Nonlinear modeling of ultimate strength and strain of FRP-confined concrete using chaos control method

It is now well known that the confinement of concrete with fiber-reinforced polymer (FRP) composites can increase its strength and deformability. This paper presents a general nonlinear regression model to predict the ultimate conditions of FRP-confined concrete based on an iterative chaos control method (CCM). A dynamic chaos control factor is also proposed using the logistic map and a self-adaptive step size to achieve stabilization of the iterative chaos control method. To this end, a large database of axial compression tests on 769 circular FRP-confined concrete specimens was compiled from the published literature. Using the iterative method and the database, three nonlinear design-oriented models are developed and one of them is proposed for design applications. The results of this study show that the chaos control method can be successfully applied in the development of nonlinear models to predict the ultimate strength and strain of FRP-confined concrete.