Cantilever bridge

Cantilever bridge

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A traditional Tibetan log cantilever bridge

A cantilever bridge is a type of bridge that is constructed using cantilevers, which are structures that project horizontally into space, supported on only one end. This design allows for bridges to span large distances without the need for support piers in the middle of the span, making them ideal for crossing wide rivers or valleys.

Design and Construction

Cantilever bridges are typically constructed using a combination of steel and concrete, although traditional materials such as wood can also be used, as seen in the

A traditional Tibetan log cantilever bridge

. The basic principle involves two arms extending from opposite sides of the obstacle to be crossed, meeting in the middle. These arms are anchored at the ends and are balanced by counterweights. The

A human model demonstrating the cantilever principle

illustrates how the cantilever principle works, with the arms extending outwards and being supported at only one end.

Examples of Cantilever Bridges

One of the most famous examples of a cantilever bridge is the Forth Bridge in Scotland, which was completed in 1890 and spans the Firth of Forth. Another notable example is the Quebec Bridge in Canada, which is the longest cantilever bridge span in the world.

The

Diagram of a cantilever bridge

shows the structural design of a typical cantilever bridge, highlighting the cantilever arms and the central span.

Advantages and Disadvantages

Cantilever bridges offer several advantages:

• They can span long distances without the need for central supports.
• They are stable and can support heavy loads.
• They allow for construction over difficult terrain or water without the need for temporary supports.

However, they also have some disadvantages:

• They require careful engineering and design to ensure stability.
• They can be more expensive to build than other types of bridges due to the complexity of the design.

Dismantling and Maintenance

Cantilever bridges, like all bridges, require regular maintenance to ensure their safety and longevity. The

Dismantling of the old East Span of the San Francisco-Oakland Bay Bridge

shows the process of dismantling a cantilever bridge, which involves carefully removing the cantilever arms and central span.

Also see

• Beam bridge
• Arch bridge
• Suspension bridge
• Truss bridge