Abstract：To study the stress-strain relationship of CFRP confined concrete with initial stress
under the sustained load, a total of twelve columns with different initial stress level were
tested under three types of the sustained load modes. The influence of initial stress and
sustained load on the long-term deformation, the peaks of the strain and the stress of concrete,
and the stress-strain relationship of CFPP confined concrete columns were observed. The
experimental results show that the axial strain of CFRP confined concrete is smaller than that of
unconfined ones, and the axial strain rises with the increase of initial stress level. The peaks
of stress and strain of concrete are affected by the sustained load and the initial stress.
Meanwhile, the peaks of the stress and strain of concrete decrease with the initial stress level.
The characteristic of stress-strain curve under the long-term loading is similar with that under
short-term loading. A method to calculate the long-term deformation of the CFPR confined concrete
column is proposed. In this method, ACI 209-92 model and Findley model are adopted to simulate the
creep of concrete and CFRP, respectively. Moreover, a model for stress-strain curve of CFRP
confined concrete column is presented, considering initial stress level and long-term sustained
load mode. The results show that the numerical curve agrees well with the experimental curve.
