Axial compression and bond behaviour of recycled aggregate concrete-filled stainless steel tubular stub columns

Abstract

This paper presents a series of axial compression and push-out tests on recycled aggregate concrete-filled stainless steel tube (RAC-FSST) stub columns. A total of 36 specimens were tested, including 18 circular columns and 18 square ones, to determine the effect of the confinement factor and the recycled aggregate replacement ratio on the axial compressive behaviour of these columns. The axial compression load versus longitudinal strain curves of tested columns demonstrated three trends as the confinement factor increased: post-peak softening, plasticity, and strengthening. Correspondingly, push-out slip tests of RAC-FSST members were conducted and formulas for bond strength were proposed. Generally, the bond strength of RAC-FSST was lower than that of CFST due to the smoother surface of the stainless steel tube and the larger shrinkage deformation of the core RAC. A finite element model was developed and verified for further analysis. Based on the experimental and numerical study, the structural behaviour of RAC-FSST was compared with that of normal CFST. The feasibility of existing formulas for axial compression strength calculation of RAC-FSST was evaluated. Based on the collected experimental results of RAC-FSST stub columns and the statistical parameters of the strength for stainless steel tube, reliability analysis was carried out. The partial factors of axial compressive strength of RAC-FSST in building structures, highway bridges, and port engineering structures were proposed.