Question

9. For the truss shown, determine the magnitude of the force in each member using the method of joints and indicate whether it is in tension (T) or in compression (C). Note the reactions at supports A & B are given. (10) P= 120 36+ P=60 B 344 HA = 60 BB-82.5 BA=37.5 4ft 4f+

Answer 1

p = 120 D 3 ft P=60 J36.87 36.87 B E 153.13 3.ft 个 HA=60 RB = = 82.5 RA= 37.5 * 4ft 4 ft Method of joint At point A E fy=0 RA+ FAL+ FAE C3 53.13 = 0 - 0 E Fx-o FAE Sin 53:13 - 600 / FAE = 75 (1) From @ FAC --82.5 (C) At point B FBD sin 36.87 + RB = 0 , FBD - -137.5 (0)

FBD 13 36.87 + FBE ฟ > F BE = 110 (1) At pointe FLD 336.87 +FCE +60=0 (2) Efy co Fcosin 36.87 + FAC=0 w FCD sin 36.87 +82.5=0 FCD = - 137.5 (C) From (2 FCE E 50 (1) At point FEA sin 36.87 - FED w CFAE : 75 (T) W, FED = 45 (T) FEA i. FAE - 75 (T) FAC = 82.5 (c) FBO = 137.5 (1) FBE - I10 (1) FCD = 137.5 (c) FCE = 50 (7) FED = 45 (1)