철계-형상기억합금 스터럽으로 보강된 철근콘크리트 보의 전단거동

다국어 초록 (Multilingual Abstract)

This paper presents the experimental and analytical results of reinforced concrete beams reinforced with Fe-SMA stirrups to improve shear performance.
The specimen prepared for the experiment is 300mm wide, 500mm high, and 2,800mm long. The shear performance of the specimens reinforced with Fe-SMA stirrups was evaluated through a four-point load test. Experimental variables considered whether Fe-SMA was reinforced(non-reinforcement, reinforcement), reinforcement spacing(200mm, 300mm), and whether or not it was activated(non-activation, activation). Half of the specimen for shear behavior evaluation was fully reinforced with general rebar stirrup, and the other half was reinforced with Fe-SMA stirrup. As a result of the experiment, as the reinforcement spacing of Fe-SMA stirrup decreased, the shear crack height of the fully reinforced part increased, and the number of shear cracks decreased according to the activation of Fe-SMA. The ultimate load of the specimen with Fe-SMA stirrup spacing of 300mm, 200mm increased by 73% and 121%, respectively, compared to the ultimate load of the non-reinforced specimen. In addition, the ultimate load of the specimen increased by an average of 7.6% according to the Fe-SMA activation, and as a result of comparing the deflection at 500kN, the reinforcement spacing and activation decreased the deflection of the beam. This is considered to be because the transverse pre-constraint force of the reinforced concrete beam was applied by the activation of the Fe-SMA stirrup. Finite element analysis of specimens reinforced with Fe-SMA stirrups was performed through LS-DYNA, a commercial structural analysis program. As material models for finite element analysis, MAT_145, MAT_24, and MAT_4 models were used for concrete, reinforcing bars, and Fe-SMA stirrups, respectively. In this case, displacement control was used as the loading method of the analysis model.
In order to verify the reliability of the proposed finite element analysis model, a reproducible analysis of the experimental study conducted by Czaderski et al. was performed. As a result of the reproducible analysis, it was confirmed that the deflection and ultimate load showed low errors within 1% and 9.3%, respectively, compared to the experimental results.
Reproducible analysis of the experimental results of this study was performed using the proposed finite element analysis model. The ultimate load and ultimate deflection of the specimen derived through reproducible analysis showed relatively small errors of 1.8% and 9.5% on average from the experimental results. In addition, the proposed finite element analysis model realized the fracture shape of the specimen, the increase in stiffness, and the strain rate of the member relatively accurately. Therefore, it is thought that the finite element analysis model proposed in this study can be effecitely applied to predict the behavior of members reinforced with Fe-SMA stirrups. In addition, through the analysis of the experimental and analysis results, it was confirmed that shear reinforcement through Fe-SMA stirrup was effective in improving the usability of the member compared to the existing shear reinforcement.

목차 (Table of Contents)

• Ⅰ. 서 론 1
• 1.1 연구의 목적 및 필요성 1
• 1.2 연구 동향 4
• 1.2.1 국외 연구 동향 4
• 1.2.2 국내 연구 동향 6
• 1.3 연구 방법 및 범위 8
• Ⅱ. 형상기억합금 전단보강에 관한 기존연구 10
• 2.1 형상기억합금 10
• 2.1.1 형상기억원리 10
• 2.1.2 철계-형상기억합금 14
• 2.2 전단보강에 관한 기존거동 18
• 2.2.1 전단철근이 없는 보의 거동 18
• 2.2.2 전단철근이 적용된 보의 거동 21
• 2.2.3 철계-형상기억합금 스터럽이 적용된 보의 거동 22
• Ⅲ. 철계-형상기억합금 전단보강 실험 및 결과 24
• 3.1 개요 24
• 3.2 실험 계획 24
• 3.2.1 실험체 제원 및 변수 24
• 3.2.2 실험 재료 27
• 3.2.3 실험체 제작 32
• 3.3 하중재하 및 측정방법 32
• 3.4 실험 결과 및 분석 35
• 3.4.1 균열 및 파괴양상 37
• 3.4.2 보강 간격의 영향 39
• 3.4.3 활성화의 영향 43
• Ⅳ. 수치해석 45
• 4.1 해석모델 및 검증 45
• 4.1.1 재료모델 45
• 4.1.2 유한요소해석 모델링 50
• 4.1.3 유한요소해석 모델 검증 52
• 4.2 유한요소해석 결과 및 분석 56
• 4.2.1 파괴양상 56
• 4.2.2 하중-처짐 결과 59
• 4.2.3 하중-변형률 결과 65
• Ⅳ. 결 론 68
• 참고문헌 70
• 감사의 글 80