高品質 循環骨材를 使用한 鐵筋콘크리트 보의 長ㆍ短期 構造性能

다국어 초록 (Multilingual Abstract)

The construction wastes are increasing due to the increased re-construction and re-development activities along with the continuous growth of domestic construction industry, and this trend will accelerate with various social demands and the desire for improved quality of life. According to a report of the Ministry of Environment of the Republic of Korea, about 100 thousand tons of construction wastes are produced on the daily average and create a serious environmental hazard. Thus, the Republic of Korea recognized the problems of environmental pollution and shortage of aggregate supply and recently stipulated <Proposal for the Legalization of the Promotion for the Recycling of Construction Waste> to mandate the use of recycled aggregate in construction of a specified size. Additionally, the ministry is preparing various policies to promote the use of recycled aggregate in such efforts as easing on the restriction of the volumetric ratio and height of an architectural structure up to 15% by the weight ratio of the construction waste usage to the total quantity of aggregate used in the frame construction of the architecture. However, it is required based on a research to establish a governmental policy on the promotion of the recycled aggregate and to secure the reliability of the short-term and long-term structural performance of recycled aggregate and the steel concrete structural member with recycled aggregate, first of all, in order for the recycled aggregate to be widely used for various structural members in the construction field.
Accordingly, this study prepares recycled coarse aggregate and recycled fine aggregate having the quality performance equivalent to natural aggregate for the active use of the concrete with recycled aggregate and evaluates the dynamic performance of the concrete with recycled aggregate so that the quality and reliability of the concrete with recycled aggregate can be established. Additionally, (1) the short-term behavior of the steel concrete member with recycled aggregate such as bending, shear, bonding, and splicing (or coupling) and (2) the long-term behavior due to long-term loading and fatigue loading are analyzed based on this research. This study aims to examine the structural performance of the recycled-aggregate concrete in the actual architecture by comparing the experimental result with the theoretical result from the existing research, standard equations, and prediction equations for the strength and deflection.
This research employed three mixtures of concrete - natural coarse aggregate + natural fine aggregate, recycled coarse aggregate (100%) + natural fine aggregate, natural coarse aggregate + natural fine aggregate (50%) + recycled fine aggregate (50%). A total of thirteen test specimens including four specimens for bending test, three specimens for bonding-splicing test, and six specimens for shear test were prepared for the examination of their short-term structural performance. Additionally, three specimens for bending test and three specimens for fatigue test were prepared for long-term structural performance test.
The result of experiment on short-term structural behavior revealed that all test specimens of the steel concrete beam reinforced for shear manifested equivalent performance in crack strength, shear strength, and shear bearing capacity. Moreover, they exhibited higher strength than the shear capacity as specified by the ACI code and values of fundamental research. Additionally, as the replacement ratio of the recycled coarse aggregate increases, all test specimens exhibited lower experimental values compared to the calculated, predicted values. The RH30-0.75 specimen of flexural yield-type of steel concrete beam, which replaced 50% of the fine aggregate with recycled fine aggregate, exhibited the diagonal tensile crack propagating deeper into the flexural compressive side and a rapid decline in the strength after reaching the maximum bearing capacity. Additionally, when the experimental values were compared with the predicted values from the equation of ACI code on bending strength, they exhibited 18.5~23.6% higher in bending strength and 23.5~26.3% higher in bonding-slicing strength than the computed values. Thus, the result of examining the short-term structural performance of shear and flexural behavior revealed that the possibility of applying recycled aggregate to a structural member was deemed to be very feasible.
The result of a long-term structural behavior test revealed that the CEB-FIP equation for the prediction of long-term deflection such as the creep coefficient and dry shrinkage was more accurate in the prediction of the long-term deflection than the predicted values from ACI 209 equation. Moreover, the equation of ACI 318 code over-estimated the long-term deflection. Meanwhile, Branson, EMM, and AEMM predicted the long-term deflection very well. Especially, AEMM predicted the long-term deflection of the recycled aggregate concrete beam within 1% error so that these prediction equations were also very useful in the rational consideration for the long-term behavior of recycled aggregate concrete structures.
When the steel concrete beam with recycled aggregate, which was damaged due to long-term loading, was tested for short-term bending behavior, the experimental values were in the safe side in comparison with the values computed from the ACI standard equation. Thus, it is construed that the applicability of current standard equations are very high in designing of the bending strength for the recycled aggregate concrete beam within the scope of this research. The result of the experiment on fatigue behavior showed that the steel concrete beam with recycled aggregate exhibited a great deal of deflection and various deformations during the initial fatigue loading test than the test specimen with natural aggregate. Moreover, all specimens resulted in a total failure due to the fracture of the steel bar from the repetitive fatigue loading. Thus, it is deemed that additional research on these initial stiffness characteristics, which influence the durability of the concrete structural member with recycled aggregate, is required.
Additionally, it was found that the prediction equation on deflection due to fatigue loading as proposed by Balaguru and Shah considered the concrete strength only among the elements of flexural strength reduction and repetitive creep of concrete and did not predict accurately the amount of deflection of the concrete with recycled aggregate due to fatigue loading. Thus, an extensive research on the fatigue behavior characteristics of the recycled aggregate concrete under repetitive stress and the bonding capacity of the concrete member and rebar member of a concrete beam with recycled aggregate during fatigue loading should be conducted.
The result of evaluating the dynamic characteristics of the concrete with recycled aggregate and the experimental analyses of the short-term and long-term structural performance of steel concrete beam with recycled aggregate revealed that their behaviors were very similar to the behavior of concrete with natural aggregate as a whole. Accordingly, it is deemed that the application of recycled aggregate of good quality to a steel concrete member is possible within the scope of this research, which satisfied existing specifications on the concrete standard. Nonetheless, it is also deemed that future research, which considers various environmental factors such as freezing-thaw and salt damage during the time period of durability, and the re-establishment of the standards on the performance of the concrete with recycled aggregate should be carried out in order to apply these recycled aggregate widely to actual construction structures.

목차 (Table of Contents)

• 제1장 서론 1
• 1.1 연구의 배경 및 필요성 1
• 1.2 순환골재 콘크리트 및 이를 사용한 철근콘크리트 부재의 구조성능에 관한 기존연구 분석 8
• 1.2.1 순환골재 콘크리트의 역학적 특성 및 부착특성에 관한 연구 8
• 1.2.2 순환골재 철근콘크리트 보의 단기 구조성능 평가에 관한 연구 11
• 1.2.3 순환골재 철근콘크리트 보의 장기 구조성능 평가에 관한 연구 11
• 1.3 연구의 목적 13
• 1.4 연구의 범위 및 방법 15
• 1.4.1 순환골재 콘크리트의 역학적 특성 평가 15
• 1.4.2 순환골재 콘크리트를 적용한 철근콘크리트 부재의 단기 구조성능 평가 15
• 1.4.3 순환골재 콘크리트를 적용한 철근콘크리트 부재의 장기 구조성능 평가 16
• 1.5 논문의 구성 18
• 제2장 순환골재 콘크리트의 역학적 특성 평가 20
• 2.1 서언 20
• 2.2 순환골재 콘크리트의 역학적 특성에 관한 실험 22
• 2.2.1 실험계획 22
• 2.2.2 사용재료 22
• 2.2.3 콘크리트 배합 28
• 2.2.4 비빔방법 및 시험체 제작 28
• 2.2.5 실험방법 32
• 2.2.5.1 압축강도 및 탄성계수 32
• 2.2.5.2 할렬인장강도 33
• 2.3 골재 종류에 따른 콘크리트의 역학적 특성 35
• 2.3.1 압축강도 35
• 2.3.2 할렬인장강도 38
• 2.3.3 탄성계수 38
• 2.4 소결 41
• 제3장 순환골재 철근콘크리트 보의 전단성능 42
• 3.1 서언 42
• 3.2 철근콘크리트 보의 전단강도 규준식 및 예측식 44
• 3.2.1 ACI 규준 44
• 3.2.2 Zsutty 제안식 44
• 3.2.3 AIJ 지침 45
• 3.3 시험체 계획 및 제작 46
• 3.4 실험방법 51
• 3.5 실험결과 및 분석 53
• 3.5.1 균열 및 파괴 상황 53
• 3.5.2 하중-처짐 관계곡선 61
• 3.5.3 보유전단내력 63
• 3.5.4 규준식과의 비교 65
• 3.5.5 현행 규준식 및 제안식과의 비교 66
• 3.5.6 철근변형률 69
• 3.5.7 콘크리트 변형률 72
• 3.6 소결 74
• 제4장 순환골재 철근콘크리트 보의 휨 및 이음성능 76
• 4.1 서언 76
• 4.2 철근콘크리트 보의 휨강도에 관한 ACI 규준 78
• 4.3 시험체 계획 및 제작 80
• 4.4 실험방법 84
• 4.5 실험결과 및 분석 85
• 4.5.1 균열 및 파괴양상 85
• 4.5.2 하중-처짐 관계 90
• 4.5.3 ACI 규준식과의 비교 95
• 4.5.4 모멘트-곡률 관계 97
• 4.5.5 하중-평균 균열폭 관계 99
• 4.5.6 철근 및 콘크리트 변형률 101
• 4.5.7 중립축 변화 105
• 4.6 소결 106
• 제5장 순환골재 철근콘크리트 보의 장기 휨거동 특성 108
• 5.1 서언 108
• 5.2장기처짐 예측에 관한 규준 및 제안식 110
• 5.2.1 크리프 및 건조수축 110
• 5.2.2 크리프 및 건조수축 예측식 110
• 5.2.2.1 CEB-FIP 규준 111
• 5.2.2.2 ACI 규준 112
• 5.2.3 기존 장기처짐 예측 방법 및 제안식 115
• 5.2.3.1 ACI 규준 115
• 5.2.3.2 Branson 방법 116
• 5.2.3.3 Mayer 방법 117
• 5.2.3.4 Neville 방법 117
• 5.2.3.5 EMM 방법 117
• 5.2.3.6 AEMM 방법 118
• 5.3 시험체 계획 및 제작 120
• 5.4 실험방법 121
• 5.5 실험결과 및 분석 123
• 5.5.1 장기 휨성능 평가 123
• 5.5.1.1 균열양상 123
• 5.5.1.2 시간에 따른 보의 처짐특성 124
• 5.5.1.3 기존 장기거동 예측식에 의한 결과 및 본 연구에서의 수정제안식 평가 126
• 5.5.2 지속하중 제하시 거동 136
• 5.5.2.1 처짐 회복 특성 136
• 5.5.2.2 변형률 회복 특성 136
• 5.5.2.3 초기값에 대한 회복량 비교 136
• 5.5.3 지속하중을 경험한 보의 휨거동 139
• 5.5.3.1 균열 및 파괴양상 139
• 5.5.3.2 모멘트-처짐 관계 142
• 5.5.3.3 철근 및 콘크리트 변형률 146
• 5.5.3.4 모멘트-곡률 관계 151
• 5.3.3.5 모멘트-평균균열폭 관계 152
• 5.3.3.6 중립축 변화 153
• 5.6 소결 154
• 제6장 순환골재 철근콘크리트 보의 피로성능 156
• 6.1 서언 156
• 6.2 피로하중을 받는 철근콘크리트 부재에 관한 규준 및 제안식 158
• 6.2.1 ACI 규준 158
• 6.2.2 Balaguru 및 Shah 제안식 158
• 6.3 시험체 계획 및 제작 161
• 6.4 실험방법 163
• 6.5 실험결과 및 분석 165
• 6.5.1 균열 및 파괴양상 165
• 6.5.2 피로하중-처짐 관계 167
• 6.5.3 강성저하특성 171
• 6.5.4 철근 변형률 172
• 6.6 실험값과 계산값과의 비교 173
• 6.7 소결 176
• 제7장 종합결론 177
• 7.1 순환골재 콘크리트의 역학적 특성 177
• 7.2 순환골재 철근콘크리트 보의 단기 구조성능 178
• 7.3 순환골재 철근콘크리트 보의 장기 구조성능 179
• 참고문헌 180
• ABSTRACT 191