Full-range load-deflection response of FRP-strengthened RC flexural members anchored with FRP anchors

Abstract

The flexural resistance of reinforced concrete (RC) members such as beams and slabs can be enhanced by bonding fibre-reinforced polymer (FRP) composite plates to their tension face. The effectiveness of the strengthening can be compromised though by premature debonding failure of the FRP which can occur at strains significantly lower than the strain capacity of the FRP. Anchorage of the FRP strengthening can, however, increase its usable strain. A convenient means with which to represent the structural behaviour of such a strengthened and anchored member then is via its load-deflection response. The task of how to model this response therefore arises. The authors, as well as other research groups, have derived closed-form solutions which describe the complete load-deflection response of FRP-strengthened RC flexural members of which pre-defined moment-curvature relationships are observed. This paper reports an extension to such existing theory in order to incorporate the anchorage effect. The theory is finally calibrated with test results of FRP-strengthened RC slabs which have been anchored with FRP anchors. The paper sets a framework for future work centred on quantification of the FRP anchor effect.