be in one of several forms, but in the vast majority
of cases, this curve is or can be approximated as a
monotonically ascending bi-linear curve. Such FRPconfined
concrete is said to be sufficiently confined.
Any FRP-confined concrete with an actual confinement
ratio less than 0.07 is said to be insufficiently
confined. Such concrete is not expected to possess a
compressive strength significantly above that of
unconfined concrete and the FRP may rupture at a
low hoop strain. Such insufficiently-confined concrete
should not be allowed in design.