Ultimate Horizontal Shear Strength Of Prestressed Split Beams

The report deals with the horizontal shear resistance and behavior of prestressed concrete composite beams when the interface is selected to pass through the centroid of the composite section. Composite beams proportioned in this manner are referred to as prestressed split beams. A total of eight simply supported split beams were statically tested with the major variables being interface roughness and reinforcement parameter r fy. (r and fy are the percent and yield point of the web reinforcement across the interface.) All test beams were posttensioned and grouted and had the same nominal dimensions. Beams with rough interfaces showed an increase in the ultimate horizontal shear strength of about 100 psi over that of 'duplicate' beams with smooth interfaces. The ductility and the energy absorption capacity increased with r fy. The ultimate horizontal shear strength for beams with r fy = 0 was in excess of 400 psi and increased at the rate of about 60 psi per 100 psi increase in r fy. The two beams with the highest value of r fy failed in flexure. In spite of developing slip at the interface, these two beams developed the calculated flexural resistance based on full composite action. The horizontal shear resistance of the test beams failing in horizontal shear was much higher than the computed values based on the ACl code. (Author).