The Behaviour of Mortar Filled Double Skin Hollow Steel Columns

Abstract

Double Skin Hollow Mortar Filled Column (DSHMFC) is one of the composite columns that has been applied widely in civil engineering for its predominant mechanical behaviour. The hollow section in the column is to provide the space for service work such as piping and electrical conduit. These three specimens 300 mm DSHMFC columns were prepared with 65 mm, 75 mm, and 85 mm diameter of inner PVC tubes and 162.5 mm diameter of mild steel tube as outer skin. The study demonstrated the experimental investigation of DSHMFC acting as columns in compression with various diameters of the inner PVC tube. The space between the two skins was filled with mortar with a compressive strength of 42.5 MPa. The ultimate compressive load was determined in this study and compared with the theoretical values obtained from Eurocode 4. The relationship of diameter to thickness (D/t_c) ratio and the failure mechanism in DSHMFC were also observed in this study. The experimental results showed that the effective composite action of steel tubes and mortar increases the strength of DSHMFC by 95% compared to the hollow mild steel tubes. It was also observed that the failure mechanism of all the specimens was governed by local buckling. This study found the potential utilisation of PVC inner pipe as an alternative for steel in DSHMFC is feasible, especially in structures with moderate load conditions.