Axial compression behavior of circular high-strength self-compacting concrete-filled steel tubes with chloride corrosion

Concrete-filled steel tubes (CFSTs) are widely used as bridge piers in marine environments, where the outer steel tubes are highly susceptible to chloride corrosion, which degrades the carrying capacity of structural elements. This paper presents an experimental investigation on the axial compressive behavior of high-strength self-compacting concrete-filled steel tubes (HSSCCFST) with chloride corrosion. The study aims to determine the effects of steel ratio and corrosion rate on the behavior of steel plate and HSSCCFST columns subjected to chloride corrosion. The failure modes, load-displacement curves, load-strain relationship, carrying capacity, stiffness, ductility, confinement effect coefficient, strength index, and strength reduction factor are analyzed. The results show that the thicker the wall thickness of steel coupon, the more normal fracture occurs in the steel tensile coupons, the mechanical properties of steel coupons decrease as the corrosion rate increases. The axial compressive stiffness, ductility, residual ultimate strength factor of HSSCCFST decrease with the increase of corrosion rate, however, the impact of chloride corrosion deceases with the increase of steel ratio. Besides, the increase in corrosion rate weakens the composite action between the steel tube and the concrete core. A simplified formula of ultimate strength reduction factor considering corrosion rate and steel ratio is proposed, and CECS 104–99 is recommended to predict the ultimate strength of HSSCCFST stub column affected by chloride corrosion.