This paper presents the results of a research work aimed to determine the efficiency of using different materials to increase the
punching shear strength of slab–column connections. These materials are steel bars, and glass or carbon fiber reinforced
polymers as shear reinforcement stirrups.
Over the last few years, the use of Fiber Reinforced Polymer (FRP) for strengthening concrete structures have been
investigated by many researchers. Most of these researchers studied the repair and strengthening of reinforced concrete beams
and columns. The use of FRP in strengthening concrete slabs in flexure is done by bonding FRP to the tension face of these
slabs. The use of FRP in repair and strengthening punching shear in flat plates is a new application.
This research shows the results obtained from an experimental investigation on a total of 26 half -scale two-way slabcolumn
interior connections tested under punching shear, the research included two specimens without shear reinforcement as
control, three specimens reinforced with inner steel stirrups for comparison, and eighteen specimens strengthened with Glass
Fiber Reinforced Polymer (GFRP), Carbon Fiber Reinforced Polymer (CFRP), and steel reinforcement as external stirrups. The
remaining three specimens repaired with the same materials.
Test parameters investigated were the shape of FRP and steel stirrups, the number of stirrups rows and the spacing between
these rows for the different material types. The test results showed a noticeable increase in punching shear resistance, and slab
stiffness for repaired or strengthened specimens, which also failed in a ductile manner. Finally, equations for prediction the
punching shear strength for slab-column connections strengthened or repaired using different materials (Steel bars-GFRP-CFRP)
were predicted and examined against test results. |
