Compressive behavior of CFRP-confined steel fiber-reinforced self-compacting lightweight aggregate concrete in square columns

Abstract

Self-compacting lightweight aggregate concrete (SLC) is greatly limited in the application of tensile and high-shear structures due to its obvious brittleness and low elastic modulus. Therefore, carbon fiber-reinforced polymer (CFRP)-confined steel fiber-reinforced self-compacting lightweight aggregate concrete (SFSLC) square columns were proposed, and axial compression tests were conducted in this paper. The effects of the steel fiber content, CFRP layers, and compressive strength grade of core concrete on the mechanical properties of SLC square columns were studied. According to the experimental phenomena and stress–strain curves, the synergistic effect of steel fiber and CFRP can obviously improve the failure mode and mechanical properties after peak stress. In contrast, the synergistic effect of the steel fiber and CFRP would be weakened by increasing the compressive strength grade of the core concrete. With the increase in steel fiber content, the deformability of the core concrete was improved, which increased the lateral confinement effect of the CFRP. When the number of CFRP layers was small, the mechanical properties of the specimens were significantly improved by adding a small number of steel fibers. With the increase in the number of CFRP layers, the reflection of internal defects caused by excessive steel fibers could be decreased. Based on the experimental study, the influence of variables on the confinement effect was analyzed, and the influence coefficient λ of steel fiber on the deformation of the specimen was introduced to establish the stress–strain curve models of CFRP-confined SFSLC square columns. Compared with the experimental curve, the model has higher prediction accuracy.