Engineering Mechanics

Chapter 12 : Support Reactions 241

Now equating the anticlockwise and clockwise moments about A, 22 14 8 89.24 BV cos 30 cos 30 0.866 R ×× ×=+== °° ∴ 9.24 1.15 kN BV 8 R ==

and RAV = (1 sin 60° + 2 sin 60° + 1 sin 60°) – 1.15 kN
= (1 × 0.866 + 2 × 0.866 + 1 × 0.866) – 1.15 = 2.31
∴ Reaction at A,

(1)^22 (2.31) 2.52 kN RA=+ = Ans.

and

2.31 tan 2.31 1

θ=A = or θA = 66.6° Ans.

Similarly, RB=+ =(1)^22 (1.15) 1.52 kN Ans.

and

1.15 tan 1.15 B 1 θ= = or θB = 49° Ans.

EXERCISE 12.2

A truss shown in Fig. 12.36 is subjected to two points loads at B and F.

Fig. 12.36. Find by any method the reactions at A and E. [Ans. RA = 1.8 kN, RE = 3.0 kN, θ = 56.3°]

A truss is subjected to two point loads at A as shown in Fig. 12.37.

Fig. 12.37. Find the reactions at G and H.[Ans. RG = 22.4 kN, RH = 20 kN, θ = 63.4°]