1. Professor Dr. A.Salam Al-Ammri & Suhad Ibraheem Mohammad
ENGINEERS MECHANICS
STATICS
CHAPTER 5
Lecture Notes:
Professor A. Salam Al-Ammri
Suhad Ibraheem Mohammed
Al-Khwarizmi College of Engineering
University of Baghdad
Analysis of Structures Trusses
Method of Joint
2/17/2012
Professor Dr. A.Salam Al-Ammri & Suhad Ibraheem Mohammad

2. Professor Dr. A.Salam Al-Ammri & Suhad Ibraheem Mohammad
Contents
Introduction
Analysis of Trusses by the Method of Joints
Joints Under Special Loading Conditions
Sample Problem 5.2.1
Sample Problem 5.2.2
Sample Problem 5.2.3
2/17/2012
Professor Dr. A.Salam Al-Ammri & Suhad Ibraheem Mohammad

3. Analysis of Trusses by the Method of Joints
2/17/2012
Professor Dr. A.Salam Al-Ammri & Suhad Ibraheem Mohammad

4. Joints Under Special Loading Conditions
Forces in opposite members intersecting in two straight lines at a joint are equal.
The forces in two opposite members are equal when a load is aligned with a third member. The third member force is equal to the load (including zero load).
The forces in two members connected at a joint are equal if the members are aligned and zero otherwise.
2/17/2012
Professor Dr. A.Salam Al-Ammri & Suhad Ibraheem Mohammad

5. Joints Under Special Loading Conditions
2/17/2012
Professor Dr. A.Salam Al-Ammri & Suhad Ibraheem Mohammad

6. Professor Dr. A.Salam Al-Ammri & Suhad Ibraheem Mohammad
Sample Problem 5.2.1
Using the method of joints, determine the force in each member of the truss.
Joint A is subjected to only two unknown member forces.
2/17/2012
Professor Dr. A.Salam Al-Ammri & Suhad Ibraheem Mohammad

7. Professor Dr. A.Salam Al-Ammri & Suhad Ibraheem Mohammad
Sample Problem 5.2.1
Joint D
Joint B
joint E
2/17/2012
Professor Dr. A.Salam Al-Ammri & Suhad Ibraheem Mohammad

8. Professor Dr. A.Salam Al-Ammri & Suhad Ibraheem Mohammad
Sample Problem 5.2.1
All member forces and support reactions are known at joint C. However, the joint equilibrium requirements may be applied to check the results.
2/17/2012
Professor Dr. A.Salam Al-Ammri & Suhad Ibraheem Mohammad

9. Professor Dr. A.Salam Al-Ammri & Suhad Ibraheem Mohammad
Sample Problem 5.2.2
Determine the loads in each of the members by using the method of joints.
Draw the free-body diagram.
Joint B
2/17/2012
Professor Dr. A.Salam Al-Ammri & Suhad Ibraheem Mohammad

10. Professor Dr. A.Salam Al-Ammri & Suhad Ibraheem Mohammad
Sample Problem 5.2.2
Look at Joint D and find the angle
Joint C
2/17/2012
Professor Dr. A.Salam Al-Ammri & Suhad Ibraheem Mohammad

11. Professor Dr. A.Salam Al-Ammri & Suhad Ibraheem Mohammad
Sample Problem 5.2.3
Determine the force in members DB , DC and BC (mention whether they are in T or C), if P1 = 240 lb and P2 = 100 lb .
2/17/2012
Professor Dr. A.Salam Al-Ammri & Suhad Ibraheem Mohammad