EXPERIMENTAL STUDY ON SELF-STRESSING SELF-COMPACTING AND HIGH-STRENGTH CONCRETE FILLED STEEL TUBULAR COLUMNS UNDER ECCENTRIC COMPRESSION

In order to improve the compactness of core concrete fills in steel tubes and reduce shrinkage which can ensure better composite action and meet project needs, twenty-one self-stressing self-compacting and high-strength concrete filled steel tubular columns and three self-compacting and high-strength concrete filled steel tubular columns were designed and tested under eccentric compression. The factors influencing the failure mode of specimens, namely slenderness ratio, eccentricity ratio and initial self-stressing, were investigated. The load-strain curves and load-column deflection curves were analyzed. The results showed that the eccentrically compressed specimens mainly demonstrate flexible buckling failure; the ultimate bearing capacity of the specimen decreases with the increase in load eccentricity ratio and slenderness ratio. The ultimate bearing capacity of the self-stressing and self-compacting concrete filled steel tubular columns can be improved by 9.2%~11.7% with initial self-stressing ranging between 3 to 5 MPa. Based on the relevant domestic design codes, a predictive equation for the ultimate bearing capacity of self-stressing self-compacting and high-strength concrete filled steel tubular columns was derived through regression analysis, and can serve as a reference for practical engineering design.