Performance degradation of circular thin-walled CFST stub columns in high-latitude offshore region

Abstract

Abstract This paper presents an investigation on the performance degradation of circular thin-walled concrete-filled steel tubular stub columns in the high-latitude offshore region. 24 specimens were loaded axially after freeze-thaw cycles and salt spray corrosion. The results show that with the increase of corrosion rate and concrete grade, the strength degradation of the specimens after the peak point becomes severe. The increase of corrosion rate approximately linearly reduces the ultimate strength of the specimens after freeze-thaw cycles, regardless of concrete grade. The ductility index and the composite elastic modulus of the circular thin-walled CFST stubs are decreased by corrosion after freeze-thaw cycles. Two design methods are proposed based on the discussions of the test results. The simplified design method for predicting the ultimate strength is proposed and validated based on the test results. The design method in Eurocode 4 for the ultimate strength is improved, in terms of material property degradation. A full-range prediction of the strength degradation of circular thin-walled CFST stubs under freeze-thaw cycles and corrosion is conducted. It is concluded that the high strength of core concrete is beneficial for the duration ability of thin-walled CFST stub columns.