Engineering Mechanics

(^312) „„„„„ A Textbook of Engineering Mechanics
Example 14.17. Figure 14.43 shows a pin-jointed frame carrying vertical loads of 1 kN
each at B and G and horizontal load of 4 kN at D.
Fig. 14.43.
Find graphically, or otherwise, force in the various members of the truss. Also prepare a table
stating the nature of forces.
Solution. Since the frame is supported on rollers at the right hand support (E), therefore the
reaction at this support will be vertical (because of horizontal support). The reaction at the left hand
support (A) will be the resultant of vertical and horizontal forces.
Taking moments about A and equating the same,
VE × 8 = (1 × 2) + (1 × 4) + (4 × 4.5) = 24
∴
24
3 kN( ) and 3 – 2 1 kN( )
EA 8
VV== ↑ = = ↓
and HA = 4 kN (←)
First of all, draw the space diagram and name all the members and forces according to Bow’s
notations as shown in Fig. 14.44 (a).
Fig. 14.44.
Now draw the vector diagram as shown in Fig. 14.44 (b). Measuring the various sides of the
vector diagram, the results are tabulated here :