Use of Modern Materials
Most modern arch bridges are made from reinforced concrete. This type of bridge is suitable where a temporary centring may be erected to support the forms, reinforcing steel, and uncured concrete. When the concrete is sufficiently set the forms and falseworks are then removed. It is also possible to construct a reinforced concrete arch from precast concrete, where the arch is built in two halves which are then leaned against each other.
Many modern bridges, made of steel or reinforced concrete, often bear some of their load by tension within their structure. This reduces or eliminates the horizontal thrust against the abutments and allows their construction on weaker ground. Structurally and analytically they are not true arches but rather a beam with the shape of an arch. See truss arch bridge for more on this type.
A modern evolution of the arch bridge is the long-span through arch bridge. This has been made possible by the use of light materials that are strong in tension such as steel and prestressed concrete.
Read more about this topic: Arch Bridge
Famous quotes containing the words modern and/or materials:
“The experience of the gangster as an experience of art is universal to Americans. There is almost nothing we understand better or react to more readily or with quicker intelligence.... In ways that we do not easily or willingly define, the gangster speaks for us, expressing that part of the American psyche which rejects the qualities and the demands of modern life, which rejects “Americanism” itself.”
—Robert Warshow (1917–1955)
“He was no specialist except in the relation of things.... He took most of his materials at second hand.... But no matter who mined the gold, the image and superscription are his.”
—Woodrow Wilson (1856–1924)