2.1 Effect of curvature on the bond between concrete and CFRP sheets

FRP sheets or laminates are widely utilized for flexural and/or shear strengthening of beams, for confining concrete columns and improving joints performance, mostly in seismic areas. The success of retrofitting techniques depends on more extent on the bond performance between FRP reinforcement and concrete. In fact, under both service and ultimate conditions the interface behaviour plays a fundamental role; cracking and deformations are influenced from bond laws as well as, at the ultimate state, the bond failure can cause an unexpected collapse of the concrete elements.

In particular, when curved concrete members are strengthened with FRP sheets, a combination of shear and normal stresses is transferred at the interface. Such combination involves, in many cases, a premature failure of bond.

In this paper an experimental investigation, aimed to analyse the bond between FRP sheets and curved concrete elements, is reported. At this aim a bending test (modified RILEM test) has been performed on curved 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 stiffness of the reinforcement.

Obtained results are discussed and compared with those regarding concrete members without curvature.

• INTRODUCTION

• EXPERIMENTAL INVESTIGATION

• CONCLUSIONS

• REFERENCES