Compressive Behavior of Large-Rupture-Strain FRP-Confined ECC Cylinders under Eccentric Loading

Abstract

Fiber-reinforced polymer (FRP)-confined engineered cementitious composite (ECC) cylinders offer ductility and energy dissipation, yet their behavior under eccentric loading remains unexamined. To address this, this study investigates the mechanical performance and failure mechanisms of 64 ECC specimens with a diameter of 150 mm and a height of 300 mm confined with traditional glass FRP (GFRP) and large-rupture-strain (LRS) FRP under eccentric compression. The variables that were considered were the concrete type (normal concrete and ECCs), FRP type (LRS FRP and GFRP), load eccentricity (0, 10, 30, and 50 mm), and the number of FRP layers (0, 2, 3, and 4). The results showed that ultimate load capacity, axial deformation, and energy dissipation capacity increased with an increase in FRP layers, irrespective of eccentricities. However, these values decreased with increasing eccentricities. Eccentric loading resulted in a nonuniform distribution of FRP hoop strains, with a gradual increase from the tension side to the compression side. The applicability of existing confinement models to predict the axial load—bending moment ( N − M ) interaction diagrams of FRP-confined ECC cylinders in eccentric loadings was also examined. It was found that the N − M interaction diagram developed using existing FRP-confined ECC models agreed well with the experimental counterparts under eccentric loading. An analysis was conducted to investigate the effects of the compressive strength of the ECC, the number of FRP layers, and the FRP rupture strain on the N − M interaction diagram, providing a theoretical foundation for their design and implementation in practical engineering.