• For the moment resisting frames with fixed column bases, the soft story mechanism may occur during earthquake due to become plastic hinges at the bottom part of columns. This paper proposes the new support system on the first story whose 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. It is possible for the frames with this support system to uniform the magnitude of the bending moment at column top and base, and to perform beam yielding mechanism for 6 and 9 story frames with 2.1 of the column-to-beam full plastic moment ratio.

In this column support system, the 1st story column consists of steel topside column and reinforced concrete downside column, whose connection at the midstory performs as a pin.
As the results, the steel moment resisting buildings with the new support system is capable to prevent the soft story mechanism on the first story, and beam-yielding mechanism is high likely performed.
In addition, application of the system facilitates construction of the buildings, compared to those supported by embedded base, and reduces construction cost.

• Steel Moment Resisting Frames
• Beam Yielding Mechanism
• Damage Concentration
• Plastic Deformation Capacity
• Column Support System