Finite element analysis and bearing capacity of CRACFDSST columns under eccentric compression

The mechanical behaviour of ceramic recycled aggregate concrete-filled double-skin square steel tubular (CRACFDSST) columns under eccentric compression, with changing slenderness ratio, eccentricity and hollow section ratio parameters, was investigated, and 12 columns were tested. The test results indicated that all specimens exhibited elastic-plastic instability failure. No cement-based materials attached to the ceramic glaze surface were observed at the crushed position. Additionally, the CRACFDSST columns had good ductility and bearing capacity. The constitutive relationship of ceramic recycled concrete constrained by the square steel tube was adopted to establish finite element (FE) models, which considered the plastic damage of concrete. The FE calculation results agreed well with the experimental results. FE analyses of ceramic recycled concrete and ordinary concrete members were conducted, and the stress distributions of the steel tubes and concrete, the load-deflection curves at the mid-span, and the interaction between the steel tubes and concrete of the members were compared. Subsequently, 312 FE examples were used to analyse the effects of the steel yield strength, concrete strength, hollow section ratio, nominal steel ratio, diameter-to-thickness ratio of the inner steel tube, slenderness ratio and ceramic coarse aggregate replacement rate on the moment-load curves. Ultimately, a simplified formula was proposed to predict the bearing capacity of CRACFDSST columns under eccentric compression.