Experimental and numerical investigation of punching behavior of two-way RC slab with different opening locations and sizes strengthened with CFRP strip

Flat slabs are widely used due to their advantages. However, punching collapse is a situation that should not be ignored during the design as a risk in this type of slab. The openings left around the column or opened later for various reasons negatively affect the punching strength of the slabs. Within the scope of the study, a total of nineteen flat slabs were produced to investigate this negative effect and to eliminate it with an appropriate strengthening method. In the study, the size and position of the two square-section openings adjacent to the column (around the column) were chosen as variables. In addition, identically produced slab test specimens with openings were strengthened with fan-type anchors and CFRP strips. Applied strengthening technique aimed to catch the punching strength of the reference test specimen without opening and, if possible, exceed this value by preventing the punching behavior that occurs in the slabs with openings, as mentioned in the first part of the study. It was determined that the anchored CFRP strips increased the load-carrying capacity of the opening test specimens by 50% on average. Energy dissipation capacity, initial stiffness, maximum bearing capacity, strain behavior of CFRP strips, failure modes, and crack distributions were interpreted using obtained experimental data. The specimens were modeled with the ABAQUS and numerically analyzed, and in the last step, the nu-merical results were interpreted by comparing them with experimental results.