ÜNVER, THANK YOU FOR YOUR HELP BUT WHAT IS THE PURPOSE OF UPGRADING THE LEVEL OF DUCTILITY WHEN WE SOLVED IT WITH THE MIXED SYSTEM, WE DIDN'T GET R ERRORS WHEN WE DIDN'T GET THE R ERRORS. quote] We were not getting the (B) errors. If you increase the ductility level higher, the horizontal forces will affect the building less because the horizontal forces are divided by a larger coefficient. In this case, if the (B) errors occur, you need to correct them. (B) control is not done in hash and limited. These situations are at the initiative of the engineer within the constraints. When choosing, I choose by paying attention to the high-mixed-limited order. (The program wizard also directs from high to limited.) Above. In the high-mixed-limited situation, even if there is no problem in balancing in the structure, tipping can be It may not be enough in one of them. I think it is necessary to decide on the ductility level by controlling these situations. Read the information and discussion threads on the forum about 4/5R. Unver ÖZCAN