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Arch Bridges

Basic principles of arch construction have been known and used successfully for centuries.
Magnificent stone arches constructed under the direction of engineers of the ancient Roman Empire are still in service after 2000 years, as supports for aqueducts or highways. One of the finest examples is the Pont du Gard, built as part of the water-supply system for the city of Nıˆmes, France.
Stone was the principal material for arches until about two centuries ago. In 1779, the first metal arch bridge was built. Constructed of cast iron, it carried vehicles over the valley of the Severn River at Coalbrookedale, England. The bridge is still in service but now is restricted to pedestrian traffic. Subsequently, many notable iron or steel arches were built.
Included was Eads’ Bridge, with three tubular steel arch spans, 502, 520, and 502 ft, over the Mississippi River at St. Louis. Though completed in 1874, it now carries large daily volumes of heavy highway traffic.
Until 1900, stone continued as a strong competitor of iron and steel. After 1900, concrete became the principal competitor of steel for shorter-span arch bridges.
Development of structural steels made it feasible to construct long-span arches economically.
The 1675-ft Bayonne Bridge, between Bayonne, N.J., and Staten Island, N.Y., was completed in 1931. The 1000-ft Lewiston-Queenston Bridge over the Niagara River on the United States–Canadian border was put into service in 1962. Availability of more highstrength steels and improved fabrication techniques expanded the feasibility of steel arches for long spans. Examples include the 1255-ft-span Fremont Bridge in Portland, Ore., finished in 1973, and the 1700-ft-span New River Gorge Bridge near Fayetteville, W. Va., opened in 1977.
Nearly all the steel arches that have been built lie in vertical planes. Accordingly, this section discusses design principles for such arches. A few arch bridges, however, have been constructed with ribs inclined toward each other. This construction is effective in providing  lateral stability and offers good appearance. Also, the decrease in average distance between the arch ribs of a bridge often makes possible the use of more economical Vierendeel-girder bracing instead of trussed bracing. Generally, though, inclined arches are not practicable for bridges with very wide roadways unless the span is very long, because of possible interference with traffic clearances. Further, inclined arch ribs result in more complex beveled connections between members.

—–14.1. Types of Arches
—–14.2. Arch Forms
—–14.3. Selection of Arch Type and Form
—–14.4. Comparison of Arch with Other Bridge Types
—–14.5. Erection of Arch Bridges
—–14.6. Design of Arch Ribs and Ties
—–14.7. Design of Other Elements
—–14.8. Examples of Arch Bridges
—–14.9. Guidelines for Preliminary Designs and Estimates
—–14.10. Buckling Considerations for Arches
—–14.11. Example-Design of Tied-Arch Bridge

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