Pullout capacity of non-prestressed bent strands for prestressed concrete girders

In a recently concluded investigation on shear limits in precast, prestressed concrete girders for the Nebraska Department of Roads (NDOR), it was determined that the AASHTO LRFD limit of 0.25f(c)(')bd(v) for maximum shear reinforcement is attainable as long as an adequate number of strands is anchored into the abutment diaphragms. In addition, extending strands in prestressed concrete girders beyond member ends and bending them into cast-in-place pier diaphragms can be a cost-effective method of controlling creep and shrinkage effects in bridges designed as simple spans for girder and deck weights and continuous spans for additional loads. In this paper, the pullout capacity of 0.5 and 0.6 in. (12.7 and 15.2 mm) diameter strands is evaluated. Two numerical design examples are included together with design recommendations for determining the required number and length of strands that need to be bent and embedded into bridge diaphragms.