Axial compressive behavior of spontaneous‐combustion coal gangue square concrete‐filled steel tube columns with diagonal ribs

This study investigated the axial mechanical properties of diagonal‐ribbed square concrete‐filled steel tubular (CFST) columns incorporating spontaneous‐combustion coal gangue aggregates (SCGAs). Failure modes, ultimate load‐carrying capacity, load–displacement response, elastic stiffness, and ductility coefficient were examined for different SCGA replacement ratios and rib configurations. The experimental results indicated that the mechanical performance of the columns decreased with increasing SCGA replacement ratio. For specimens with identical steel contents and SCGA replacement ratios, the diagonal‐ribbed columns exhibited a more favorable axial mechanical response than the double‐longitudinal‐rib columns. A finite element (FE) model was developed in ABAQUS to assess the effects of SCGA replacement ratio, concrete strength, steel tube thickness, column side length, and rib plate thickness. The FE model reproduced the axial compression performance of diagonal‐ribbed square CFST columns incorporating SCGA with satisfactory accuracy. Existing ultimate load‐carrying capacity prediction models were modified, and the revised model improved the prediction accuracy for diagonal‐ribbed square CFST columns.