This study investigates the seismic performance of a hybrid seismic energy dissipation device composed of a viscoelastic damper and a steel slit damper connected in parallel. A moment-framed structure is designed without seismic load and is retrofitted with the hybrid dampers. The model structure is transformed into an equivalent simplified system to find out optimum story-wise damper distribution pattern using genetic algorithm. The effectiveness of the hybrid damper is investigated by fragility analysis of the structure with and without the dampers. The analysis results show that after seismic retrofit the probability of reaching damage states, especially the complete damage state, of the structure turn out to be significantly reduced.

ABSTRACT
 1. Introduction
 2. Hybrid dampers used in the analysis
 3. Seismic retrofit of analysis model structures
 4. Optimum distribution of hybrid dampers forseismic retrofit
 5. Failure probability of the model structure
 6. Conclusion
 REFERENCES

• 김민성(성균관대학교 건설환경공학부) | Kim Minsung (Department of Civil and Architectural Engineering, Sungkyunkwan University)
• 자오동쉬(동남대학교 토목공학과) | Xu Zhaodong (Department of Civil Engineering, Southeast University)
• 김진구(성균관대학교 건설환경공학부) | Kim Jinkoo (Department of Civil and Architectural Engineering, Sungkyunkwan University) Corresponding author