Arch bridges have been used for thousands of years to span rivers, valleys and other obstacles. The arch is one of the oldest and most fundamental architectural elements, and it is known for its strength and stability. Arch bridges transfer the bridge’s weight and the traffic it carries to abutments, which are solid supports on either end of the bridge.
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Arch bridges have been used for centuries and are known for their remarkable natural strength. Today, arch bridges continue to be an important engineering solution for modern infrastructure projects. This article will explore arch bridges’ history, advantages, and disadvantages.
Arch bridge: History
An arch bridge utilises a curved, flexuous support structure to span a gap and bear the weight of loads on top of the opening. The arch has structural components that resist compression, tension, and axial forces.
The arch shape allows the weight to be evenly distributed, making building longer and more durable bridges possible than other types of bridges. Arch bridges have been used throughout history in many different cultures and have become iconic landmarks worldwide.
Originally constructed from stone or brick, modern arch bridges are typically made from reinforced concrete or steel, which allows them to have longer spans with lower profiles than their traditional counterparts.
Arch bridge: Types
Arch bridges come in a variety of types that can be classified differently. Below are some examples of the various types of arch bridges.
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Deck arch bridge
This arch bridge has a deck or roadway on top of the arch. The arch is typically made of stone, brick, or concrete and is shaped like a semi-circle or segment of a circle. It consists of a horizontal deck supported by one or more arches. The arches transfer the weight of the bridge and its load to the abutments or piers on either end.
Through arch bridge
Unlike the deck arch bridge, the through arch bridge has its roadway passing through the arch, and the arch is usually located above the roadway. This design gives the bridge an elegant and iconic appearance, and it’s commonly used for pedestrian bridges.
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Moment-tied arch
A moment-tied arch is a type of bridge where the arches are held in place by cables attached to the ends of the arch. It allows the arch to withstand lateral forces and bending moments. This type of bridge is commonly used for long spans.
Fixed‐fixed concrete arch
A fixed-fixed concrete arch is a bridge where the ends of the arch are fixed in place, meaning they cannot move. The arch is in a curved shape and is reinforced with steel bars. This type of bridge is suitable for short to medium spans.
Pinned‐pinned concrete arch
It is similar to the fixed-fixed arch bridge, but the supports are pinned instead of fixed, allowing the arch to rotate slightly. This type of bridge is suitable for medium to long spans.
Bowstring arch
The bowstring arch bridge has a deck that sits on top of an arched truss made of steel. The truss is curved like a bow, and the deck is attached to the top of the truss, giving it a distinctive appearance.
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Aqueducts and canal viaducts
These arch bridges are typically long and narrow and carry water or other fluids over long distances. They can be made of stone, brick, or concrete and may have multiple arches or spans. They are commonly used to transport water over long distances and are often built with multiple arches to span wide valleys.
Corbel arch bridge
This arch bridge is constructed by gradually cantilevering courses of stone or brick from either side of a gap until they meet at the top, creating an arch. It’s a very old technique for building bridges and is still used in some parts of the world. Corbel arch bridges are suitable for short spans and low traffic volumes.
Arch bridge: Advantages
Arch bridges offer several advantages, including:
- Increased resistance: The arch shape of the bridge provides a high level of strength, making it more resistant to bending forces that could cause it to deform.
- Efficient design: The arch design ensures that a load of anything crossing the bridge is evenly distributed, minimising stress on any particular part of the structure.
- Structural soundness: Modern arch bridges are designed to be lightweight, making them structurally sound and able to withstand significant loads.
- Minimal distortion: The arch shape of the bridge ensures that it can withstand extreme pressure or weight without distorting or becoming damaged.
- Increased strength over time: Arch bridges gain strength through a natural process that strengthens them as they support more weight.
- Cost-effective: Arch bridges are a cost-effective means of short-distance transportation, making them an asset to local economies.
- Aesthetically pleasing: The elegant arch design of these bridges makes them an attractive addition to any landscape.
Arch bridge: Disadvantages
Despite their many advantages, arch bridges have some disadvantages, including:
- Restricted span: Arch bridges can only span a certain distance, requiring multiple arches or additional reinforcement materials to support larger loads.
- Location constraints: Building an arch bridge requires a suitable location with solid and stable foundations on either side.
- Increased maintenance: Natural materials used to construct arch bridges are susceptible to environmental factors such as wind and weather, requiring additional maintenance over time.
- Need for additional support: Arch bridges require more support from their sides than standard bridges, necessitating the presence of a structurally sound abutment or bank.
- Lengthy construction time: Arch bridges require a specific construction process, making them time-consuming.
FAQs
What is an arch bridge?
An arch bridge is supported by an arch or a curved structure spanning an open space, like a river or a valley. The arch transfers the weight of the bridge and the traffic it carries to the abutments, which are the supports at each end of the bridge.
What are some advantages of arch bridges?
Arch bridges have several advantages over other types of bridges. They are strong and span longer distances than other bridges, such as beam bridges. They are also aesthetically pleasing and can be built to blend in with the surrounding environment.
What are some famous examples of arch bridges?
Some famous examples of arch bridges include the Sydney Harbour Bridge in Australia, the Golden Gate Bridge in San Francisco, the Pont du Gard in France, and the Aqueduct of Segovia in Spain.
How are arch bridges constructed?
Arch bridges are typically constructed using a wooden or steel frame built in the desired arch shape. The frame is then covered with concrete or other materials to form the final bridge. The arch shape allows the bridge to distribute weight evenly across the span and withstand compression and tension forces.
What is the maximum span of an arch bridge?
The maximum span of an arch bridge depends on several factors, such as the materials used to build the bridge, the height and shape of the arch, and the weight of the traffic it will carry. Some arch bridges can span distances of over 1,000 foot, while others are much shorter.
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