There is no doubt that the great number of studies conducted
in the past two decades has led to a good understanding of the
behavior of FRP-confined normal-strength concrete in circular
sections. However, there are still a number of areas where further
research is required. One such area involves the study of
the influence of the type of FRP on the ultimate conditions of
FRP-confined concrete and on the strain reduction factor (ke) of
the FRP jacket.
The model assessment that has been presented herein clearly
indicates the important influence of the size and reliability of the
test databases used in the model development on the overall
performance of the models, especially for the design-oriented
models. Therefore, it is recommended that a carefully chosen
selection criteria is applied in the future database development
efforts. Although the analysis-oriented models with explicitly derived
dilation relationships (e.g. [62,107]) perform reasonably
well, in the future, accuracies of these models can be further improved
through better modeling of the lateral-to-axial strain
behavior of FRP-confined concrete. Furthermore, in future analysis-
oriented model development efforts, due attention should be
given to the implications of the path dependency assumption
discussed in detail in Section 3.2.