EXPERIMENTAL STUDY ON THE BEARING CAPACITY OF RECYCLED AGGREGATE CONCRETE-FILLED SQUARE STEEL TUBE SHORT COLUMNS UNDER AXIAL COMPRESSION

In order to study the bearing capacity of recycled aggregate concrete-filled square steel tube (RACFSST) short columns, 11 specimens with different recycled coarse aggregate replacement percentage are designed for axial compressive test. Test results indicate that the failure pattern of RACFSST short columns is the diagonal shear, which is similar to ordinary concrete-filled square steel tube short columns. The variation of recycled coarse aggregate replacement percentage does not obviously affect the bearing capacity of RACFSST short columns. According to the calculation and analysis of the ultimate bearing capacity of RACFSST short columns by Unified Strengthen theory and Superposition Calculation theory, the calculated values are both less than test values, so it is conservative. Economically, the calculation formulas proposed by Unified Strengthen theory can be applied to the design of RACFSST short columns. Finally, the stress-strain relationship of RACFSST short columns is proposed based on test data.