Suspension bridges - Computational Analysis and Design of Bridge Structures - page 370

Cable saddle
Main cable

Pylon

Hangers

Stiffening girder

Side span Main span Side span

Figure 12.1 A typical suspension bridge.

Side span Main span Side span

Figure 12.2 A single-span suspension bridge.

into the stiffened girders at the end of side spans. This is the so-called self-
anchored suspension bridge. As the stiffened girders will resist axial com-
pression from main cables, the span capacity of self-anchored suspension
bridges is limited.
Pylons in most long-span suspension bridges are usually designed not to
resist longitudinal bending moment due to the structural weight of stiff-
ened girders. This type of pylons is flexible in the longitudinal direction.
For short- or multispan suspension bridges, pylons may be designed as rigid
to resist longitudinal bending due to dead or live loads. The high-strength
parallel wires are widely used for the main cables in modern suspension
bridges.
The suspension bridge has a long history (Kawada 2010). Its original
forms that two suspending ropes carrying walking boards directly were con-
structed in ancient China. The development of modern suspension bridges
started in the early nineteenth century. Jacob's Creek Bridge, which had a
center span of 21.3 m, was built in the United States in 1801. Its main cables
were made of iron chains. Niagara Falls Bridge, in which parallel wire cables
were used for the main cables, was built in 1855. It had a main span of 251 m
and was the world's first working railway suspension bridge. Due to the great
increase of railway loads, it was later replaced by Whirlpool Rapids Bridge
in 1897. The Golden Gate Bridge, with a main span of 1280 m, was built in
the San Francisco Bay area in 1937. It had the longest main span till 1964.
The Severn Bridge, with a main span of 988 m, was built in England in 1966.
Box girder and diagonal hangers were used in the Severn Bridge. In 1981, the
Humber Bridge, with a main span of 1410 m, was built in England. It had
the longest main span till 1997. The Akashi Kaikyo Bridge, with the world's
longest main span of 1991 m, was built in 1998. Table 12.1 lists the top 10
world's longest suspension bridges so far.