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Bowstring Arch
A tied-arch bridge is an arch bridge in which the outward horizontal forces of the arch(es) caused by tension at the arch ends to a foundation are countered by equal tension of its own gravity plus any element of the total deck structure such great arch(es) support. The arch(es) have strengthened chord(s) that run to a strong part of the deck structure or to independent tie-rods below the arch ends. Description Thrusts downwards on a tied-arch bridge deck are translated, as tension, by vertical ties between the deck and the arch, tending to flatten it and thereby to push its tips outward into the abutments, like for other arch bridges. However, in a tied-arch or bowstring bridge, these movements are restrained not by the abutments but by the strengthened chord, which ties these tips together, taking the thrusts as tension, rather like the string of a bow that is being flattened. Therefore, the design is also called a bowstring-arch or bowstring-girder bridge. The elimination o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tied-arch Bridge Pattern
A tied-arch bridge is an arch bridge in which the outward horizontal forces of the arch(es) caused by tension at the arch ends to a foundation are countered by equal tension of its own gravity plus any element of the total deck structure such great arch(es) support. The arch(es) have strengthened chord(s) that run to a strong part of the deck structure or to independent tie-rods below the arch ends. Description Thrusts downwards on a tied-arch bridge deck are translated, as tension, by vertical ties between the deck and the arch, tending to flatten it and thereby to push its tips outward into the abutments, like for other arch bridges. However, in a tied-arch or bowstring bridge, these movements are restrained not by the abutments but by the strengthened chord, which ties these tips together, taking the thrusts as tension, rather like the string of a bow that is being flattened. Therefore, the design is also called a bowstring-arch or bowstring-girder bridge. The elimination o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nanjing Dashengguan Yangtze River Bridge
The Nanjing Dashengguan Yangtze River Bridge, formerly Third Nanjing Yangtze Bridge, is the first cable-stayed bridge with steel tower stanchions located in Nanjing, China. It is the third crossing of the Yangtze River at Nanjing. The cable-stayed portion is just a part of the 4.7 kilometers of the complete bridge. Constructed in slightly more than two years at a cost of $490 million, this bridge features dual 215 meters towers. The main span measures 648 meters. When it was completed in 2005 it was the third longest cable stayed span in the world. It still ranks among the top 20. The bridge carries the G42 Shanghai–Chengdu Expressway and the G2503 Nanjing Ring Expressway. The bridge has renamed on 20 December 2019. Structure The deck superstructure is an orthotropic box girder 3.2 m deep and 37.5 wide that accommodates three lanes of traffic in each direction. Also the bridge has a center lane used in case of emergency. The deck is supported by 168 stay cables. Each cab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Federal Highway Administration
The Federal Highway Administration (FHWA) is a division of the United States Department of Transportation that specializes in highway transportation. The agency's major activities are grouped into two programs, the Federal-aid Highway Program and the Federal Lands Highway Program. Its role had previously been performed by the Office of Road Inquiry, Office of Public Roads and the Bureau of Public Roads. History Background The organization has several predecessor organizations and complicated history. The Office of Road Inquiry (ORI) was founded in 1893. In 1905, that organization's name was changed to the Office of Public Roads (OPR) which became a division of the United States Department of Agriculture. The name was changed again to the Bureau of Public Roads in 1915 and to the Public Roads Administration (PRA) in 1939. It was then shifted to the Federal Works Agency which was abolished in 1949 when its name reverted to Bureau of Public Roads under the Department of Commerce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
