Question

Problem 4. (25%) The truss shown in the figure is supported by a pin at H and a roller at A. Use method of sections to determine the force in members DF, FE and EG of the truss. State if they are in tension or compression. You must include a FBD. 500 16 200 16 400 16 D 500 16 B F 2 ft 4 in. 200 16 6 ft E G Н. 6-8 -8 ft-t8f-8 ft-7-8 ft-

Answer 1

Hy FBD:- 5ools Х 400 lb 200.1 2.333ft F В. 500.us 6ft i 2001 As son А sft 8 ft i8ft 8ft. B G E Hae Ay O = tan'(2'333) 0-16:26° Take moment about point Hi- EMH =O (2+) x= tant 6 8 36.87 B = tant -400 X8 Soo x16 - 36.87 200 X 24 SOOX.32 +Ay 32 30 Ay= 1000 lb. Efyzo (9+) - 500 - 200- 500 - 400 – 200 tay + Hy = CO Hy = 800 lb EFX=0 (++) Hazo.

* consider the section. *-* passing through DF, EF, EG tonsi Take moment about point F:- EME ZO Cht) RDF 400 lb (RGE *6.)-(H4 x 8) +200% 8) =0 F RGE = 800 lb. (T) 2oollo. REF 6ft. > Ha G eft Efyzo (9+) H RGE Hy - 400 – 200 + 800 REFX sin (36:87) + RDF X (16:26) =0 200 - REF xsin (3687) + RDF x (16.26) = 0 - (1) EF2=0 (7+). - - 800 ROF x cos(16:26) - REF X COS (36:87) = 0; By solving equation (10 3C2), we get REF =-40 llo REF - 40 lb (c) RDF = -8.00 ls. R, -DF 800 lb (c)