Hello Mr. Hakan, there are 2 projects that I use for my thesis work, these are the same projects. The natural period, which is 0.57 in 5 versions, turns out to be 0.80 in 6 versions, so all cross-section effects are different. Does it prepare data for sap 2000 ver 11 and later in version 6? By the way, in 6 versions, the concrete class is selected when entering the first project, but I could not find a place to assign a new concrete class afterwards. In the options, there are only the concrete types that I entered when entering the first project. Take it easy Suat Yildirim