Grade 300 Prestressing Strand and the Effect of Vertical Casting Position

摘要

The purpose of this investigation was (1) to compare the differences in the transfer length, development length, and flexural strength among Grade 300 strand, the traditional Grade 270 strand, and the predictions of these properties obtained using current code equations for prestressed concrete members, and (2) to determine the effect the as-cast vertical location of the strands (top-strand effect) on these properties. The current code provisions by the American Association of State Highway and Transportation Officials and the American Concrete Institute are based on years of experimental research on the traditional Grade 270 strand. The scope of this project was limited to the fabrication and testing of 20 pretensioned, prestressed beams, 10 of which contained Grade 270 and 10 of which contained Grade 300 strands constructed and tested in the Structures and Materials Laboratory at Virginia Tech.