Measurement of Development Length of 0.5-Inch and 0.6-Inch Diameter PrestressingStrand in Fully Bonded Concrete Beams

摘要

The report focuses on determining the development length of 0.5-inch and 0.6-inchprestressing strands in fully bonded beams. I-shaped beams were used and made to resemble an AASHTO section complete with a composite deck. Nineteen development length tests were performed on the beams, which were loaded statically in flexure until failure. Flexural failures typically developed their ultimate flexural capacity, then experienced large deformations (ductility) before failing by yielding of the strands and crushing of the concrete. Bond failures were characterized by general slip of the strand through the specimen and gross displacements of the strand relative to the concrete (end slip). In most cases, bond failures were accompanied by brittle shear failures. These bond/shear failures resulted in sudden and total collapse of the beam, with little or no warning. From the test results, the embedment length was plotted versus the mode of failure. Development length is defined by the boundary length between flexural failure and bond failure. Overall, the test results were extremely well behaved, with good correlation between the different tests. Clear definitions of the development lengths were obtainable.