Axial Compression Behavior of Recycled Concrete Filled Steel Tubular Short Columns after High Temperature

This article is devoted to study the axial compression behaviour of recycled concrete-filled steel tubular (RCFST) columns after high temperature. Several axial compression members’ internal mechanisms are analyzed by combining experimental and finite element analysis (FEA). Firstly, the failure mode of axial compression members is studied by experiments. Then, based on the correct constitutive relationship between recycled concrete and steel, the finite element model is established by ABAQUS software, and theoretical analysis and experimental verification are carried out, which are in good agreement. The effects of different parameters such as temperature, substitution rate, and bond strength of the coefficient on the whole load-strain curve are compared. The results show that the bearing capacity of recycled concrete-filled steel tubular columns decreases with the increase in temperature and replacement rate. The bond coefficient between steel tubular and core concrete has little effect on the specimen’s overall axial compressive mechanical properties. The interaction force P rises slightly along the height after the high temperature at the peak load, as it gradually moves away from the cover. In the square section, corners show stress concentration, and bulge deformation occurs first under the condition of axial compression.

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