Evaluation of code requirement for 0.6 in. (15 mm) prestressing strand

This study investigated the effects of concrete strength and strand surface condition on the transfer and development lengths of fully bonded and various combinations of bonded and debonded strands in AASHTO Type I I-beams. Furthermore, the effect of H-bars on the transfer length and end-slip of the strand was investigated. Six beams with lower-strength concrete and rusty strand were tested. The results were used to evaluate the requirements of ACI and AASHTO and equations by Buckner and Lane. Transfer length results showed that ACI, AASHTO, and Buckner equations are conservative but the Lane equation is very conservative. Development length results showed that ACI and AASHTO requirements are conservative for fully bonded strand and are overly conservative for debonded strand. Buckner and Lane equations are very conservative for fully bonded strand and decreasingly conservative for debonded strand H-bars were effective in decreasing strand end slip and shear crack widths within the H-bar region.