Hello! Thank you for reply sir AJA14. But there is still problem. When I modeled structural floor from "Model in place" tool as a stair, there is no option for analytical model. In other word even my stair becomes structural model it is not analytical so that I can't send it to the Robot Structural Analysis 2014 programm. I also used sloped floor and normal floor (structural) which represent a stair. Just maybe structures of sloped floor and normal floors could be similar to the structure of stair. But analytical nodes and lines of normal floor and sloped floor aren't connected each other. If I use sloped beam then the structure of stair will be completely different. I hope you will give me a comprehensive answer. That will be a very helpful for my project. Thank you.