Shear Strengthening of Modified Reactive Concrete Beams using External Prestressing Technique

This paper presents an analysis of the influence of external prestress strands at shear spans on the shear behavior of rectangular section beams with reduced shear reinforcement. Reduction of shear reinforcement in prestressed beams can make the reinforcement simpler and may increase the ultimate capacity. Four concrete beams were manufactured ;three with prestressing forces and one without prestressing. It was noted that prestressing increases ultimate shear strength about 20%, 66.6% and 86.6% for one strand, two strands and three strands respectively in comparison with non-prestressed beam, extends the non-cracked area, and makes the compression struts less inclined. Ductility and cracking strength are also increased. Prestressing strands reduce the stresses in the stirrups and increase shear strength.