The confinement ratio of spun piles manufactured in Indonesia has been a matter of concern since it does not meet the applicable requirements. Additional steel jacketing retrofitting was used to cope with the problem as well as improve the strength of spun pile to pile cap connection. A numerical study was performed to study the effect of steel jacketing on a spun pile with concrete infill reinforcement. Furthermore, a parametric study was conducted to study the effect of steel jacketing length to spun pile behaviour. Pushover analysis using the Opensees software will be performed with a monotonic loading approach. The results were compared in terms of load - displacement curve, shear and bending capacity, and displacement ductility. It is found that the presence of steel jacketing provides a better behaviour and significantly increases the ductility of specimens. The study also found that a minimum length 1.5D of steel jacketing retrofitting was necessary for better results and remain easily repairable for future concerns. © Published under licence by IOP Publishing Ltd.