Steel truss bridges - Computational Analysis and Design of Bridge Structures - page 314

30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

8030′ 7½″ 245′ 0″ Parallel to grade

Suspended span Cantilever arm Anchor span Cantilever arm

Figure 10.18 Configuration of Tydings Bridge, Maryland.

−10°F (−23.3°C) to 120°F (48.9°C), and also it employs a combination of
riveted as well as bolted connections.
The 13-span, 1540-m (5051′) structure possesses a deck width of
26.6 m (87′-4″), with 11.9 m (39′-0″) of roadway width in each direction.
The bridge uses two parallel truss structures, spaced at 13.7 m (45′-0″),
center to center and each consisting of three unique truss panel arrange-
ments as shown in Figure 10.18 with the combination of a suspended span
and an anchor span with two cantilever arms. Each of the six suspended
spans consist of eight truss panels spaced at 9.3 m (30′-7 1/2″), providing
a total length of 74.7 m (245′). Five anchored spans of seven panels for
a total length of 65.3 m (214′-4 1/2″) for the center span and 10 canti-
levered arms with four panels make up the 37.3-m (122′-6″) span. The
entire bridge consists of these two types in a repetitive fashion, essentially
permitting one to analyze the entire structure with a simplified approach.
The bridge also uses 13 piers, with piers 2 and 13 supporting the end of
the truss suspension spans and thus carrying identical loads, whereas
piers 3 through 12 support equal load. All members are built-up plate
sections constructed with one of two possible materials: high-strength
low alloy structural steel or the typical structural carbon steel. For anal-
ysis purposes, specific section properties, such as member area, yield
stress, and radius of gyration, are of vital importance to ensure accuracy
throughout the analysis and were obtained from the original construc-
tion documents.
Supported by the trusses, the bridge is comprised of just over 300
floor beams of three unique types. The beams are designated as F1, F2,
and F3. Beams F1 and F3 are plate girders with (1) 1524 mm × 8 mm
(60″ × 5/16″) web, (2) 356 mm × 19 mm × 17 m (14″ × 3/4″ × 56′) cover
plates, and (3) 200 mm × 150 mm × 17 mm (8″ × 6″ × 3/4″) angles.
F2 beams are composed of (1) 1524 mm × 8 mm (60″ × 5/16″) web,
(2) 325 mm × 13 mm × 17.3 m (13″ × 1/2″ × 56′-10½″) cover plates, and
(3) 150 mm × 150 mm × 14 mm (6″ × 6″ × 9/16″) angles. F3 beams can
be seen at all floorbreaks, whereas F2 beams are located at each expan-
sion joint, and F1 beams are at all the remaining panel point locations.
Carried by the floor beams, seven different stringers were used. Designated
A through G, each stringer spans between the floor beams, stiffening the