Performance analysis of load–strain models for circular columns confined with FRP composites

The use of FRP composites for the confinement of concrete has become an important aspect to consider on strengthening of concrete columns. It is important therefore that accurate modelling tools are available for the design of this system considering, not only the peak values of load and strain, but also the complete stress–strain behaviour. A wide group of authors have proposed several models specific for FRP-confined concrete based either on theoretical assumptions (analysis-oriented-models – AOMs) or on mathematical calibration from testing results (design-oriented-models – DOMs). This article carries out the implementation and analysis of nine existing models for circular concrete columns in view of axially tested reinforced concrete columns confined with CFRP with three different diameters: 150; 250 and 400mm. The global shape of curves, peak compressive load, stress–strain relation, axial-to-lateral relation and dilation response were studied to conclude which models’ curves were closer to tests. Quantification of errors in face of the testing results was carried out for the most important parameters – ultimate load, strain and lateral stress – as well as for other curve parameters. Some models are accurate in predicting the peak load, though only few can accurately predict the load–strain and dilation behaviour.