Science Fair Project Encyclopedia
Compression arch bridge
A compression arch bridge is the earliest type of bridge that could form long spans using stone, brick, or unreenforced concrete. Such materials are strong in compression and somewhat so in shear, and cannot resist much force in tension.
In most arch bridges the roadway rides on or above the supporting structure. Early roman aqueducts use a vertical stack of such bridges, progressing from long wide spans to shorter and narrower as elevation is added in order to obtain height while maintaining rigidity in the supporting structure by avoiding tall, thin vertical elements.
This type is still used in canal viaducts and roadways as it has a pleasing shape, particularly when spanning water, as the reflections of the arches form a visual impression of circles or ellipses.
Most modern compression arch bridges are made from reinforced concrete. This type of bridge is suitable where a temporary supporting falseworks may be erected to support the forms, reinforcements, and uncured concrete. When the concrete as sufficiently set the forms and falseworks are then removed.
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