Transfer and Development Length of 0.6-Inch Diameter Prestressing Strand at Two Inch Spacing in Fully Bonded Normal Strength Concrete Composite Texas Type C Beams

The purpose of this study was to determine the transfer and development length of 0.6-inch diameter prestressing strand in normal strength concrete beams. Two standard Texas Type C beams with a composite slab were fabricated. The beams had design strengths of 4300 psi at release of the prestressing force and 7000 psi at 28 days. The concrete slab had a design strength of 6000 psi at 28 days.

Transfer length was determined by measuring the concrete strain at the center of gravity of the prestressing strand at the bottom of the beams. The concrete strain occurred due to the release of the prestressing force. Development length was determined by loading each end of the two beams to failure. The embedment length, that is, the distance from the end of the beam to the first of two concentrated loads, was varied for each test. The development length tests for these two beams resulted in flexural failure with the four tests having embedment lengths of 120, 93, 78, and 72 inches. The results are compared with design equations from current ACI 318 and AASHTO codes and previous research reports.