Reinforced concrete tall buildings with central shear core systems are widely used due to their high lateral stiffness and satisfactory seismic performance. However, geometric irregularities, torsional effects, and increased deformation demands under near-fault earthquakes may significantly affect their structural response. This study investigates the effectiveness of shape memory alloys (SMAs) in improving the seismic and torsional performance of 15-story reinforced concrete buildings with central shear core systems. Two building models with regular and irregular plan configurations were analyzed using three reinforcement layouts: conventional steel reinforcement, targeted use of SMA bars in the longitudinal reinforcement of boundary elements, and full replacement of longitudinal reinforcement with SMA bars in the shear walls. Nonlinear time-history analyses were carried out in SeismoStruct using near-fault earthquake records. The results showed that the use of SMA reduced interstory drift and improved torsional behavior compared with the conventional steel-reinforced configuration. In the regular-plan model, the maximum torsional ratio decreased from 1.42 to 1.11, while in the irregular-plan model it decreased from 1.66 to 1.33 and further to 1.25 when SMA was used throughout the shear wall reinforcement. The observed reduction in torsional ratio and interstory drift can be attributed to the superelastic and self-centering characteristics of SMA. Furthermore, the targeted use of SMA in the boundary elements, while requiring less SMA than the fully reinforced configuration, provided considerable improvement in the seismic performance indices of the investigated models.