<p>This study presents a novel method for developing a finite element (FE) model of partially encased composite (PEC) columns within the ABAQUS/Standard module, alongside a proposed compressive stress–strain relationship specifically for confined concrete. The proposed FE model’s accuracy was corroborated through comparison with existing experimental datasets from both monotonic and cyclic loading tests. Comparative assessments demonstrated that, in contrast to conventional concrete constitutive models, the FE model incorporating the proposed concrete constitutive relation achieved more accurate simulations of PEC column behavior. Additionally, a parametric investigation was performed on PEC columns subjected to cyclic loading to examine the effects of axial compression ratio and structural measures on their seismic performance. The results revealed that the inclusion of transverse links, longitudinal reinforcement, and stirrups effectively enhanced the load-bearing capacity and deformation capacity of the specimens. With an increase in the axial compression ratio, the distance from the most unfavorable section of the specimen to the bottom gradually increased. Under high axial compression ratios, special attention should be paid to the risk of the most unfavorable section shifting into the non-dense region of transverse links, where confinement effectiveness is compromised.</p>