STUDY ON AXIAL COMPRESSION BEHAVIOR OF CA-UHPC FILLED STEEL TUBE STUB COLUMNS

In this study, 14 stub columns filled with ultra-high-performance concrete containing coarse aggregate (CA-UHPC) were prepared to study the axial compressive behaviors, in which the effects of steel fiber content, coarse aggregate substitution rate, and steel tube thickness were considered. The failure pattern, load-deformation curve, load-strain curve and bearing capacity of the specimens were investigated. The results show that: when the hoop coefficient falls within the range from 0.217 to 0.833, the specimens fail in a shear failure mode; while the coefficient range is from 0.883 to 1.43, the failure of specimens is mainly dominated by the drum damage. Moreover, in the case of the same steel pipe thickness, the incorporation of coarse aggregate can effectively improve the bearing capacity of the specimens. Based on the current concrete-filled steel tube specifications, a modified formula suitable for calculating the axial compression bearing capacity of CA-UHPCFST stub columns is put forward, which can be used as a reference for pertinent engineering design.