SUSPENSION BRIDGES

Suspension Bridge

•Deck is hung below suspension cables on vertical

suspenders

•Usually has two towers that hold up the horizontal

cables.

•From these main horizontal cables hang vertical

cables that are attached to the deck of the bridge

•Used for the longest spans.

•Cables- suspend the roadway (tension)•Towers- stabilize wire cables (compression)•Anchorages- key to the structure, mass that keeps cables tight, gives the bridge structure

Suspension Bridge- Parts

With anchorages

Without anchorages

Suspension Bridge

Suspension Bridge- Structural Analysis

 The main forces are tension in the cables and compression in the pillars. Since almost all the force on the pillars is vertically downwards and they are also stabilized by the main cables, the pillars can be made quite slender.

Suspension Bridge- Structural Analysis

Cables suspended via towers hold up the road deck. The weight is transferred by the cables to the towers, which in turn transfers the weight to the ground. This is a type of bridge that is able to stretch to extreme lengths and be capable of lasting a very long time.

It is suspended in the air, is able to withstand natural disasters such as earthquakes or tornadoes better than another type of bridge.

Suspension Bridge- History

• Early suspension bridges - simple and crude with a narrow walkway that was suspended from chains or rope.• Used in the 7th century by the Mayans, and later in China and Tibet. • However these theories weren’t proved, the first suspension bridge design was drawn by Faust Vrancic in his book “Machinae Nove” in 1595.

Suspension Bridge- Types

Simple Suspension Bridge

It is the oldest type of suspension bridge, usually constructed as a foot bridge. In this type a flexible deck is provided which is supported by the cables anchored to the earth.

Golden Gate Bridge, San Francisco

Suspension Bridge - Types

Kingston Rhinecliff Bridge, New York

Under spanned suspension bridge

the main cables hang entirely below the bridge deck, but are still anchored into the ground in a similar way to the conventional type

Suspension Bridge

Stressed Ribbon Bridges

A modern descendant of the simple suspension bridge. The deck lies on the main cables, but is stiff, not flexible.

Maldonado Bridge, Uruguay

 -They can span longer distances than any other type of bridge. - They require less material to build, resulting in reduced construction cost. - Don’t have to shut down a waterway in order to build the bridge. -They can withstand earthquakes better than stiff conventional bridges.   

Suspension Bridges - Advantages

-Road deck can vibrate and even twist is high

winds. 

-The road deck lacks the stiffness required to carry

heavy railroad traffic. 

- Some areas of the bridge are difficult to install

and maintain. 

Suspension Bridges - Disadvantages

The Akashi-Kaikyo bridge in Japan

The longest bridge in the world - 6529 feet long.

Suspension Bridges

The Great Belt Bridge, Denmark

Suspension Bridges

Humber Bridge, United Kingdom

Mackinac Bridge, USA

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