Engineering Mechanics

Chapter 14 : Analysis of Perfect Frames (Graphical Method) „„„„„ 297

First of all, draw the space diagram and name all the members and forces according to Bow’s
notations as shown in Fig. 14.12 (a).

Fig. 14.12.
Now draw the vector diagram as shown in Fig. 14.12 (b). Measuring the various sides of the
vector diagram, the results are tabulated here :

S. No. Member Magnitude of force in kN Nature of force

1 1-2 (AG) 5.5 Compression

2 2-3 (BI) 7.0 Compression

3 3-4 (CJ) 7.0 Compression

4 4-5 (DL) 4.5 Compression

5 1-6 (FG) 7.8 Tension

6 2-6 (GH) 2.5 Compression

7 6-7 (EH) 5.5 Tension

8 2-7 (HI) 2.1 Tension

9 3-7 (IJ) 4.0 Compression

10 4-7 (JK) 3.5 Tension

11 7-8 (EK) 4.5 Tension

12 4-8 (KL) 4.5 Compression

13 5-8 (EL) 6.4 Tension

Example 14.6. Find graphically or otherwise, the magnitude and nature of the forces in the
truss shown in Fig. 14.13.

Fig. 14.13.

Also Indicate the results in a tabular form.