Rio-Niteroi Bridge

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Rio-Niterói Bridge ,the sixth longest  bridge in the world and the longest prestressed concrete bridge in the southern hemisphere also known as President Costa e Silva Bridge . It runs 13.290 kilometres (8.258 mi) long – 8.836 kilometres (5.490 mi) over water and the bridge's 300-metre (980 ft) central span is 72 metres (236 ft) high in order to allow the passage of hundreds of ships entering and leaving the bay every month. OVER-WATER APPROACHES The over-water approach spans consist of twin precast post tensioned concrete box girders constant span length of 80 m is used for the continuous spans. Expansion joints are provided 20 m from the piers in every fifth or sixth span. The structure depth is 4.7 m. The piers for the approach structure are of cellular reinforced concrete and rest on footing blocks near the water surface and on 2-m-diameter reinforced concrete piles reaching to competent founding strata below water. Precast concrete segments were cast in a yard, barged...
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Reaction and Type - Supports

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ROLLER SUPPORTS

Roller supports are free to rotate and translate along the surface upon which the roller rests. The surface can be horizontal, vertical, or sloped at any angle. The resulting reaction force is always a single force that is perpendicular to, and away from, the surface.
Roller supports are commonly located at one end of long bridges. This allows the bridge structure to expand and contract with temperature changes. The expansion forces could fracture the supports at the banks if the bridge structure was "locked" in place.
Roller supports can also take the form of rubber bearings, rockers, or a set of gears which are designed to allow a limited amount of lateral movement.
How it looks..
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Roller support in a Bridge


PINNED SUPPORTS
A pinned support can resist both vertical and horizontal forces but not a moment. They will allow the structural member to rotate, but not to translate in any direction.
Many connections are assumed to be pinned connections even though they might resist a small amount of moment in reality. It is also true that a pinned connection could allow rotation in only one direction; providing resistance to rotation in any other direction. .
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Pinned support

A single pinned connection is usually not sufficient to make a structure stable. Another support must be provided at some point to prevent rotation of the structure. The representation of a pinned support includes both horizontal and vertical forces.

FIXED SUPPORTS
Fixed supports can resist vertical and horizontal forces as well as a moment.
Since they restrain both rotation and translation, they are also known as rigid
supports. This means that a structure only needs one fixed support in order to
be stable. All three equations of equilibrium can be satisfied. A flagpole set into a
concrete base is a good example of this kind of support. The representation of
fixed supports always includes two forces (horizontal and vertical) and a moment.

REACTIONS :


                               

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