PURPOSES : When fire event occurs in tunnel the reinforced concrete is exposed to very high temperature at a very short time period. This study investigates the tensile behavior of steel rebar that experienced high temperature.
METHODS : The steel rebar was exposed to 200, 400, 600, and 800℃ following the ISO 834 temperature-time fire curve. Hightemperature- exposed steel rebars were tested using the UTM for their yielding and tensile strengths, and elongation rate.
RESULTS : Up to an exposure temperature of 600℃, the tensile properties of the rebar did not vary considerably. However, at 800℃ (which corresponds to a temperature rise time of approximately 22 min), the rebar lost its yielding and tensile strength by approximately 27 and 13%, respectively, compared to the control specimen. Further, the elongation rate increased after exposure to 600℃. The above fundamental tensile test results can be a good reference for future guidelines in the repair manual for tunnels after severe fire events.
CONCLUSIONS : When steel rebar experiences high temperatures of 800℃, the yield strength of the rebar reduces approximately 27%. This strength reduction can cause severe structural damage to tunnels that use reinforced concrete as the primary structural elements.

ABSTRACT
1. 서론
    1.1. 연구의 배경 및 목적
2. 철근의 고온 노출 시 특성
3. 실험재료 및 실험방법
    3.1. 철근
    3.2. 화재 온도 곡선
    3.3. 내화로
    3.4. 인장강도 및 변형률 실험
4. 실험 결과 및 분석
    4.1. 변수별 응력변형률 곡선
    4.2. 변수별 연신율 거동
5. 결론
감사의 글
REFERENCES

• 최승원(강원대학교 토목건설공학과 석사과정) | Choi Seungwon
• 장태진(강원대학교 건설융합공학과 박사과정) | Jang Taejin
• 주민규(강원대학교 건설융합공학과 박사과정) | Ju Minkyu
• 심재원(한국도로공사 도로교통연구원 안전혁신연구실 연구위원) | Shim Jaewon
• 김승원(강원대학교 건설융합학부 토목공학전공 조교수) | Kim Seungwon
• 박철우(강원대학교 건설융합공학과 박사과정) | Park Cheolwoo Corresponding Author