Hybrid B-CSM Composites Strengthening Approach for Improved Stress–Strain Behavior of Concrete Columns and Development of Analytical Models

Abstract

The brittle behavior of concrete under axial compressive loading has been a persistent issue. This study investigates the effectiveness of a hybrid Basalt-E-glass confinement (B-CSM) in improving the compressive behavior of concrete. The B-CSM confinement demonstrates a considerable improvement in ultimate strength and strain capacity by over 250 and 500%, respectively, making it a favorable solution for enhancing the ductility of concrete structures. Specimens at 18.43 MPa unconfined strength, confined with 3-layer B-CSM, demonstrated a 258% ultimate strength enhancement. For 24.43 MPa specimens, the same confinement resulted in a 207% increase in ultimate strength. Specimens with an initial ultimate strain of 18.43 MPa, when confined with 3-layers, showed a notable 516% increase. Likewise, for 24.43 MPa specimens, the same confinement led to a significant 395% improvement in ultimate strain. The use of B-CSM confinement is also effective in terms of cost compared to synthetic fiber-reinforced polymer jackets, and its availability is widespread. Existing analytical models for fiber-reinforced polymer confinement were evaluated, and it was found that these models could not predict the ultimate strength and strain of B-CSM-confined concrete. Therefore, this study proposes a unique regression-based approach for predicting the various points of the compressive stress vs. strain curve of B-CSM confinement. These points are then used to trace the complete stress vs. strain curve, which matches closely with experimental results. This work contributes to the development of new design recommendations for B-CSM confined concrete structures, which can enhance the performance of concrete structures and potentially reduce construction costs.