South Russia's biggest cable-strayed bridge built in Sochi

SOCHI (Itar-Tass) - A cable-strayed bridge, the biggest one
in entire Russia's south, is being built in Sochi within the project of
the Adler-Krasnaya Polyana highway and railway, an official from Russian
Railways Co (RZD) said on Saturday.
The bridge will be 800 meters in length, its towers will be 86 meters
high, and each of the spans will measure 327 meters, Yevgeny Solntsev, the
head of RZD's Sochi department of railway reconstruction and construction
of railway facilities, told journalists.
According to Solntsev, there will be 79 bridges along the road, with
the longest one measuring about three kilometers. "The unique
cable-strayed bridge will be the highway's landmark, it will be
recognizable across the globe," he noted.
The cable-strayed motorway bridge will be located after the third
tunnel complex. It will be commissioned in mid-2012. The Adler-Krasnaya
Polyana road will comprise six railway tunnels, three motorway tunnels,
and three maintenance galleries. The total length of tunnels is 29
kilometers, and the total length of bridges - 37 kilometers. The entire
road is expected to be put into operation in the first six months of 2013.
A typical cable-stayed bridge is a continuous girder with one or two
towers erected above piers in the middle of the span. From these piers,
cables are attached diagonally to the girder to provide additional
support. Cable-stayed bridges have a low center of gravity which makes
them strong against earthquakes, but at the same time makes them
vulnerable to uneven sinking of the ground. Cable-stayed bridges carry the
vertical main-span loads by nearly straight diagonal cables in tension.
The towers transfer the cable forces to the foundations through vertical
compression. The tensile forces in the cables also put the deck into
horizontal compression.