Nonlinear Regression Prediction of Mechanical Properties for SMA-Confined Concrete Cylindrical Specimens

In order to achieve active confinement in concrete elements, researchers have recently employed smart materials called shape memory alloys (SMA). Several empirical relationships been widely used predict the behavior of confined concrete. To develop more accurate relations for predicting actively with SMA spirals, it is necessary obtain new determining peak compressive stress and corresponding strain addition ultimate strain. For this purpose, existing data from 42 specimens plain cylindrical spirals subjected uniaxial compression were collected. Then, by using MATLAB SigmaPlot software, nonlinear regression analyses conducted optimum relations. The best equations selected multiple error criteria root mean square (RMSE) R-squared (R2). Finally, accuracy proposed was compared which showed better accuracy.