Burr Truss

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The Burr Arch Truss or simply Burr Truss or Burr Arch is a combination of an arch and a multiple kingpost truss design, invented in 1804 by Theodore Burr<ref name="nyc">The Burr Truss. Truss Styles of Covered Bridges. New York State Covered Bridge Society (2006-01). Retrieved on 2006-09-15.</ref>, patented on April 3, 1817<ref name="uspto">Publication Number: X0002769. Publication Images. United States Patent and Trademark Office. Retrieved on 2006-09-15.</ref>, and used in bridges, usually covered bridges.<ref name="odot">Truss Types. Covered Bridge Truss Types. Ohio Department of Transportation Office of Structural Engineering. Retrieved on 2006-09-15.</ref><ref name="tbcbspa">Truss Types. The Theodore Burr Covered Bridge Society of PA, Inc. Retrieved on 2006-07-28.</ref> The design principle behind the Burr arch truss was that the arch should be capable of holding the entire load on the bridge while the truss was used to keep the bridge rigid. Even though the kingpost truss alone was capable of bearing a load, this was done because it is impossible to evenly balance a dynamic load crossing the bridge between the two parts.<ref name="calvert">Calvert, J. B. (2000-10-23). The Burr Truss. Retrieved on 2006-07-28.</ref> The opposite view is also held, based on computer models, that the truss performs the majority of the load bearing and the arch provides the stability <ref name="nyc"/>. Regardless, the combination of the arch with the truss provides a more stable bridge capable of carrying greater weight than with the either the truss or arch alone.