Ultimate seismic capacity of multi-story steel moment resisting frames having new column support system

In the seismic behaviors of the frames with fixed column bases, the soft story mechanism may occur when the frames are subjected to unexpected seismic horizontal force. This paper proposes the new columns support systems on the first story. The first story columns consist of the reinforced concrete downside column and the steel topside column, and their joints with the anchor bolts and the shear plates are supposed to be pinned. This paper clarifies the damage distribution and the seismic capacity for the steel moment resisting frames with these support system to perform the collapse mechanism which means the maximum story drift when the ductility demand reach the plastic deformation capacity for a member first.