The application of modularized steel-concrete-steel sandwich composite structure (SCP) to the storage tanks installed at the polar or coastal regions is being considered because of their short construction time. However, design of SCP must be based on the application of existing design guidelines which require very close arrangement of shear studs. Densely arranged studs cause difficulty in pouring concrete during the manufacturing process and increase of production cost. This paper proposes an improved ratio of the stud spacing to the thickness of steel plate on the basis of numerous parametric studies to evaluate the relative influence of the stud spacing on the stability of the SCP.