Stress path-based compressive strength model of FRP-confined recycled aggregate concrete

The compressive strength model of fibre-reinforced polymer (FRP) confined recycled aggregate concrete (RAC) is important in practical engineering designs. The existing research has showed that the compressive strength of FRP-confined RAC can be predicted by the models for FRP confined natural aggregate concrete (NAC). However the accuracy of existing compressive strength models for FRP-confined NAC vary greatly because of the unclear understanding of the confinement mechanisms. Previous research has shown that the axial stress of confined concrete tends to be path-dependent. In this study, a confining stress path-based compressive strength model of FRP-confined RAC is proposed based on theoretical analyses of the confining stress path of FRP-confined RAC. In the proposed model, an effect index is determined to express the influence of confining stress path on the compressive strength. The relationship between the effect index and confinement ratio and that between lateral stress dominant index and confinement ratio are obtained. The proposed model is verified by comparison with previous experimental test results and those predicted by existing representative models. It is found that the compressive strength of FRP-confined RAC is path-dependent for small confinement ratios (less than 0.43) and path-independent for large confinement ratios (larger than 0.43).