Hello, we want to build a steel floor on a 4-storey reinforced concrete building. When I do this; 1- Should we remodel the existing building and add the steel floor? 2- Steel buildings made from scratch are explained, including training videos. There are structures that have a foundation when they are built from scratch. When adding a steel floor, we introduce the program to how this will be done on an existing structure. 3- If we are going to model the steel floor alone and the force, load etc. coming from it. If we are going to check whether the existing structure can carry or not, a situation arises. That the steel structure on the 5th floor of the existing building may differ only according to the modeled structure, especially its behavior against earthquakes? I would like your help regarding the path I should follow.