To investigate the hysteretic behaviour of an eccentrically loaded partially-concrete-filled steel tubular (PCFST) bridge pier in an out-of-plane horizontal direction, a quasi-static experiment and finite element (FE) analysis of steel tubular columns were carried out. In this study, four PCFST column specimens were tested under constant eccentrically loaded and out-of-plane horizontal cyclic loading. The elasto-plastic behaviour and failure mode of these specimens were investigated. Secondly, the FE models of these four experimental PCFST columns were established, through comparisons with the experimental results, the validity of the selected elements, mesh division, the contact relationship between the concrete and the steel pipe, and the boundary conditions of FE models were verified. Thirdly, 30 FE models of PCFST bridge piers were analyzed to ascertain the effects of slenderness ratio λ, radius-thickness ratio Rt, and vertical load eccentricity ratio e/L on ultimate strength and ductility. Finally, an empirical formula was proposed to describe the ultimate strength and ductility of such bridge piers for engineering application under complicated loading conditions.