The steel double-beam floor system is capable of reducing the construction period due to the weight reduction of the unit members compared to the general rigid-frame steel structure, thereby reducing the indirect construction cost due to the improvement of constructability. However, there is also a problem with the construction management caused by the increase in the number of members. Therefore, in this study, we will apply a combination of different spans of steel double-beam floor systems, to analyze the economic and story-reduction effects, and propose an optimal structural frame.