Stress–Strain Behavior of FRP-Confined Concrete under Eccentric Loading

Because of its complex cracking mechanisms and nonlinear behavior, concrete exhibits a distinctive stress–strain behavior under multiaxial stress conditions or varying load paths. However, for some scenarios, concrete’s stress–strain behavior cannot be directly measured, for instance, nonuniformly confined concrete members subjected to eccentric loading. This study adopts an analytical method based on sectional analysis principles, to obtain the actual stress–strain curves of fiber-reinforced polymer (FRP)-confined concrete subjected to eccentric loading. Full-field strain measurements are performed on both the compression and the tension sides of the concrete during a series of eccentric loading tests. These strains are also verified by strain measurements on the side region according to the plane section assumption. In addition, second-order eccentricity caused by lateral deflection effects is considered to calculate the instantaneous moment under incremental eccentric loading. The accurate strain measurement and moment calculation ensures the reliability of obtaining stress–strain curves based on the proposed analytical method. Based on these stress–strain curves, this study further investigates the effects of key parameters, including loading eccentricity, section shapes, and FRP thickness, on the eccentric load stress–strain curves. This study also contributes to the existing database to establish a cross-sectional analysis of FRP-confined concrete subjected to eccentric loading.