Effect of Draped Reinforcement on Behavior of Prestressed Concrete Beams


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Title: Effect of Draped Reinforcement on Behavior of Prestressed Concrete Beams

Author(s): James G. MacGregor, Mete A. Sozen, and Chester P. Siess

Publication: Journal Proceedings

Volume: 57

Issue: 12

Appears on pages(s): 649-678

Keywords: none

Date: 12/1/1960

Tests on I9 simply supported pretensioned concrete beams with draped prestressed reinforcement are described and compared with the results of tests of similar beams with straight prestressed reinforcement. The Principal variables included: concrete strength, steel percent-age, length of shear span, and the angle and type of drape profile. Web reinforcement was used in only five beams. In general, it was concluded that draping the longitudinal wires did not increase either the inclined cracking load or the shear strength of the prestressed concrete beams tested. Instead, the trend of the test results indicated a reduction in both the inclined cracking load and the ultimate strength of the beams with draped wires. A comparison of the behavior of beams with draped and straight wires showed that the detrimental effect of the drape on shear strength could be ascribed to the earlier formation of flexural cracks in regions of combined bending and shear and the consequent earlier development of in- clined cracks. For extreme combinations of the critical variables, an inclined crack occurred prior to the forma- tion of flexural cracks in its vicinity, in which case draping the wires caused an increase in stren t h which could be estimated on the basis of an uncracke 8 section analysis. The beams with draped reinforcement required more web reinforcement to produce a flexural failure than similar beams with straight reinforcement.