go to define and analisecase,choose the modal and modifay it.you will see max number of modes make it five.
but there is important point.at least %90-95 of counstruction must join the analize.it can not be enough for high building.every time check it.
it can be taken 3 for each floor.by the way if your period too large.you can also see period 5 and other.go to display.and and show the deforme shape for modal,dead,and other loads...using arrows near the animation button you can arrive easly 5thperiod of bulding.
