Behaviour and design of cold-formed austenitic stainless steel circular tubes infilled with seawater sea-sand concrete

Abstract

Infilling seawater sea-sand concrete (SWSSC) into stainless steel tubes may be a feasible means of overcoming the shortage of fresh water and river sand in remote coastal areas. Herein, cold-formed austenitic stainless steel (CFASS) circular tubular stub columns infilled with SWSSC were tested. The CFASS tubes had 5 different cross-sections and the concrete mixes were of strength levels 35 and 70 MPa. Axial compression tests were carried out to study their structural behaviour in terms of load–strain curve, strength, ductility and failure mode. The test results revealed that the use of SWSSC in place of conventional concrete in stainless steel tubes has little effect on the structural behaviour and thus should be feasible. The test results were also compared with predictions by existing design equations in the codes and literature. It was found that the existing design equations are either un-conservative or overly conservative. Based on the test results in this study and those in literature, a new and more accurate design equation for axially loaded concrete-filled stainless steel circular tubular stub columns that is applicable to different types of concrete infill, including conventional concrete and SWSSC, was proposed.