Numerical Punching Shear Analysis of Unbonded Post-Tensioned Slabs with Inverted-U Shaped01 Jul 2018 00:00
At cracked stage, the post-tensioned concrete beams resist shear through a different set of mechanisms, the accepted mechanisms are: interface shear transfer, dowel action of longitudinal reinforcements, shear transfer in compression zone, transversal reinforcements, and vertical component of the force in the draped of prestressing strands. To increase the shear capacity in such beams, special shear reinforcements can be used. This paper presents the results of an experimental investigation on shear strength for bonded post-tensioned concrete beams (PTB) reinforced with inverted-U shaped reinforcement; those results were compared with beams provided with stirrups reinforcements. Based on ACI code, the nominal shear stress in transversal reinforcement is limited to 8 (f 'c 0.5) psi (0.67(f 'c 0.5) MPa), but however, it does not differentiate between the types of shear reinforcements. The results indicate that the nominal shear stress in inverted-U shaped and stirrups reinforcements are 14.4 (f 'c 0.5) psi (1.2 (f 'c 0.5) MPa) and 12.72 (f 'c 0.5) psi (1.06 (f 'c 0.5) MPa), which gives an approximately 13 % increase in shearing strength. Good correlations exist between the predicted and the actual experimental results.