Advanced Methods of Structural Analysis

3.3 Simple Trusses 49

F 1

F (^1) F
2 F 2
Fig. 3.11 A truss with compound members
The analysis of this truss should be performed as if all the compounded mem-
bers are solid rods. The obtained internal forces should be applied to the compound
member and then that member is considered as a truss. Since each compound mem-
ber is subjected to two balanced forces, the reactions of the supports are each zero.
Therefore, the supports of each compound member can be disregarded.

3.2.3 Complex Trusses.............................................

Trusses that are complex use other ways to connect two (or three) rigid discs.
Figure3.12a presents a connection of two rigid discs using hingeH,twobars
1 and 2, and an additional supportC. This connection arrangement produces a
Wichert truss. Figure3.12b presents a connection of three rigid discs using hinge
Cand three hinged end bars 1, 2, and 3.

D 1 D 2

a

b

C

1 2

3

B

C

1 2

H

Fig. 3.12 Complex trusses

3.3 Simple Trusses.........................................................

Construction of influence line for internal forces in trusses is based on analytical
methods used for computing internal forces induced by fixed loads. However, con-
struction of influence line for internal forces in a truss has specific features, which
will be considered while using this method. We direct the reader’s attention to the
next important and fundamental point: as in the case of beams, the construction of