®
B r i d g e S e t
W a r r e n B r i d g e
10
In spanning a particular distance, why wouldn’t you use
the smaller scale bridge and add more panels? An exami-
nation of the forces in the memebers of each size bridge
will give the answer. If the smaller and larger bridges
have the same number of panels and experience the same
load, the forces in any member of the smaller bridge is
the same as the same member in the larger bridge. Each
additional panel is submitted to larger forces. This can be
explored using load cells. See the section on Measure-
ment of Static and Dynamic Loads
Figures 20 through 23 show additional common types of bridges. Investigate how the forces in these bridges dif-
fer from the Warren..
Figure 20: (Top) Pratt. (Bottom) Howe
#4
#5
#3
#3
Figure 21: Free-standing Howe
#5
Cord
#4
#3
#3
#4
#5
#2
#3
Figure 22: Waddell “A” Truss Bridge
Figure 23: Deck Truss Bridge
(Connect the sides with #3 or #4 beams.)