Mohr-coulomb model for rectangular and square FRP-confined concrete

An analytical stress-strain model for fiber reinforced polymer (FRP) confined concrete is developed for predicting the compressive and dilation behavior of rectangular and square cross-sections with rounded corners. An iterative as well as a non-iterative two parameter Mohr-Coulomb yield criterion are introduced for analyzing the compressive behavior of FRP-confined concrete. A new diagonal Poisson's ratio formulation is employed which describes the dilation behavior of FRP-confined concrete as a function of the mechanical properties of unconfined concrete, FRP jacket, section geometry, and internal damage of the confined concrete core. Equilibrium and strain compatibility are used to obtain the ultimate concrete compressive strength and strain as a function of the effective confining stiffness of the FRP jacket and transverse strains. Simplified expressions are derived for the FRP reinforcement ratio which precludes strain-softening in rectangular and square FRP-confined concrete sections.