In this study, concrete strains were monitored in three pretensioned concrete beams during the cutting of the strands. The beams were 32 ft (9.75 m) long with a 51/2 x 23 in. (140 x 584 mm) rectangular cross section. Four 1/2 in. (13 mm) diameter strands were used in each beam and the concrete had a specified strength of 6000 psi (41.4 MPa). The strains were measured through the use of electrical resistance strain gauges embedded in the concrete and surface mounted to the beams. Strains were also measured through the utilization of surface targets. The transfer length was determined from the strain data and from the end slip of the strands measured with linear variable differential transformers (LVDTs). The results of the transfer lengths were scattered and consistent with measurements made by others. The results of the study showed longitudinal tensile strain near the end of the beams prior to cutting all the strands. These strains were large enough to cause cracking which was not visible after release of all the strands.
