Prestressing and preloading effect in RC slabs strengthened with normal and pretensioned CFRP EBR strips

This paper presents a parametric study on reinforced slabs strengthened by prestressed externally bonded CFRP strips with various geometric features and physical parameters. In analysed tests two different anchorages types were used: mechanical with rigid fixed the cut-ends of the strip to the concrete surface and adhesive with gradual reduction of prestressing force. Based on the conducted analysis it was concluded that the initial, prestressing force in the strip introduced before it is glued to the surface of the RC slabs has fundamental influence on the level of the element carrying capacity causing delamination of the composite from the surface of the concrete. Neither the initial nor the maximum strain of the composite is relevant if ultimate load are analysed. Also the dimensions of the strip and the strength of the concrete in the strengthened element are not as important as the prestressing force in this case.