HOW TO STRENGTHEN FLAT SLABS ON PUNCHING SHEAR – TRADITIONALLY WITH STEEL OR INNOVATIVE, BY USING FIBER COMPOSITE MATERIALS?

In the paper the effectiveness of external steel and composite reinforcement was compared and discussed. The differences between the physical features of both materials, which are relevant for their use as additional, external reinforcement of the support zones, were presented. The results of authors’ and others experimental studies on strengthening reinforced concrete slabs by using external longitudinal reinforcement in the form of CFRP strips and steel flat bars, as well as by increasing the stiffness od support zone with steel sheets and CFRP tapes, were discussed. It was stated that moderate effectiveness of composite materials as external punching shear reinforcement resulted from higher deformability of CFRP as well as premature deboning (prior to rupture of fibers).