Recent earthquakes (2016 Gyeongju and 2017 Pohang) revealed the seismic vulnerability of existing non-seismicallydetailed reinforced concrete (RC) school buildings in Korea. This study proposes and experimentally verifies an CFT-column seismic retrofit method, in which concrete-filled steel tube (CFT) columns are anchored to existing RC columns and connected by a steel beam at the column mid-height. To examine the effect of infilling the CFT columns, three full-detail specimens—non-retrofitted (NRF), mortar-filled retrofitted (IFRF), and unfilled retrofitted (IERF)—were fabricated based on 1980s non-seismic school-building details and tested under displacement-controlled cyclic loading. The hysteretic behavior, strength, stiffness, energy dissipation, and failure modes were compared, and the envelope curves were idealized using the equivalent energy elastic-plastic (EEEP) model. Relative to NRF, the retrofitted specimens showed about 3.3 times higher effective stiffness, 3.3–3.5 times higher strength, ductility increasing from 2.07 to 2.99–3.20, and 742–815% higher energy dissipation.

Abstract
1. 서론
    1.1 연구의 배경 및 목적
2. 실험체 개요 및 실험방법
    2.1 실험체 개요
    2.2 실험체 계획
    2.2 실험 방법
    2.3 가력 계획
    2.4 실험 셋업 및 계측계획
3. 실험결과 및 내진성능 비교
    3.1 하중-변위 이력거동
    3.2 등가에너지 탄소성(EEEP)이선형 이상화
    3.3 에너지소산능력
    3.4 파괴모드
4. 결론
감사의 글
References

• 신승훈(한국해양대학교 일반대학원 해양건축공학과, 박사과정) | Shin Seung-Hun (Department of Oceanic Architectural Engineering, Korea Maritime & Ocean University) Corresponding author
• 오지훈(㈜힐엔지니어링 부장, 공학사) | Oh Ji-Hoon (Senior Manager, Hill Engineering Co., Ltd.,)
• 우종열(㈜힐엔지니어링 대표이사, 공학박사) | Woo Jong-Yeol (President & CEO, Hill Engineering Co., Ltd.,)
• 박수용(한국해양대학교 해양건축공학과 교수, 공학박사) | Park Soo-Yong (Department of Oceanic Architectural Engineering, Korea Maritime & Ocean University)