Abstract:A comparative study was made of the vibration performances of frame structures without stair tread,with straight stair tread or with folded stair tread by ANSYS numerical simulation.The stair with folded slab was proposed to adopt while designing stair in frame structure.Landing board and frame column were proposed to be separated as well.With the method,the K-effect of stairs during earthquake would be weakened and the stairs’ capability to take part in the whole structure decreases,too.The mal-distribution of seismic force among frames would be lightened.As a result,the internal force of the stair components and the difficulty of design would diminish.However,frame columns would not be changed into short columns.Meanwhile,the conservative degree of allowable value of drift angle would be reduced.Based on a lot of data,the variation law of stress was investigated,and proposals on dimensions of folded stair were put forward.