Unified model for concrete columns confined by fiber-reinforced polymer jackets with practical applications

Despite numerous experimental and analytical investigations on the compressive behavior of fiber-reinforced polymer (FRP) confined concrete sections, researchers have been unable to develop a unified theoretical stress-strain model that can accurately capture and describe the axial compressive and resultant transverse dilation behavior of various FRP-jacketed concrete column shapes. In this dissertation, a mechanics-based unified stress-strain model is introduced; this model is applicable to FRP-confined concrete sections of various shapes that can accurately capture both the compressive and dilation behavior of rectangular, square, oval, circular, and elliptical FRP-confined concrete members using the concept of diagonal dilation and diagonal equilibrium of the FRP-confined concrete section with a minimum number of curve-fitting parameters based on experiments. This is accomplished by including the general concepts of elasticity, damage mechanics, soils mechanics, and plasticity theory in the development of a theoretically sound mechanics-based stress-strain model for FRP-confined concrete that takes into consideration the macrostructural effects of the increase in internal damage (i.e., increase in dilation) and the beneficial effects contributed by the kinematic restraint provided by the confining elastic FRP jacket. The proposed stress-strain model's ability to accurately describe the compressive behavior of FRP-confined concrete of various geometrical shapes will depend on its ability to capture the restraint sensitivity of the confined concrete core and the effects that the shape of the confining FRP jacket has on the jacket's ability to restrain the transverse dilation of the confined concrete core.