Axial compression behavior of basalt fiber‐reinforced recycled aggregate concrete‐filled square steel tubular stub column

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Abstract
This study aimed to determine the mechanical properties of the basalt fiber‐reinforced recycled aggregate concrete (BFRRAC)‐filled square steel tubular stub columns under axial compression. The replacement ratio of recycled coarse aggregate, the content of basalt fiber, and the strength grade of the BFRRAC were designed as the variable parameters, seven BFRRAC‐filled square steel tubular stub columns were designed and subjected to axial compression tests. The failure process and morphologies of the specimens were observed, the load–displacement/strain curves were measured, and the influence rule of variable parameters on the axial compression performance indexes, such as peak bearing capacity, energy dissipation capacity, and ductility coefficient, was discussed. Based on the degradation law of combined secant‐stiffness under axial compression, a piecewise mathematical model of stiffness degradation was established. The parametric influence factor was introduced into the design, and the axial compressive stress–strain curve equation was established. Results show that the local bulging failure of all specimens belongs to the category of strength failure. The working process of BFRRAC‐filled square steel tubular stub column under axial compression can be divided into three stages: elastic, elastic–plastic, and plasticity. With the increase in the replacement ratio of recycled coarse aggregate, the peak bearing capacity and ductility of specimens were finally weakened, and the energy dissipation capacity first increased and then decreased. With the increase in BFRRAC strength grade, the peak bearing capacity and energy dissipation capacity of the specimens increased while ductility decreased. The addition of a certain amount of basalt fiber has a little effect on the peak‐bearing capacity of the specimen, but can improve its energy dissipation capacity and ductility.
Funding Information
  • National Natural Science Foundation of China (U1904188)

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