Axial compression behaviors of reinforced sea-sand concrete-filled circular stainless steel tubular stub columns

Owing to their exceptional durability and lower total life-cycle cost, reinforced sea-sand concrete-filled (circular) stainless steel tubular (RSCFSST) columns offer a highly viable structural solution for coastal regions. To investigate the effects of stirrup spacing and concrete type on the axial compression properties of circular RSCFSST columns, eight axial compression tests were conducted on three types of specimens: circular RSCFSST short columns, reinforced normal concrete-filled stainless steel tubular counterparts, and sea-sand concrete-filled stainless steel tubular (SCFSST) counterparts. The test results indicated that the use of sea-sand concrete has minimal influence on the axial compression behavior of the circular RSCFSST column. Furthermore, the circular RSCFSST columns exhibited superior compression resistance and ductility compared to their SCFSST counterparts. Subsequently, a finite element (FE) model of the circular RSCFSST column was developed to perform mechanism and parametric analyses. Mechanism analysis highlighted that the confinement provided by stainless steel stirrups significantly enhances both the bearing capacity and ductility of core concrete. The parametric analysis further indicated that their axial compression resistance increases with increasing concrete compressive strength, steel yield strength, steel tubular ratio, or volumetric stirrup ratio. Based on these findings, new simplified models to forecast the axial compression resistance, axial compression stiffness, and peak strains of circular RSCFSST columns were suggested.