A CRITICAL EVALUATION OF THE AASHTO PROVISIONS FOR STRAND DEVELOPMENT LENGTH OF PRESTRESSED CONCRETE MEMBERS

This paper presents a critical evaluation of recent proposals for calculating the development length of prestressing strands. The results of an extensive testing program on a variety of prestressed concrete members are discussed. An evaluation of the results indicates that there is a direct interaction between shear and bond at the ends of prestressed concrete members. The effect of this interaction on the development length is important yet ignored in all existing proposals. This paper examines the relevance of recently proposed modifications of methods for calculating transfer and development lengths presented in the AASHTO Specifications. It presents proposed modifications based on a number of investigations conducted over the past ten years. The present study offers a new rational approach for estimating the development length and compares it against other proposals.