In the case of columns in buildings with soft story, the concentration of stress due to the difference in stiffness can damage the columns. The irregularity of buildings including soft story requires retrofit because combined load of compression, bending, shear, and torsion acts on the structure. Concrete jacketing is advantageous in securing the strength and stiffness of existing members. However, the brittleness of concrete make it difficult to secure ductility to resist the large deformation, and the complicated construction process for integrity between the existing member and extended section reduces the constructability. In this study, two types of Steel Grid Reinforcement (SGR), which are Steel Wire Mesh (SWM) for integrity and Steel Fiber Non-Shrinkage Mortar (SFNM) for crack resistance are proposed. One reinforced concrete (RC) column with non-seismic details and two columns retrofitted with each different types of proposed method were manufactured. Seismic performance was analyzed for cyclic loading test in which a combined load of compression, bending, shear, and torsion was applied. As a result of the experiment, specimens retrofitted with proposed concrete jacketing method showed 862% of maximum load, 188% of maximum displacement and 1,324% of stiffness compared to non-retrofitted specimen.

Abstract
1. 서론
2. 단면증설공법의 상세 제안
3. 반복가력실험 계획
    3.1 시험체 상세
    3.2 가력 및 측정 상세
4. 실험 결과 및 분석
    4.1 균열 및 파괴양상
    4.2 최대하중 및 변위
    4.3 철근 변형률
    4.4 유효 강성
4. 결론
References

• 문홍비(경희대학교 건축공학과, 석사과정) | Moon Hong Bi (Department of Architecture engineering, Kyung Hee University)
• 이정인(경희대학교 건축공학과, 석사과정) | Lee Jeong In (Department of Architecture engineering, Kyung Hee University)
• 이영학(경희대학교 건축공학과 교수) | Lee Young Hak (Department of Architecture engineering, Kyung Hee University) Corresponding author