Continious Prestressed Concrete Beams


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Title: Continious Prestressed Concrete Beams

Author(s): Fritz Leonhardt

Publication: Journal Proceedings

Volume: 49

Issue: 3

Appears on pages(s): 617-634

Keywords: no keywords

Date: 3/1/1953

One of the major problems in the design and construction of continuous prestressed concrete beams is the friction between the prestressing steel and the cable casing. Measures for reducing this friction are discussed and include the use of sliding provisions in the cable channels, concentrating the prestress-ing steel in a few cables, and arranging the cables in horizontal layers instead of a circular or ringlike arrangement. Instead of curving the prestressing elements continuously, a polygonal shape can be used, made up of long straight lines and short curved sections. Reducing friction without disturbing bond of the tables to the concrete can be accomplished by keeping the proper relationship between straight and curved portions. By the use of these measures, friction coefficients as low as 0.07 have been attained on a three-span girder.