Steel truss bridges - Computational Analysis and Design of Bridge Structures - page 308

(a)

L12L13

0.8
0.6
0.4
0.2

0.0

−0.2

−0.4 0

50 100 150 200 250 300 350 400 450 500 550 600 650 700

(b) x -coordinate

L11U12

1.0
0.5

0.0

0 50 100 150 200 250 300 350 400 450 500 550 600 650 700

−0.5
−1.0

(c) x -coordinate

Figure 10.11 Influence lines of a truss bridge. (a) Main span with two cantilever arms.
(b)Influencelinesampleofatopchord.(c)Influencelinesampleofadiagonal
member.

Mueller-Bresslau principle as adopted in many customized bridge software.
Two influence line samples of a top chord and a diagonal member are
shown in Figure 10.11b and c, respectively.

10.4 3d IlluStrated exaMPle— PedeStrIan
Pony truSS BrIdge

The pony truss bridge as shown in Figures 10.12 and 10.13 has been
considered for the case study. It is a pedestrian steel truss bridge with
57.6 m (189′) length, 4.0 m (13′) height, and 28 panels, located in New
York suburban area. The sections used in this truss bridge are shown in
Table 10.1.
A 3D model is developed using STAAD.Pro as shown in Figure 10.14
where truss elements are used for truss and bracing members, beam ele-
ments are used for floor beams and stringers, and plate elements are used
for the deck. The bridge is considered fixed in all three directions at one end
supports and x (longitudinal) direction released at another end supports.
Shadow area shows a 127-mm (5″) thick concrete deck (Figure 10.13).
Loads based on AASHTO LRFD (U.S.) code are used in this study. The
self-weight of every active element is calculated and applied as a uniformly