An arch bridge is a sort of architectural construction that is supported by a curved, semi-circular shape. Most arches distribute weight evenly and are a popular choice for bridges because they can span long distances without the requirement for poles or other weight-bearing systems to be lowered into the ground. The name "arch" comes from the fact that their shape resembles that of an arch.
Arcs were first used in ancient Egypt to build viaducts before being adopted for use as permanent structures. They are now commonly used in modern engineering projects such as bridges and buildings because of their ability to bear heavy loads over long distances with very little support material needed. There are several different types of arches, but the two most common types used in construction today are the half-round and the continuous loop. Half-round arches have a flat top and bottom while continuous loop arches have a straight side wall with only one corner cut out of it. This allows water to pass through while keeping the building safe from flooding. Arc bridges can also be called "suspension" bridges because they use cables or wires to hold up the deck instead of pillars. These bridges are particularly useful where building codes require an opening in the floor for access or escape purposes (such as in hospitals) because they allow easy passage between the floors without the need for elevators.
An arc bridge can be any size from small bridges used as footbridges to large ones used as road bridges.
Building an arch bridge can be difficult since the construction is fully unstable until the two spans meet in the center. One method is to construct intricate structure, known as "centering," beneath the spans to support them until they meet. The highway above is supported by two beautiful arches. Each arch has four legs called piers that stand out from the ground. The tops of the piers are flat, and the sides are curved. The distance between the tops of the piers is equal to the depth of the curve in the side of the arch. There is a gap between each pair of piers where the arch bridge meets the centering.
The ends of each pier reach down into a hole filled with concrete. The holes should be large enough for a line tied to one end of the pier to pass through without getting stuck. Then crews will pull on this line to lift the other end of the pier so it's even with its partner pier. This process is repeated for each leg of the arch bridge until all the piers have been lifted into place.
After the piers are in place, the next step is to build the arch itself. First, a horizontal member called an arch beam is placed on top of the piers. It should be long enough to span the distance between the tops of the piers. Next, a vertical member called an arch column is placed at each end of the arch beam.
The majority of contemporary arch bridges are composed of reinforced concrete. This bridge is appropriate for situations in which a temporary center may be created to hold the forms, reinforcing steel, and uncured concrete. The finished bridge would then be cast inside the original forms.
Other materials have been used for arch bridges including wood, steel, and masonry. Wood is the earliest material used for this purpose. It can also be the most expensive depending on the quality of the wood and the length of the span. Wood arch bridges are very heavy and require much reinforcement to support their weight. They are also prone to damage from wind and water. Steel has many advantages over wood for this application. It is stronger, more durable, less dense, and less expensive than wood. Also, it does not decay like wood does. Steel arch bridges are usually prefabricated by being rolled into shape at a factory and then transported to the site where they are assembled into place. Masonry arch bridges are similar to reinforced concrete bridges in that they use pre-mixed concrete but instead of using steel bars to give the bridge strength, small stones or brick are used instead. The majority of masonry arch bridges are now made with cement as opposed to mortar. Cement makes the bridge strong and durable while also allowing it to be colored or decorated like stone.