Question

Statics

4- For the truss shown below a-The truss shown is externally circle correct answer) (2 point) a) determinate and unstable b) indeterminate and stable c) determinate and stable d) indeterminate and unstable Reason: (3 point) b- The truss shown is internally (circle correct answer) (2 point) a) determinate and unstable b) indeterminate and stable c) determinate and stable d) indeterminate and unstable Reason: (3 point) - Place an "O" on members with zero force on the truss (5 points) d-Solve for internal force in member (5 points) CD- (5 points) DH (5 points) BI- 20 K 60 KJ 20 ft B D 25 K 4 @ 20 ft-80 ft

Answer 1

띨 T 20k De GOK J H G F 2 o 2oft. 0 CH Ax An B e E 20 ft 28 ft. 2oft. 20ft. 25K HOTE 3 Total members (m) = 17 and all the reactions are not concurrent or e parallel. Total reactions (*) Therefore the truss is Total Joints Externally Stable and ..(m+r) = 24 Statically determinate truss. = 10 moment about A. -- EMA=0. Taking Ey Ey X80 - 20 X60525x40-60X20=0 42.5K = 20 +25 ' I Fy + Ey =) Ay = 2.5K GOK J I fyI E Fx =O; -'. Ax = 60k. Ay = 45-42-5 - Ay Taking moment about A. -- EMA=0; -- (FHI + Fez)X20 + 60x200 = Frt for - 60 As AM Efy=0; :- Ay FBI = 2.5K FBI = 2.5k atsil 20 ft FAB 20ft. B 'Ay SECTION-I

20K 8= 45° Taking moment about 'D! H VG GH FDH N o Fed E D Ey - EMo =0; .. Ey x20 X20 + F.,X20 =0 5) FG =- Ey =6) 42-5K :. Et = 6-) 42-5K E Fx=0; 20ft :: FD + Fo Cose + FH = 0 SECTION-II oslo => ep + Fox Cos 45º = 42.5 2. Efyao; Ey + FDH Sino - 2020 => 42.5 + For Sin45°-20 = 0 lm letal For = CE) 31-82 K Ep - 31.82 xC0845°= 42.5 sitor that .(ل) From equation, FED = 65K © zero force members are as follows. put =0 "AJ =0 FEF FFG =0 b I'm tr=27 and All the reactions are not Concurrent or parallel. The truss is Externally stable and determinate truss, and by inspection the truss is internally stable. . This truss is inter internally determinate and stable truss.