The document compares the performance of a reinforced concrete (RCC) structure to a tube-in-tube structure through a parametric study. A 20-story building model was created in STAAD.Pro and ETABS to analyze each structural system. The tube-in-tube structure uses a central reinforced concrete core tube surrounded by perimeter columns and spandrel beams, acting as an outer tube. The study varied column depth, beam depth, and wall thickness to evaluate their effects on story drifts, base shear, and shear lag behavior between the two structural systems. Preliminary results found the column depth had a more prominent impact on the tube action and shear lag performance than other dimensions. Overall, the tube-in-