Axial Compressive Behavior of CFRP-Confined Expansive Concrete Columns

Fiber-reinforced polymer (FRP) confined concrete columns use both compressive strength of concrete and tensile strength of FRP efficiently. In this paper, the combination of FRP and expansive concrete was adopted. Ten FRP reinforced concrete disk-shape specimens were made to study the influencing factors of prestress. Eighteen FRP reinforced concrete columns were constructed to investigate the axial compressive behavior. Test variables include the volume ratio of the carbon fiber-reinforced polymer (CFRP) and expansion rate (expansive/non-expansive) of concrete. Based on the results of this investigation, prestress of FRP is found to be inversely proportional to the volume ratio of reinforcement of FRP. The experimental results obtained from the compression tests in terms of stress-strain curves show that the expansive concrete specimens achieved significantly higher inflection stress and ultimate load capacities than conventional non-expansive concrete specimens. Finally, with the effect of prestress taken into account, an improved model aimed at the calculation of the stress at inflection point and ultimate load capacities was proposed. It shows good agreements with experimental results.