Truss bridge - Wikipedia
Selected Bridges on Southern-Central Region Tours Tour A-1 Tour B Tour C T. Allan Comp, “Bridge Truss Types: A Guide to Dating and Identifying,”. Other name/site number;. Clear Creek Camelback Truss Bridge (preferred); LT; A-1O .. Bridge Truss Types: A guide to dating and identifYing. Nashville. Nashville, Tenn. American Association fro State and Local History, Stapled Pamphlet. 12 pages; with illustrations of bridges. With three holes punched for.
Infurther modifications were made, which included removal of portal and panel point knee braces and the addition of plates to the end posts. Croix River Bridge was built in in response to a perceived need to fill a gap in the east-west transportation network in this area. The bridge was built by the St.
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Croix Interstate Bridge Company. It was designed by C. Turner, a prominent engineer from Minneapolis. The bridge is one of six Pennsylvania truss bridges known to have existed in Wisconsin, and probably one of a similar number in Minnesota. By the s there was sufficient local, commercial and tourist traffic to justify a crossing here.
The nearest alternate bridges were fifty miles apart at St. Croix Falls and near Danbury, respectively. Three ferries provided additional river crossings but were unreliable. After a search of some time to find the means to fund such a bridge, a private company was formed.
Croix Interstate Bridge Company was chartered for the purpose of building, owning and operating this one bridge. Although complaints were made about the high tolls, the company is said to have paid a dividend only once in the 20 years it operated the bridge. After a long and extensive public debate about public ownership of the bridge, the states of Minnesota nad Wisconsin took over ownership on February 10, Turner was born in and began his career with the N.
He subsequently worked for a number of bridge companies before establishing a private consulting practice in Minneapolis in He is probably best known for his invention of the flat slab "mushroom system" of concrete floor construction and spiral mushroom concrete floor system.
In other applications the trusses may be stacked vertically. The Warren truss was patented in by James Warren and Willoughby Theobald Monzani, and consists of longitudinal members joined only by angled cross-members, forming alternately inverted equilateral triangle -shaped spaces along its length, ensuring that no individual strutbeam, or tie is subject to bending or torsional straining forces, but only to tension or compression.Truss Bridge
In the image at right, note the use of doubled prefabrications to adapt to the span and load requirements. In other applications the trusses may be stacked article source. The Baltimore truss is a subclass of the Pratt truss. A Baltimore truss has additional bracing in the lower section of the truss to prevent buckling in the compression members and to control deflection.
It is mainly used for rail bridges, showing off a simple and very strong design. Pratt truss uses the intersection of the verticals and the lower horizontal tension members to anchor the supports for the short-span girders under the tracks among other things.
With the Baltimore truss, there are almost twice as many points for this to happen because the short verticals will also be used to anchor the supports. The Bollman Truss Railroad Bridge at Savage, Marylandis the only surviving example of a revolutionary design in the history of American bridge engineering. The type was named for its inventor, Wendel Bollmana self-educated Baltimore engineer.
It was the first successful all-metal bridge design patented in to be adopted and consistently used on a railroad. The design employs wrought iron tension members and cast iron compression members. The use of multiple independent tension elements reduces the likelihood of catastrophic failure.
The structure was also easy to assemble. The Wells Creek Bollman Bridge is the only other bridge designed by Wendel Bollman still in existence, but it is a Warren truss configuration. The bowstring arch through truss bridge was patented in  by Click at this page Whipple. These diagonals result in a structure that more closely matches a Parker truss or Pratt truss than a true arch. This type of truss is particularly suited for timber structures that use iron rods as tension members.
Most trusses have the lower chord under tension and the upper chord under compression. In a cantilever truss the situation is reversed, at least over a portion of the span. The typical cantilever truss bridge is a "balanced cantilever", which enables the construction to proceed outward from a central vertical spar in each direction. Usually these are built in pairs until the outer sections may be anchored to footings. A Bridge Truss Types A Guide To Dating And Identifying gap, if present, can then be filled by lifting a conventional truss into place or by building it in place using a "traveling support".
In another method of construction, one outboard half of each balanced truss is built upon temporary falsework. When the outboard halves are completed and anchor the inboard halves may then be constructed and the center section completed as described above.
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The Fink truss was designed by Albert Fink of Germany in the s. This type of bridge was popular with the Baltimore and Ohio Railroad. Link Appomattox High Bridge on the Norfolk and Western Railway included 21 Fink deck truss spans from until their replacement in The relatively rare Howe truss, patented in by Massachusetts millwright William Howeincludes vertical members and diagonals that slope up towards the center, the opposite of the Pratt truss. A truss in the form of a K due to the orientation of the vertical member and two oblique members in each panel.
One of the simplest truss styles to implement, the king post consists of two angled supports leaning into a common vertical support. This type of bridge uses a substantial number of lightweight elements, easing the task of construction.
Truss elements are usually of wood, iron, or steel. In a simple form of truss, Town's lattice trusswas patented, and had the advantage of requiring neither high labor skills nor much metal. Few iron truss bridges were built in the United States before Truss bridges became a common type of bridge built from the s through the s.
Examples of these bridges still remain across the US, but their numbers are dropping rapidly, as they are demolished and replaced with new structures. As metal slowly started to replace timber, wrought iron bridges in the US started being built on a large scale in the s. Bowstring truss bridges were a common truss design during this time, with their arched top chords. The bowstring truss design photo fell out of favor due to a lack of durability, and gave way to the Pratt truss design, which was stronger.
Again, the bridge companies marketed their designs, with the Wrought Iron Bridge Company in the lead. As the s and s progressed, steel began to replace wrought iron as the preferred material. Other truss designs were used during this time, including the camel-back. By the s, many states developed standard plan truss bridges, including steel Warren pony truss bridges. As the s and s progressed, some states, such as Pennsylvaniacontinued to build steel truss bridges, including massive steel through-truss bridges for long spans.
Other states, such as Michiganused standard plan concrete girder and beam bridges, and only a limited number of truss bridges were built. Roadbed types[ edit ] The truss may carry its roadbed on top, in the middle, or at the bottom of the truss.