- Stressed ribbon bridge
:"This article is concerned with a particular type of suspension bridge, the stressed ribbon type.:For an index to the several types see
suspension bridge types .A stressed ribbon
bridge is a tension structure (similar in many ways to asimple suspension bridge ) in which the roadway follows a catenary arc between supports. Unlike the simple span the ribbon is stressed in compression, which adds to the stiffness of the structure (simple suspension spans tend to sway and bounce). The supports in turn support upward thrusting arcs that allow the grade to be changed between spans (where multiple spans are used). Such bridges are typically made from concrete reinforced by steel tensioning cables. Where such bridges carry vehicle traffic a certain degree of stiffness is required to prevent excessive flexure of the structure, obtained by stressing the concrete in compression.The
Maldonado bridge , located inMaldonado, Uruguay , illustrated externally below, was created by the engineerLeonel Viera (1913-1975) to expand the area ofPunta del Este . This pioneered the construction sequence now typical for concrete segment bridges of this type. After placement of the principal cables, precast concrete tiles were placed to form the initial structure. The cables were then prestressed by loading sandbags upon the tiles, followed by final concretization of the gaps between tiles. Removal of the sandbags then compressively stressed the concrete structure, enhancing its stiffness and durability under load. An identical bridge was later constructed parallel to the first.An example
The concrete segment stressed ribbon
footbridge shown below carries pedestrians, bicyclists, and pipelines across the Rogue River atGrants Pass, Oregon External links
* [http://en.structurae.de/files/photos/115/maldonado01.jpgStructurae: Image of one of the two Maldonado stressed ribbon bridges]
* [http://www.fulbright.org.uy/Western%20Hemisphere%20Conference/sightseeingspots.htm Tourist article containing a reference to the above bridge (the Maldonado bridge)]
* [http://arquitecto.com.uy/trobo/viera.php Spanish language site concerning the works of Don Leonel Viera]
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