The arch bridge works by distributing compression through its semicircular form into a horizontal thrust restrained by its abutments, or legs. Longer bridges often consist of a series of arches, as the greater the curvature, the more tension on the bridge's underside. If the arch is too big, tension overcomes the natural strength of the semicircular design.Know More
Though there are architectural variations to arch bridges, the basic structure remains the same. In the past, arch bridges were often made of stones, with a keystone in the middle that bore the bulk of the weight. The more weight the bridge bore, the stronger its structure became. Due to their inherent weight, these bridges required extremely sturdy foundations. Most modern arch bridges are made of reinforced concrete.
Arch bridges are durable. The oldest standing arch bridge in the world, the Arkadiko Bridge on the Peloponnese in Greece, was built around 1300 B.C. but is still used today. Many Roman bridges and aqueducts, built in segmented arches, still stand. Medieval builders improved the span and height of arch bridges by modifying the thickness of the arch barrels. Modern arch bridges include the Lupu Bridge in Shanghai, which is more than 1,800 feet long, and the New River Gorge Bridge in West Virginia, which is 1,700 feet long.Learn more about Architecture
Videos on bridge building can be found on a number of websites. Ron Hazelton Home Improvement Online (RonHazenton.com) has a video on how to build a wooden foot bridge. The website lays out detailed instructions in several steps, each accompanied by a separate video. The resulting laminated bridge spans 12 feet, rests on heavy block piers and has side rails and decking.Full Answer >
Suspension bridges are box roadways supported by stanchions and steel cables of enormous tensile strength which themselves are strung on suspenders which themselves are anchored at the bridge's ends. This design ensures that when the roadway experiences load, it is transferred to the cables as tension.Full Answer >
The statement "London bridge is falling down" refers to the deterioration of the London Bridge. The statement does not refer to a particular bridge, as London Bridge was the name given to several 19th century bridges that spanned the River Thames. Although different materials were used to build or repair the bridges, they continued to deteriorate. "London Bridge is Falling Down" is also a nursery rhyme and game.Full Answer >
The purpose of the Golden Gate Bridge is to connect San Francisco to Marin County, Calif. Before the bridge opened in 1937, the only practical route between what is now Marin County and San Francisco was by ferry across San Francisco Bay. At the time, San Francisco was the largest U.S. city reached primarily by ferry.Full Answer >