An arch bridge is a type of bridge in which the load-bearing structure is a curved arch that transfers forces primarily through compression to the abutments at each end. This structural principle has been used for thousands of years, from ancient Roman aqueducts to modern highway overpasses built in steel and concrete.
Application
Arch bridges are chosen for their structural efficiency, durability, and aesthetic qualities. They are especially well-suited to spanning valleys, rivers, and gorges where solid ground is available to resist the horizontal thrust of the arch. Key aspects include:
- Deck-arch bridges: The roadway sits on top of the arch, supported by vertical columns (spandrels) that rise from the arch to the deck. This is the most traditional configuration.
- Through-arch bridges: The arch rises above the deck, and the roadway is suspended from the arch using hangers or cables. This design is common for longer spans where a deck-arch would require an impractically tall structure.
- Tied-arch bridges: Also called bowstring arches, these use a horizontal tie (the deck itself or a separate tension member) to resist the outward thrust, eliminating the need for massive abutments.
- Materials: Historically built from stone and brick, modern arch bridges use reinforced concrete, prestressed concrete, steel, or combinations thereof.
- Span range: Arch bridges can span from a few meters (small masonry footbridges) to over 500 meters (the Chaotianmen Bridge in China spans 552 meters).
- Construction methods: Modern concrete arch bridges are often built using temporary falsework, cantilever construction from both sides, or precast segments assembled in place.
The arch shape works because it follows the natural line of thrust for the applied loads, keeping the material in compression and minimizing bending moments.
Related terms
- Voussoir
- Abutment
- Keystone
- Spandrel
- Thrust line
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