Experimental behaviour of concrete-filled double-skin corrugated steel tubes under combined compression and cyclic lateral loads

Concrete-filled double-skin corrugated steel tube (CFDCST), as a novel high-performance hollow section composite member, is formed by positioning thin-walled galvanized corrugated steel tubes (CSTs) at the outer and inner walls of hollow reinforced concrete. It is suitable for the application of piers, towers, and offshore platforms owing to the improved mechanical performance, corrosion resistance, and construction convenience due to the benefits provided by the CSTs. Based on the previous studies on its compressive behaviour, this paper further investigates its mechanical performance under combined compression and cyclic lateral loads. A total of 10 large-scale specimens were tested, with experimental variables of specimen types, axial compression ratios, hollow ratios, and outer CST thicknesses. The failure modes, hysteresis curves, key mechanical indicators, and strain distributions were discussed carefully. The experimental results indicated that the novel CFDCST specimens exhibited ductile flexural failure modes, and the hysteretic behaviour was significantly improved compared with the HRC specimens. Based on these analyses, the working mechanism was revealed and the specific design recommendations were proposed. Ultimately, two typical prediction models for similar members were modified and validated to predict the axial load–bending moment interaction diagram of CFDCST members.