Axial compressive behavior of circular concrete-filled steel tube stub columns prepared with spontaneous-combustion coal gangue aggregate

Abstract

The compressive behavior of circular concrete-filled steel tube (CFST) stub columns prepared with spontaneous-combustion coal gangue aggregate (SCGA) was investigated to study the effect of SCGA substitution level by experimental test and finite element simulation. The test variables included SCGA replacement ratios (0%, 50% and 100%) and steel ratios (8.3%, 11.6% and 14.2%). The study concerns the failure mode, ultimate compressive strength, elastic stiffness, ductility of the specimens, and the confinement effect of the steel tube. The test results showed that the failure mode of specimens prepared with SCGA was similar to that of reference CFSTs; compressive strength, elastic stiffness and ductility of the specimens were reduced by 2.93–4.81% (8.25–10.18%), −16.17–8.24% (3.01–22.16%) and 7.78–10.61% (11.86–16.34%) respectively with the increasing replacement ratio of SCGA from 0% to 50% (100%). A finite element model was proposed based on ABAQUS software and benchmarked against the test data from this study. The numerical results indicated that the SCGA replacement ratio and the confinement effect were the major factors of the compressive behavior of CFSTs. After comparing the test data with the existing design codes, modified design equations considering replacement ratio and confinement effects was proposed to predict the ultimate compressive strength of the specimens prepared with SCGA. Accuracy of the derived modified equation was evaluated, with the mean value of 0.984 and a standard deviation of 0.076. The study provides an experimental basis of the utilization of SCGA in CFST stub columns.