DEVELOPMENT LENGTH OF PRESTRESSING STRAND IN BRIDGE MEMBERS

FHWA is undertaking a research study on the development length of prestressing strand. The objective is to investigate the validity of AASHTO Equation 9-32 for predicting both the transfer length and flexural bond length components of development length for fully bonded, straight, uncoated, and epoxy-coated prestressing strand. Toward this end, the effects of strand diameter [9.5, 12.7, and 15.2 mm (3/8, 0.5, and 0.6 in.)], concrete strength, strand coating (uncoated or epoxy coated), and strand spacing on development length will be evaluated. This phase of the research study involves full-size prestressed concrete bridge members. A total of 32 AASHTO Type II prestressed concrete bridge girders and 32 prestressed concrete deck panels were fabricated at a precast concrete plant in Winchester, Virginia. All of the members will undergo transfer and development length experimentation. The fabrication, instrumentation, and experimentation procedures, as well as partial results, are described. Experimentation is scheduled to be finished in the spring of 1995.