Numerical investigation into RC slabs strengthened using FRP and hybrid anchors

Abstract

It is well understood that reinforced concrete (RC) members strengthened using fiber reinforced polymers (FRP) are limited by premature debonding which results in significant underutilisation of the FRP tensile strength. In order to mitigate this mode of failure, different types of anchorage systems have been developed and of these, hybrid anchors have shown significant success in shifting the mode of failure from premature debonding to FRP rupture. However, experimental data on hybrid anchors in flexural strengthening applications has been limited to date and insufficient data is currently available for development of anchor specification guidelines. This paper aims to generate additional data by developing and validating 3D finite element (FE) models to investigate the effect of hybrid anchors on RC slabs strengthened with FRP sheets. After successful validation of the model, parametric studies were conducted by varying concrete strength between 25 and 65 MPa in order to generate the required data. Lastly, two models are proposed which can be used to calculate the maximum FRP design strain when using hybrid anchors in FRP strengthened RC slabs subjected to flexural actions.