4. A pin-jointed truss frame ABCDEF, supported by D smooth rollers at C and hinged at D, is subjected to a (e poe vertical load of 12 KN at A as shown. Determine: E 2 1m
(a) the 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,

(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 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 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 free body diagram of the 3m relevant section. ¥nf@) (e)G 7. SP

(c) Identify the zero-force_ member(s), if any, without doing Aron LM smog
any calculation. ‘
[Ans: 225 KN (T), – 270.42 kN (C), 225 KN (T), – 59.97 KN (C)]