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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.
Patent image for Marsh's Reinforced Arch Bridge Brush Creek Bridge. James Barney Marsh (April 12, 1856 – June 26, 1936) was an American engineer and bridge designer. He patented a new design for arch bridges. Marsh gave Archie Alexander, the first African-American to graduate as an engineer from Iowa State University, his first job.
The design principle behind the Burr arch truss is that the arch should be capable of bearing the entire load on the bridge while the truss keeps the bridge rigid. Even though the kingpost truss alone is capable of bearing a load, this was done because it is impossible to evenly balance a dynamic load crossing the bridge between the two parts. [5]
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]
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 ...
The network arch type, with multiple crossings, i.e. overlap in the horizontal axis, was developed by Per Tveit to avoid this. [3] Lohse bridges have a tie conversely curved to the arch. The bridge deck is supported by a third structural element hanging underneath.