Twenty-two precast, pretensioned concrete beam specimens were fabricated and tested to determine the influence of concrete strength on the transfer length and development length of pretensioning strand. The main variables were the concrete compressive strength, with f~, at 28 days, varying from 4500 to 12,900 psi (31 to 89 MPa), and the strand diameter, which included%, !1 and 0.62 in. (9.5, 12.7 and 15. 7 mm) diameters. Expressions are given for the influence of concrete strength on the transfer length and development length of pretensioning strand.
