SHEAR DESIGN CONSIDERATION FOR PRETENSIONED PRESTRESSED BEAMS

Typical cross sections commonly used for pretensioned precast concrete beams are the thin-webbed tees or channels. For beams with low shear span-to-depth ratio, where shear could be dominant, the presence of shear cracks may cause premature failure due to slippage of the prestressing strands and alter the mode of failure. This paper discusses the influence of slippage of the prestressing strands on the beam behavior of pretensioned prestressed concrete tee beams, tested statically up to failure. Contribution of various shear reinforcement configuration, crack behavior, overall deformation, and mode of failure are discussed. Based on the test results, a proposed mechanism is introduced to describe the overall behavior of such beams, and design recommendations are presented.