Experimental Verification of Punching Shear with FRP Reinforcement: Innovations in the New Eurocode Generation

The new generation of Eurocodes for concrete structures, specifically the draft standard FprEN 1992-1-1:2023, introduces an innovative application of non-prestressed Fibre Reinforced Polymer (FRP) reinforcement (Annex R). This standard represents the first standardized method for the application of FRP reinforcement, an area that has been lacking in European standards to date. Composite reinforcement using glass (GFRP) or carbon fibre (CFRP) provides a perspective alternative in specific applications where it can replace traditional steel or stainless steel reinforcement. The main advantages are high corrosion resistance and electromagnetic neutrality. This allows for application in structures exposed to a high level of environmental impact. However, composite reinforcement with glass fibres exhibits sensitivity to alkaline environments and has a lower modulus of elasticity compared to steel reinforcement. Due to the linear elastic stress-strain diagram for FRP reinforcement, the design of structures with FRP reinforcement requires a different approach than traditional concrete reinforcement. The standard FprEN 1992-1-1:2023 provides specific approaches for the design of concrete elements using FRP reinforcement, considering various types of loading. In the context of design resistance to punching shear, the standard offers a specific relationship that determining the punching shear resistance for using longitudinal FRP reinforcement. In situations where it is necessary to consider punching shear reinforcement, the shear reinforcement should not be made from FRP. The transition to the new Eurocode brings significant changes in the method of design punching shear resistance compared to the current standard ČSN EN 1992-1-1. The aim is to verify the accuracy of the newly introduced relationships for punching shear through a real experiment with steel and FRP longitudinal reinforcement. The experiment will also research the effect of the adding FRP stirrups on the overall resistance under local loading conditions.