Creep of FRP-wrapped concrete columns with or without fly ash under axial load

This paper presents an experimental work on the long-term deformation properties of four FRP-wrapped concrete columns (FWCCs) with low-volume fly ash (FA) as admixture, and a theoretical study on the creep of FWCCs with or without FA in the concrete mix. Theoretically, considering the creep of concrete under triaxial stresses and the interaction between concrete core and fiber reinforced polymer (FRP) wraps, an analytical model, based on the Model B3 or modified Model B3 for the creep of concrete without or with FA, and the power law for the creep of FRP, is developed to study the creep of FWCC. Validations against creep data from literatures and the experimental results in this paper show the model works well. Additionally, the influences of various parameters on the creep of FWCC are investigated. The creep of FWCC with FA is shown to be less than that of FWCC without FA. And the composition and compressive strength of concrete are demonstrated to affect the creep of FWCC obviously.