This study proposes a refined joint shear strength model for exterior reinforced concrete beam-column connections with headed bars. A database consisting of 44 exterior reinforced concrete beam-column connection specimens with headed bars and exhibiting joint shear failure was established. The experimentally measured joint shear strengths were compared with predictions obtained from an existing model. The average ratio of experimental strength to model prediction was 0.775, indicating that the existing model generally overestimated the joint shear strength of connections with headed bars. Parameters associated with the headed bar anchorage requirements of ACI 318-25 showed no distinct relationship with the observed prediction errors. In contrast, parameters related to joint confinement and the embedment ratio of headed bars exhibited noticeable trends. Based on these observations, a refined joint shear strength model was proposed by modifying the exponent of the beam reinforcement index and introducing adjustment factors associated with joint transverse reinforcement and headed bar embedment. Application of the proposed model reduced the average prediction error from 22.5% to 1.6% and the coefficient of variation from 0.190 to 0.120.

Abstract
1. 서론
2. 기존 접합부 전단강도 모델
3. 데이터베이스 분석
    3.1 데이터베이스 구축
    3.2 기존 모델과 실험결과의 비교
    3.3 주요 변수 분석
4. 수정 접합부 전단강도 모델
5. 결론
감사의 글
References
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• 김재현(서울시립대학교 건축공학과, 박사후연구원, 공학박사) | Kim Jae Hyun (Dept. of Architectural Engineering, University of Seoul)
• 이윤정(서울시립대학교 건축공학과, 박사후연구원, 공학박사) | Lee Yoon Jung (Dept. of Architectural Engineering, University of Seoul)
• 주효은(서울시립대학교 건축공학과, 조교수, 공학박사) | Joo Hyo-Eun (Dept. of Architectural Engineering, University of Seoul)
• 한선진(충북대학교 건축공학과, 조교수, 공학박사) | Han Sun-Jin (Dept. of Architectural Engineering, Chungbuk National University)