Axial Load-carrying Capacity of Steel Tubed Concrete Short Columns Confined with Advanced FRP Composites

Abstract

Fiber Reinforced Polymers (FRPs) have wide applications in the field of concrete construction due to their superior performance over conventional materials. This research focuses on the structural behavior of steel tube FRP jacket–confined concrete (STFC) columns under axial concentric loading and proposes a new empirical equation for predicting the axial load-carrying capacity of STFC columns having thickness of FRP-fabric ranging from 0.09 mm to 5.9 mm. A large database of 700 FRP-confined concrete specimens is developed with the detailed information of critical parameters, i.e. elastic modulus of FRPs (Ef), compressive strength of unconfined concrete (fc’o), diameter of specimen (D), height of specimen (H), total thickness of FRPs (N.tf), and the ultimate strength of confined concrete (fc’c). After the preliminary evaluation of constructed database, a new empirical model is proposed for the prediction of axial compressive strength of FRP-confined specimens using general regression analysis by minimizing the error functions such as root mean squared error (RMSE) and coefficient of determination (R2). The proposed FRP-confinement strength model presented higher accuracy as compared with previously proposed models. Finally, an equation is proposed for the predictions of axial load carrying capacity of STFC columns. For the validation of proposed equation, an extensive parametric study is performed using the proposed nonlinear finite element model (FEM). The FEM is calibrated using the load-deflection results of STFC columns from literature. A close agreement was observed between the predictions of proposed finite element model and proposed capacity equation.