Introduction - Computational Analysis and Design of Bridge Structures - page 6

Figure 1.4 The longest span bridge: Akashi Kaikyo Bridge, Japan. (Courtesy of Yokogawa
Bridge Corporation.)
created a workable and efficient method of erecting bridges in a manner
that was both consistent and manageable (Tonias 1994). However, with the
progress of computational methods and computer tools, more refined and
sophisticated methods of analyses have become more common nowadays.
1.2 BrIdge types and desIgn process
Even though fiber-reinforced polymer (FRP) composites have gradually
come to play some roles in civil infrastructures, concrete and steel are still
the main materials for bridges. Concrete and steel can form different shapes
and build different structural types. According to the U.S. National Bridge
Inventory (NBI), as of 2012, the United States has 607,379 highway bridges
where 403,072 bridges (72.12%) are slab-, beam-, or frame-type bridges,
10,649 (1.75%) are truss-type bridges, and 7125 (1.17%) are arch-type
bridges. Only 45 (0.01%) are stayed-girder bridges and 96 (0.02%) are sus-
pension bridges. Another unique type of bridge popular in the coastal area
is the moveable bridge. The moveable bridges are lift-, bascule-, or swing
type, and there are 840 (0.14%) of these types of bridges in the United States.
The average age of a U.S. highway bridge is about 43 years old, whereas the
average age of the 76,000 + U.S. railroad bridges is much older.
For new bridge construction, there are four basic stages for the design
process: conceptual design stage, preliminary design stage, detailed design
stage, and construction design stage. The conceptual design stage is a pro-
cess meant to develop a few feasible bridge schemes and decide one or
several concepts for further consideration. In the preliminary design stage,