4., is subjected to an (e Poe vertical load of 12 KN at A as shown. Determine: E 2 1m
(a)  forces in members AB & AF, using the ‘ Method of Joints, with the aid of free body F am diagram of the relevant joint, and “

(b} the forces in members BC & EF, using the A : G: M Method of Sections, with the aid of free body 12 kN 5 iCk diagram of the relevant section. He BN peg Mn peg lM, A pin-jointed truss frame ABCDEF, supported by D smooth rollers at C and hinged at D
(c) Identify the zero-force member(s), if any, without doing any calculation. [Ans: – 24 KN (C), 26.83 KN (T), – 24 KN (C), 26.83 KN (T)]

5. The truss frame hinged at A and supported by a roller at G, is 180 KN D subjected to a force of 150 KN at D, and 60 KN at F as shown. Determine: 3m
(a) the forces in members CD & DE, using the Method of Joints, with the aid of a free body diagram of the relevant 3m 60 kN, joint, and X B Ee 30°
(b} the forces in members AB & AF, using the Method of Sections, with the aid of a free-body diagram of the 3m relevant section.

8. A pin-jointed truss is hinged at G and supported at A by frictionless rollers on a vertical plane as shown. External forces of 15 kN, 20 KN, and 25 kN are applied at joints B, C, and H respectively.
Determine:

(a) the reactions at the supports, with the aid of free body diagram of the entire truss,
(b) the forces in members EF, FI & HI, using the Method of Sections, with the aid of a free body diagram of the relevant section, and
(c) the forces in members FG & GH, using the Method of Joints, with the aid of a free body diagram of the relevant joint.
(d) Identify the zero-force member(s), if any, without doing any calculation.

[Ans: 35.5 kKN(>), 26.95 kN(<—), 58.49 KN(T), – 11.63 KN (C), – 44.38 KN (C), 3.26 KN (T), – 38.28 kN (C), – 33.69 KN