Question 9.1.1: Identify each system in Figure 1 as either a truss or frame....
IDENTIFY SYSTEMS AS TRUSSES OR FRAMES
Identify each system in Figure 1 as either a truss or frame. Justify your answer.
System 1 (Figure 1a) The system is a truss. Assuming we ignore their weights, all of the members are two-force members because they are all connected by pins and the forces are applied at the pins.
(Question: How could we include member weights and still do a truss analysis?)
System 2 (Figure 1b) The system is a frame because it has at least one multiforce member (the member from which the weight is hanging (Question: based on inspection, will the vertical member carry any load?)
System 3 (Figure 1c) The system is a truss. If we ignore the weights of the members, they are all two-force members.
System 4 (Figure 1d) The system is a frame because DE is a multiforce member. All other members are two-force members if their weights are negligible. Notice that portions of the system are trusses (ACD and BEG form trusses). (Question: Is there anything “odd” about the number of boundary conditions associated with this frame?
We will have a lot more to say about this in the final section of this chapter.)