Abstract: Different from conventional seismic design methods, seismic damping design method adds dampers in a structure which can dissipate input energy to control the structural seismic response. As a result, the member section sizes or the amount of reinforcement in the structure with dampers may be reduced from those without dampers. A series of reinforced concrete frame structures with nonlinear viscous fluid dampers as well as those ordinary frames without dampers are designed based on the current Chinese seismic design code for different seismic hazard levels. The seismic collapse-resistance capacity and safety margin of all these frames are calculated and compared through a collapse fragility analysis based on an incremental dynamic analysis approach. According to the results, a suggestion is proposed to enhance the collapse-resistance capacity of damping designed structures for high seismic hazard levels, and the effectiveness of the suggestion is verified.