In engineering , span is the distance between two adjacent structural supports (e.g., two piers ) of a structural member (e.g., a beam ). Span is measured in the horizontal direction either between the faces of the supports ( clear span ) or between the centers of the bearing surfaces ( effective span ):
15-626: The Ethel Kennedy Bridge is a beam bridge built in 2004 that carries Benning Road over the Anacostia River in Washington, D.C. It is an eight-lane bridge with pedestrian lanes on both sides. A separate Washington Metro bridge carrying the Blue , Orange and Silver lines crosses over the bridge near its western terminus, and parallels the bridge on the north. A third bridge in the area carries Benning Road over Kingman Lake. In 1797,
30-435: A deck across the top of them, to a main beam either side supporting a deck between them. The main beams could be I-beams , trusses , or box girders . They could be half-through , or braced across the top to create a through bridge . Because no moments are transferred, thrust (as from an arch bridge ) cannot be accommodated, leading to innovative designs, such as lenticular trusses and bow string arches , which contain
45-555: Is known as simply supported . The simplest beam bridge could be a log (see log bridge ), a wood plank , or a stone slab (see clapper bridge ) laid across a stream. Bridges designed for modern infrastructure will usually be constructed of steel or reinforced concrete , or a combination of both. The concrete elements may be reinforced or prestressed . Such modern bridges include girder , plate girder , and box girder bridges, all types of beam bridges. Types of construction could include having many beams side by side with
60-609: The horizontal forces within the superstructure . Beam bridges are not limited to a single span . Some viaducts such as the Feiyunjiang Bridge in China have multiple simply supported spans supported by piers. This is opposed to viaducts using continuous spans over the piers. Beam bridges are often only used for relatively short distances because, unlike truss bridges, they have no built in supports. The only supports are provided by piers. The farther apart its supports,
75-506: The Benning Road Reconstruction Project replaced the 586-foot bridge built in 1934 with a 548-foot, 8-lane, 5-span, continuous, multi-girder bridge with steel elements masked by concrete panels to closely resemble the 1934 span. The new bridge, like the one it replaced, carries water, gas, electricity and phone lines. It also included wide sidewalks, a new pedestrian gateway to Kingman Island and connections to
90-799: The District. By 1814, the bridge—now also known as "Upper Bridge"—was in disrepair. During the War of 1812 , the U.S. military commander of the Military District of Washington burned Stoddert's Bridge in an attempt to stop the British from invading the city of Washington. On March 3, 1815, the United States Congress passed legislation reimbursing the Anacostia Bridge Co. for the destruction of its bridge. The bridge
105-685: The RiverParks on both sides of the river. In 2008, the District Council voted to rename the Benning Road Bridge after Ethel Kennedy , the widow of the late Robert F. Kennedy , for whom a nearby stadium was named. In a May 20, 2014, ceremony, the bridge was officially renamed the Ethel Kennedy Bridge to honor her for her devotion to many social and environmental causes during her later years, especially in
120-462: The federal government and the toll removed. In disrepair due to the large amount of traffic over the span, it was almost completely rebuilt in 1868. Ewell's Bridge was replaced with a steel bridge in 1892. Work on a replacement to that bridge began in January 1933 and cost $ 450,000 at the time. The 8-span bridge made of steel beams encased in concrete on simple spans opened on December 18, 1934. It
135-535: The neighborhoods along and near the Anacostia River. The Bridge was inspected by the District of Columbia Department of Transportation (DDOT) in 2014, and found to be structurally sound. Beam bridge Beam bridges are the simplest structural forms for bridge spans supported by an abutment or pier at each end. No moments are transferred throughout the support, hence their structural type
150-403: The second one for power lines , overhead telecommunication lines, some type of antennas or for aerial tramways . Span is a significant factor in finding the strength and size of a beam as it determines the maximum bending moment and deflection . The maximum bending moment M m a x {\displaystyle M_{max}} and deflection δ m
165-554: The state of Maryland (which then controlled the area which would later become the District of Columbia) issued a charter to Benjamin Stoddert , Thomas Law, and John Templeman to build a bridge across the Anacostia River. Stoddert owned land (known as "Long Meadows") on the eastern shore of the Anacostia River, and a bridge would have helped him develop him land. The right to build a bridge was not exercised until 1805, when Chain Bridge
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#1732801160986180-400: The weaker a beam bridge gets. As a result, beam bridges rarely span more than 250 feet (80 m). This does not mean that beam bridges are not used to cross great distances; it only means that a series of beam bridges must be joined together, creating what is known as a continuous span. Bridge span A span can be closed by a solid beam or by a rope. The first kind is used for bridges,
195-482: Was 586 feet long, 106 feet wide with 8' sidewalks on each side. In 1975, the west bound deck was replaced. In the late 1990s an analysis of the existing bridge showed that the bridge was unsuitable for rehabilitation and that it needed to be replaced. The replacement was broken into two bridges, with one over Kingman Lake and the other over the Anacostia. The bridge over Kingman Lake was built in 2000. In 2002-2003,
210-452: Was rebuilt in 1815 by Dr. Thomas Ewell, who renamed it Ewell's Bridge (although it was also known as the "Anacostia Bridge"). In 1825, Ewell sold the bridge to Benning, who renamed it Benning's Bridge. Benning built a new bridge at the site in the 1830s (although not all sources agree on the exact date). After a major flood in 1840, the bridge was repaired. It was purchased in August 1848 by
225-460: Was swept away during floods. Stoddert then formed the Anacostia Bridge Co., and that same year erected a $ 20,000 wooden bridge known as Stoddert's Bridge in this location. In the 1790s, "Captain" William Benning came from Virginia and purchased 330 acres (1.3 km) of land on the western end of Stoddert's Bridge. The site was one of the first crossings over the Anacostia River. The bridge and "Benning's Road" were important eastern routes in and out of
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