Experimental investigation on concrete-filled corrugated steel tubular column under constant axial load and cyclic load

Concrete-filled corrugated steel tubular (CFCST) structure is a novel composite member with significant potential serving as an offshore bridge pier or a sub-sea underground column. The anti-corrosive galvanized corrugated steel tube (CST) is versatilely utilized as a peripheral protecting shell, an external restraint material for the concrete, and a permanent formwork. A considerable body of preliminary experimental and numerical work has been conducted on the static performance of CFCST, however the investigations of its seismic behaviour are rather limited. This paper therefore presents experimental investigations on CFCST columns subjected to con-stant axial load and cyclic load. The designs and fabrications of the test setup are introduced in detail. With the discussion of failure modes, hysteretic curves, ductility, energy dissipation capacity, and stiffness degradation, the seismic behaviour of CFCST are studied comparatively. The test results indicate that the seismic behaviour of CFCST is more competitive than that of conventional RC columns while similar to those of TRC columns. With the increase of axial compression ratio, the lateral load was increased but the deformability was reduced. Both the strength and ductility of CFCST can be improved with the increase of confinement factor. The analysis of non-uniformly distributed strain of CST indicates that the loading paths do not affect the work mechanism of CST. The CST mainly provides transverse confinement and its contribution to flexural capacity was negligible. The modified equations can be roughly employed to predict the N -M interaction relationships of the CFCST columns. More experimental or numerical work should be conducted in the future to further evaluate the seismic behaviour of CFCST quantitatively.