Punching Shear Strength of Post-Tensioned Transfer Slab-Column Connections

Abstract

Current design codes specify the need for two-way shear strength analysis for prestressed slab-to-column connections. This paper is an investigative study of said interaction for post-tensioned (PT) transfer slabs. Two-way shear strength and failure mode of the tested PT slab specimens were evaluated. To analyze the interaction quantitatively, concentric compression tests were performed on recent PT transfer slabs having small shear span-to-depth ratios. Test parameters included the number and layout of post-tensioning reinforcement. The test results demonstrated that the two-way shear strength of the PT transfer slab specimens was 53%-87% greater than that of conventional RC transfer slab specimen. Increase was tied to concentrated layout of post-tensioning tendons rather than distributed layout. The two-way shear strengths of the test specimens were compared with predictions under current design methods for PT flat plates and the strut-tie model.