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Research Article

Failure Behavior of Extremely Under-reinforced Concrete Beams and Minimum Steel Ratio of Flexural Members

극 저보강 철근콘크리트 보의 파괴거동과 휨부재의 최소 철근비

Jae-Hoon Lee1*
,
Dong-Hyun Kim2
,
Hyeong-Yeon Kim3
이 재훈1*
,
김 동현2
,
김 형연3
1Professor, Department of Civil Engineering, Yeungnam University, Gyeongsan 35841, Korea
2Engineer, Department of Structural Engineering, TAE SUNG Engineering Consultants Co., Ltd., Hanam 12930, Korea
3Senior Student, Department of Civil Engineering, Yeungnam University, Gyeongsan 35841, Korea
1영남대학교 건설시스템공학과 교수
2태성종합기술 구조부 사원
3영남대학교 건설시스템공학과 학생
*Corresponding Author
31 December 2024. pp. 109-119
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Abstract

In this study, failure behavior of 12 reinforced concrete beams of four sizes with a very small amount of steel reinforcement was observed, and the safety of the minimum steel amount provisions in three design codes were investigated. From the experiment, it was confirmed that the member with too little steel reinforcement did not exhibit flexural strength beyond cracking moment. And also, it was found that the minimum steel regulation for flexural members in the KDS 14 20 20 Korean design code provided conservative results compared to the experimental results. However, further investigate is needed to determine whether the regulation is sufficiently conservative for the actual concrete structures. The ACI 318-19 design code regulation provided more conservative results than the KDS 14 20 20 code regulation did. The minimum reinforcement regulation of the KDS 24 14 21 Korean concrete bridge design code showed very low safety. Therefore, a modified regulation of minimum steel requirement for the KDS 24 14 21 design code was proposed to improve the safety.

Keywords
flexural members
failure behavior
cracking moment
flexural strength
minimum steel of the design code

이 연구에서는 매우 적은 양의 인장철근을 배치한 네 가지 크기의 보 12개를 제작하고 재하실험을 통하여 파괴거동을 관찰하였으며, 실험결과를 바탕으로 설계기준의 최소 철근량 규정의 안전성을 분석하였다. 실험결과 너무 적은 양의 인장철근이 배치된 부재는 균열휨모멘트 이상의 휨강도를 발휘하지 못함을 확인하였다. 이 실험연구의 경우 휨부재에 대한 KDS 14 20 20 설계기준의 최소 철근 규정이 실험결과에 비하여 보수적인 결과를 제공하였지만, 실제 구조물에 대해서도 충분히 보수적인지는 추가의 검토가 필요할 것이다. ACI 318-19 설계기준의 최소 철근 규정은 KDS 14 20 20 설계기준보다 더 보수적인 결과를 제공하였다. KDS 24 14 21 콘크리트교 설계기준의 최소 철근 규정은 매우 낮은 안전율을 나타내었다. 따라서 이 연구에서는 안전율을 확보하기 위하여 KDS 24 14 21 설계기준의 최소 철근 규정의 수정안을 제시하였다.

키워드
휨부재
파괴 거동
균열휨모멘트
휨강도
설계기준의 최소 철근비
References
1

ACI Committee 318 (2019) Building Code Requirements for Structural Concrete (ACI 318-19) and Commentary. Farmington Hills, MI; American Concrete Institute (ACI).

2

ASTM (2022a) Standard Specification for Deformed and Plain Carbon-Steel Bars for Concrete Reinforcement (ASTM A615/A615M), USA, American Society for Testing and Materials (ASTM)

3

ASTM (2022b) Standard Specification for Low-Alloy Steel Deformed and Plain Bars for Concrete Reinforcement (ASTM A706/A706M), USA, American Society for Testing and Materials (ASTM)

4

CEN (2004) Eurocode 2: Design of Concrete Structures - Part 1-1: General Rules and Rules for Buildings (BS EN 1992-1 : 2004), London, UK; European Committee for Standardization (CEN), British Standards Institute (BSI).

5

KATS (Korea Agency for Technology and Standards) (2021) Steel Bars for Concrete Reinforcement (KS D 3504), Seoul, Korea. (In Korean)

6

KCI (Korea Concrete Institute) (2022) Flexure and Axial Compression (KDS 14 20 20), Structural Concrete Design Code and Commentary. Seoul, Korea: KCI. (In Korean)

7

KCI (Korea Concrete Institute) (2021) Serviceability (KDS 14 20 30), Structural Concrete Design Code and Commentary. Seoul, Korea: KCI. (In Korean)

8

KEA (Korea Electric Association) (2010) KEPIC (Korea Electric Power Industry Code) Nuclear Safety Related Structures, SNB Concrete Containments. Seoul, Korea. (In Korean)

9

KEA (Korea Electric Association) (2015) KEPIC (Korea Electric Power Industry Code) Nuclear Safety Related Structures, SNC Nuclear Safety-Related Concrete Structures. Seoul, Korea. (In Korean)

10

KIBSE (Korean Institute of Bridge and Structural Engineers) (2021) Concrete Bridge Design (Limit State Design Method) (KDS 24 14 21) Design Code and Commentary. Seoul, Korea: KIBSE. (In Korean)

11

Pyo, S. R., Lee, S. W., Lee, E. H., and Lee, J. H. (2023) Evaluation of Fracture Elongation of Steel Reinforcement and Proposal for Gage Length Standard, Journal of Structure Research and Practice, Korean Institute of Bridge and Structural Engineers 1(1), 23-31. (In Korean)

Information
  • Publisher :Korean Institute of Bridge and Structural Engineers
  • Publisher(Ko) :한국교량및구조공학회
  • Journal Title :Journal of Structure Research and Practice
  • Journal Title(Ko) :한국교량및구조공학회 논문집
  • Volume : 2
  • No :2
  • Pages :109-119
  • Received Date : 2024-09-12
  • Revised Date : 2024-12-22
  • Accepted Date : 2024-12-22
  • DOI :https://doi.org/10.22725/JSRP.2024.2.2.109
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