Bond between Masonry and CFRP Sheets in Presence of Curvature

Repair and strengthening of masonry and reinforced concrete structures is becoming a very important topic in the field of the Civil Engineering. At this aim, the use of Fibre Reinforced Plastic (FRP) for repair and/or retrofitting of concrete and masonry structures is becoming a successful and increasingly utilised technique. The success of retrofitting techniques depends on more extent on the bond performance between the FRP reinforcement and the substrate. In particular, when curved concrete members are strengthened with FRP sheets, a combination of shear and normal stresses is transferred at the interface, causing, in many cases, a premature failure. In the present paper the influence of curvature of FRP-strengthened masonry elements is investigated, both in terms of bond-slip laws and failure mechanisms. In detail, an experimental investigation, aimed to analyse the bond between FRP sheets and curved masonry elements, is reported. At this aim a bending test has been performed on curved masonry elements reinforced with CFS (Carbon Fiber Sheet). In particular the state of stress and strain at the interface is analyzed varying the curvature of the elements and the width of the bonded sheets. Finally a theoretical analysis is performed in order to interpret the obtained results