB   LD  SECT    AXIAL    BEND-Y     BEND-Z   COMBINED  SHEAR-Y  SHEAR-Z
1    1   .0  10000.0 T      0.0       0.0   10000.0      0.0      0.0
1.0  10000.0 T      0.0       0.0   10000.0      0.0      0.0
2    1   .0  10000.0 T      0.0       0.0   10000.0      0.0      0.0
1.0  10000.0 T      0.0       0.0   10000.0      0.0      0.0
```