Question

Determine the forces in the following members of the truss: BC, FD, and BJ. Indicate tension or compression. Point F is at the middle of DG. ¥9—+ 4 ft 4 ft - 19—+ 3000 lb 1000 lb 19

Answer 1

to let & be a roller support. Csingle Reaction). finding of zero force members : G] 411 411 x! 30001b 100D Іь Reaction force Calculations : {fx=0 . Ex + Ax = 0 10 [fy-o - Reaction force. ny = 4000lb Ay - 4ovolby EMA=0 - Ex(18) - 3000 €) -1000 (12) -0 > Ex= - 2000 lb 11 9 Realion force Ex. 2000 lb . Ax= 2000 lbf| 3 Reaction fine Ax. 2000b1 By Method of heutione : at section xx'

o [fx=0 Ax-Fic ws (56.30) = 0 fjl= 3604.61161 freebody Diagram - consider lower part.. FBC Fre fil Blog TO Efy:o Tension o Tant (1) 56.80° & EMA-O FBc + fj1 = -4000 42-2006) 1 - 400016 Fir (4) & fic cos( 56.30) (6) & fic sin(56.10) (4) = 0 42=200016 A DIK fjI = -5998.87161 :| Fre = 1998.8616} ] fjIcompression fic - Tension Tension for sution yay Efe - 0 freebody Diagram consider upper body :- D FDF cos (36.86) - foc ws C 56.10) = 2000 10N36.86 ft: -2000lb 56-30 > For FOC for 10 Ify - 0 - for sin (36.86) - foc sin (56.10) - hot = 0 EME=0 - fpc sin(56.10)(4) - Fpp sin (36.86) (4) -0 by solving any two equations FDF = 1666.44 Ibt foc = -1201 551bf Tension compression. WIAI

for BJ :- is a zero force members, " Noload at node B No Reaction at nodeB BC AB are collinear members B o J

FRC = 1998.8616 (7) fro - 1666,4 lb CT) FBI = 0

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