An analytical study of spiral type shear reinforcement considering bond stress

Abstract

Flat plate slab is cost-efficient structural system widely used in high rise building, apartment and parking garages. But flat plate-column connections are so weak against punching shear failure that it may cause collapse of overall structure. In this study, spiral shear reinforcement which increases the shear strength and ductility of the plate-column connection and has good workability was proposed. And experimental test was performed to verify the shear capacity of spiral shear reinforcement. As a result, the test results showed that the strength and deformation capacity of the specimens with the spiral shear reinforcement were improved by 1.47 and 1.5 times those of the unreinforced specimen. The current code does not accurately estimate the punching shear strength of slab-column connection with shear reinforcement because shear strength of concrete does not consider the effects of slab thickness. And slab is so slender that punching failure may occur before shear reinforcement reached yield stress. Therefore, modified equation of ACI code for punching shear strength was proposed by finite element analysis, using LUSAS 14.3.