Question

60 E pin O roller 9. [1pt] Two forces are applied to the truss as shown, Fi = 128 N and F2 = 164 N. The truss is supported by a pin joint at A and a roller at E. Assume L = 1.30 m. Indicate whether the member AD is in compression (C) or in tension (T). You only have I try! Answer: Submit All Answers 10. [1pt] Calculate the value of the force in member CD. Enter a negative value if the member is in compression. Answer: Submit All Answers 11. [1pt] Calculate the value of the force in member AE. Enter a negative value if the member is in compression. Answer: Submit All Answers 12. [1pt] Calculate the value of the force in member BC. Enter a negative value if the member is in compression. Answer: Submit All Answers

Answer 1

The FBD of given truss is shown below reflecting the reactions at A and E.

F 2 1.3 m В F 1 1.3 m 60 A Ex |Ey Ay

The support reactions are calculated using equilibrium equations as shown below.

↺∑ME=0

F2(2.6)+F1(1.3)−Ay(2.6tan60) = 0

164(2.6)+128(1.3)−Ay(2.6tan60)=0

Ay=131.6N

↑∑Fy=0

Ay+Ey = 0

311.77 +Ey =0

Ey=−131.6N

→∑Fx=0

−Ex−F1−F2=0

−Ex−128−164=0

Ex=−292N

Analysis of joint can be now be done. Begin with joint C. The FBD is shown below. Member forces are assumed to be tensile.

30% F 2 FCD FBC

Free Body Diagram

The force on member CD is obtained by summing forces along x-axis.

→∑Fx=0

FCDsin30−F2=0

FCDsin30−164=0

FCD = 328N,Tension

Summing forces along y-axis will then give the force on member BC.

↑∑Fy=0

−FBC−FCDcos30=0

−FBC−(328)cos30=0

FBC=−284

FBC= 284 N, Compression

FDE 60 Ex Pin Ey FAE

Free Body Diagram

Summing forces along y-axis:

↑∑Fy=0

FDEsin60+Ey=0

FDEsin60+(−131.6)=0

FDE=152N,Tension

Summing forces along x-axis:

→∑Fx=0

−FAE−Ex−FDEcos60=0

−FAE−(−292)−152cos60=0

FAE=216N,Tension