Prediction Accuracy of Seismic Behavior of RC Noncircular Columns Retrofitted with FRP Sheets and the Impact of Local Concrete Compression Behavior

More than 40 models have been established to date to determine the axial compressive behavior of noncircular (square or rectangular) concrete sections confined with fiber-reinforced polymers (FRPs) under concentric loadings. In this study, these models were classified into four groups, represented by nine analytical models. The accuracies of these models to capture the cyclic response of seven noncircular RC columns subjected to axial and reversible horizontal loads were evaluated. Specifically, the predicted responses revealed that the studied models predicted a premature FRP rupture failure mode, and in turn the simulation process was aborted early, revealing a low deformability capacity. By scrutinizing the available results, it was concluded that the axial compression behavior of the FRP-wrapped concrete was dependent on the applied loads, e.g., concentric axial load or axial load and bending moment. Subsequently, one of the examined models was adopted and revised to consider this effect. The modified model can accurately and safely simulate the lateral response of RC noncircular columns retrofitted with FRP, and it can be expanded for general application after verification against a notably large number of noncircular columns.