1. Truss Calculations with MD Solids

2. Trusses
Enter the information into MD Solids. Before you press “Compute” , try to predict which members are in compression and which are in tension.*
*If necessary, refer to the wide variety of “MD Solids Help Documents” included in the MD Solids software to help you get started.

3. Trusses
Notice the gold colored members labeled with a (C) are in compression, and the blue colored members labeled with a (T) are in tension. Did you guess correctly?

4. Trusses
Try to predict which members here are in tension and which are in compression.

5. Trusses
The members in purple are in neither tension or compression. Sometimes, additional members do not help to support a load. These are called zero-force members.

6. Trusses
Try to predict which members here are in tension and which are in compression.

7. Trusses
Compare your predictions with the solution.

8. Trusses

9. Trusses

10. Trusses
Solve for the force in each member of the truss in this example to find whether the members are in tension or compression. Use MD Solids software.
Start by replacing the supports with reaction forces: A C 3m 4m D B
300 N
200 N

11. Trusses Here the supports have been replaced with reaction forces: 4mCY
300 N
200 N 3m CX AY

12. This is how the problem looks when entered into MD Solids.
Trusses
This is how the problem looks when entered into MD Solids.

13. The solution shows forces in each member and at each support.
Trusses
The solution shows forces in each member and at each support.

14. Trusses For of the following trusses:
Replace the supports with the appropriate reaction forces.
Predict which beams would be in tension, which would be in compression, and which would be supporting the most force.
Draw the truss in MD Solids.
Record the forces at the supports and in each beam.
Were your predictions correct?

15. Trusses #1 •
3 ft
4 ft
60 lbs
80 lbs
• •
• • •
2 ft
500 lb #2

16. Trusses 200 N 5 kN* 7 kN* 3 m 4 m #3 2 m 3 m 3m #4
• • •
• •
3 m
5 kN*
4 m
7 kN* #3
2 m
• • •
3 m 3m
200 N
• • #4
* 1 KN = 1000N, therefore 5kN = 5000N

17. Trusses
Solution for #1

18. Trusses
Solution for #1

19. Trusses
Solution for #2

20. Trusses
Solution for #2

21. Trusses
Solution for #3

22. Trusses
Solution for #3

23. Trusses
Solution for #4

24. Trusses
Solution for #4