Development Length of Strands in Prestressed Panel Subdecks (145-2)

This report describes the results of field and laboratory studies of prestressed concrete panels of the type proposed for use as a new method of highway bridge construction. Twenty panels, utilizing two different strand sizes, concrete types and panel lengths were considered. Study objectives included the determination of the development length of the prestressing strands shortly after fabrication and the effect of cyclic loading on this development length. Changes in panel stiffness as a result of fatigue loading were also monitored.|Test results showed that an average of 22 in. of development length was required for 3/8 in. diameter, 7-wire strands pretensioned with a force of 13.75 kips. An average development length of 34 in. was required for 1/2 in. diameter strands pretensioned with a force of 27.50 kips.|Cyclic loading was found to have negligible effect on strand development length or on panel stiffness.