Experimental and numerical study into the punching shear strengthening of RC flat slabs using post-installed steel bolts

Abstract

This paper presents a strengthening technique of reinforced concrete (RC) flat slabs using post-installed steel bolts. Two large-scale RC slabs representing an interior slab-column connection were tested. One slab was without shear reinforcement and was used as a control slab and the second slab was strengthened against punching shear using steel bolts with end anchorage steel plates. The punching tests were compared with the numerical results using finite element method (FEM). Numerical results showed good correlations with the experimental results in terms of the load-displacement response, concrete strain and failure mode. The results showed that the strengthening technique increased the load up to flexural failure of the slabs and improved ductility of slab relative to the control. The strengthening technique was also successful and contributed to changing the failure mode from brittle punching shear mode to ductile flexural failure mode. Photogrammetry was used in this research. Photogrammetry technique holds several advantages over traditional contact instrumentations including that it is inexpensive, simple for analyzing the results and a remote visualization technique. The displacement profile along the span of the slab and rotation has been compared with the results obtained from the traditional sensors.