You can make stairs from custom shapes too, check the help file. But with a number of arcs I guess it's easiest to create each arc individually. If you do a search in this forum (the
Search button above, between FAQ and Memberlist, not the Graphisoft search field) you will find a number of various ideas.
AC4.1-AC26SWE; MacOS13.5.1; MP5,1+MBP16,1