Hello there; You will get this warning if you have not defined a foundation when you should use the union between steel column and foundation. After defining the basis, the warning will go away. If you have defined between reinforced concrete column and steel column, the program does not consider the reinforced concrete column material in this version. In case the loading on it is pressure or pressure + bending, the concrete must be crushed. In this case, if the foundation is not defined or if the reinforced concrete column is defined, the concrete class is checked as C20. Good work.