Deformations of a plastic tube with concrete-infill under direct load

Abstract

Confinement of concrete columns can be an effective means of enhancing structural members' deformation—alternative materials such as uPVC tube show elastic-plastic behavior with considerable elongations at failure. The material ductility features significant deformations that usually considered to be belonging to the set of mechanical properties. The tube can be applied for encasing concrete, thereby influencing the deformability capacity of a column. The current work aims to evaluate the axial strain of plastic tubes with concrete-infill (PTCI) specimens tested under uniaxial compression load. A strain model was developed for PTCI specimens using a normalized confinement stiffness procedure, based on a database of experimental results from recent studies 2019-2020 and those of the present study. Five existing FRP-confined concrete models and the developed model were employed to predict PTCI columns' strain, and the predictions were compared with experimental results in the database. Three statistical indexes were used to evaluate the proposed and the three existing FRP-confined concrete strain models' performance. The indexes included: Average absolute relative error (AAE), Normalized root-mean-square error (NRMSE), and coefficient of correlation (R2). The comparison shows the proposed model to give more close prediction to the experimental test data and the comprehensive database to yield the lowest average absolute error (AAE). The root means square error (RMSE) compared with other models in the present study.