Expressions for limiting vertical forces acting on beam-columns and beams were proposed first in order to control the cumulative damage of steel frames. The expressions were derived from a condition for stopping the progress of cumulative damage in frames. To verify the validity of the proposed expressions, one-story and two-story steel frames were analyzed by finite element method. Analytical results show that the proposed expressions are useful for controlling the cumulative damage of steel frames subjected to a repeated horizontal loading such as a seismic force. In addition to that, a design method of separating structural elements supporting a vertical force and those resisting a horizontal force is proposed to control the cumulative damage of frames. Some prototype steel frame models designed by the method are analyzed numerically, and the resisting performance and the stability of the frames with the accumulation of damage are discussed.
