Punching Behavior of RC Slabs Retrofitted with FRP Sheets under Eccentric Loading

Abstract

Punching shear is one of the main design criteria in flat slabs construction due to its brittle nature. In addition to the vertical load, unbalanced moment is generated and resulted in considerable increase in the punching shear stress in the slab. The presence of such moments results in unsymmetrical punching shear stresses around the column. Flat slabs of the existing structures may require strengthening due to a variety of reasons: to accommodate the increase in acting loads as a result of changing building usage; improve the performance of already existing concrete that did not satisfy the required design value; and/or to fortify void-cut areas within the column vicinity.

This thesis aims to investigate the Punching behavior of RC slabs retrofitted with different strengthening schemes using carbon fiber reinforced polymers (CFRP) under eccentric loading. The experimental program consists of six RC two-way specimens with overall dimensions equal to 1800 x 1800 x 150-mm with clear spans equal to 1500 x 1500-mm. Different fiber amount, spacing and distribution were used in the specimens to evaluate the best strengthening scheme. The fibers were stitched in the specimens to form the punching shear reinforcement. The obtained results show that CFRP were able to enhance the ultimate load capacity of specimens by values up to 59% and increase the ductility by values up