Engineering Mechanics

Chapter 14 : Analysis of Perfect Frames (Graphical Method) „„„„„ 299

Example 14.7. A framed structure of 6 m span is carrying a central point load of 10 kN as
shown in Fig 14.15.

Fig. 14.15.
Find by any method the magnitude and nature of forces in all members of the sturcture.
*Solution. Since the structure is symmetrical in geometry and loading, therefore the reaction
at A,

10

5kN

AB 2

RR===

First of all, draw the space diagram and name the members and forces according to Bow’s
notations as shown in Fig. 14.16 (a).

Fig. 14.16.
Now draw the vector diagarm as shown in Fig. 14.16 (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 AC, CB 11.2 Compression

2 AD, DB 7.1 Tension

3 CD 10.0 Tension

* We have already solved this example analytically in the last chapter.