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An arch bridge is a bridge with abutments at each end shaped as a curved arch.Arch bridges work by transferring the weight of the bridge and its loads partially into a horizontal thrust restrained by the abutments at either side, and partially into a vertical load on the arch supports.
Colorado Street Bridge, an example of a false skew arch. The strength of a regular arch (also known as a "square" or "right" arch) comes from the fact that the mass of the structure and its superincumbent load cause lines of force that are carried by the stones into the ground and the abutments without producing any tendency for the stones to slide with respect to one another.
The actual resolution of forces will depend upon the bridge' design. [1] If no horizontal thrusting forces are generated, this becomes an arch-shaped truss which is essentially a bent beam – see moon bridge for an example. If horizontal thrust is generated but the apex of the arch is a pin joint, this is termed as a three-hinged arch.
A fixed arch bridge, that is one without hinges, exerts a bending moment at the abutments and stresses caused by change of temperature or shrinkage of concrete have to be taken up by the arch. A two-hinged arch has a hinge at the base of each arch (the springing point), while a three-hinged arch has a third hinge at the crown of the arch. [3]
Rossgraben bridge (Rüeggisberg) near Bern, Switzerland, showing the hinge at mid-span of this three-hinged arch. The practical arch bridges are built either as a fixed arch, a two-hinged arch, or a three-hinged arch. [103] The fixed arch is most often used in reinforced concrete bridges and tunnels, which have short spans.
The through arch bridge usually consists of two ribs, [5] although there are examples like the Hulme Arch Bridge of through arches with a single rib. When the two arches are built in parallel planes, the structure is a parallel rib arch bridge. When the two arch ribs lean together and shorten the distance between the arches near the top, the ...