FRP CONFINED CONCRETE STRESS-STRAIN MODEL UTILIZING A VARIABLE STRAIN DUCTILITY RATIO

摘要

A model for representing the compressive behavior of concrete members confined using FRPrncomposite jackets is presented. The distinguishing feature of the analytical model is that the plasticrnbehavior of the FRP-confined concrete can be represented by an experimentally derived variablernstrain ductility ratio, which defines the increase in plastic axial compressive strain versus thernincrease in plastic axial compressive strength of the FRP-confined concrete. This is demonstrated tornbe a function of the stiffness of the confining FRP jacket and the extent of internal damage, ratherrnthan a constant as is typically assumed for steel confined concrete. The model predicts that thernplastic dilation rate of FRP-confined concrete is a function of the confining stiffness of the FRPrnjacket and the type of FRP jacket construction, be it bonded or non-bonded. An expression wasrnobtained for predicting the ultimate compressive strength and strain of FRP- confined concrete basedrnon equilibrium and plasticity analysis. The ultimate compressive strength and strain of the FRPconfinedrnconcrete were found to be a function of the jacket stiffness, the type of jacket construction,rnand the ultimate strain in the FRP jacket. Comparisons with experimental results indicate goodrnagreement.