• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
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• pp.394-397
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• 2006

For checking fatigue safety and endurance of precast concrete deck and loop joint system in the steel plate girder composite bridge, the test composite bridge model was made for the fatigue experiment by the wheel load machine. The fatigue tests of 1,000,000 cycles were implemented according to wheel load condition of DB24 rear axle of Korea Highway Design Code. From the test results, the loop joint system for the precast deck has a sufficient flexural capacity. Although a little lower longitudinal continuity capacity is evaluated than general sound cast-in-place RC bridge deck, there is no problem about the safety. The overall fatigue level of safety defined by the code is satisfied.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2009년도 춘계 학술대회 제21권1호
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• pp.249-250
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• 2009

최근 고강도의 프리캐스트 부재 사용이 증가하고 프리캐스트 부재 품질에 대한 수요자의 요구가 높아짐에 따라 별도의 다짐 작업이 필요 없는 자기충전 콘크리트에 대한 관심이 증가하고 있다. 본 연구에서는 설계강도 60MPa 고강도 자기충전 콘크리트를 이용하여 7m 길이의 프리캐스트 보 부재를 제작하였으며, 그 결과 시공성, 강도, 품질 측면에서 양호한 결과를 얻었다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 춘계 학술발표회 제20권1호
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• pp.341-344
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• 2008

본 논문은 프리텐션 프리스트레스트 구조물의 긴장재 용접 절단에 따른 콘크리트의 응력을 실험적으로 고찰하였다. 14개의 긴장재를 1열 배치한 3개의 슬래브 실험체를 제작하여 실험을 수행하였다. 긴장력 도입 중 종방향 및 횡방향 철근에 배치된 변형률 게이지로부터 변형률의 변화를 측정하였다. 실험 결과, 횡방향 변형률이 긴장재의 절단 순서에 따라 변화되는 것을 확인할 수 있었다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 봄 학술발표회 논문집(I)
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• pp.259-264
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• 1999

The aim of this study of to compare the development of compressive strength of high-strength concrete with maturity and investigate the applicability the strength prediction models. An experiment was attempted on the high-strength concrete mixes using portland cement replaced by silica fume of 10% by weight of cement, the water-binder ratios of mixes being 0.30 and 0.35, the curing temperatures being 30, 20, 10, 5$^{\circ}C$. Test results of mixes are statistically analyzed to infer the correlation coefficient between the maturity and the compressive strength of high-strength concrete. The constant of strength prediction equation were determined from test results, and the equation was adopted to predict the strength of slab(W80$\times$D100$\times$H20cm). The slab was cast in the laboratory from the same batch water-binder ratio of 0.30, and cores were cut from slab in order to estimate the actual strength. These values are used to compare with predicted value. The present study allows more realistic determination of early age compressive strength of high-strength concrete and can be efficiently used to control the quality in actual construction.

• KCI Concrete Journal
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• 제13권1호
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• pp.61-67
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• 2001

For the design of shear connection for the composite precast concrete slabs. it is necessary to investigate its strength, stiffness, slip capacity and fatigue endurance. For theme purposes, push-out tests were performed with variations of the stud shank diameter and the compressive strength of the mortar. From the experimental studies, it could be observed that the deformation of the shear studs in a full-depth precast concrete slabs were greater than those in a cast-in-place slabs. The static strength of the shear connections obtained agree approximately with those evaluated from the tensile strength of the stud shear connectors owing to the effect of the bedding layer between the slabs and the beams. An empirical equation for the initial shear stiffness of a shear connection was also proposed. On the basis of the push-out tests, a full-scale composite beams with 8.0m span was designed and fatigue tests were carried out to study the behaviour of the stud shear connection and its effects on the flexural behaviour of the beam. The bonding arid friction between the concrete slab and the steel beam considerably increased the fatigue endurance of the shear connection.

• Steel and Composite Structures
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• 제25권2호
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• pp.245-255
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• 2017

The performance of an Industrialised Building System (IBS) consists of prefabricated reinforced concrete components, is greatly affected by the behaviour of the connection between beam and columns. The structural characteristics parameters of a beam-to-column connection like rotational stiffness, strength and ductility can be explained by load-rotation relationship of a full scale H-subframe under gravitational load. Furthermore, the connection's degree of rigidity directly influences the behaviour of the whole frame. In this research, rotational behaviour of a patented innovative beam-to-column connection with unique benefits like easy installation, no wet work, no welding work at assembly site, using a hybrid behaviour of steel and concrete, easy replacement ability, and compatibility with architecture was investigated. The proposed IBS beam-to-column connection includes precast concrete components with embedded steel end connectors. Two full-scale H-subframes constructed with a new IBS and conventional cast in-situ reinforced concrete system beam-to-column connections were tested under incremental static loading. In this paper, load-rotation relationship and ratio of the rigidity of IBS beam-to-column connection are studied and compared with conventional monolithic reinforced concrete connection. It is concluded that this new IBS beam-to-column connection benefits from more rotational ductility than the conventional reinforced concrete connection. Furthermore, the semi-rigid IBS connection rigidity ratio is about 44% of a full rigid connection.

• International Journal of Concrete Structures and Materials
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• 제5권2호
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• pp.119-123
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• 2011

Presented in the paper are findings of a project that examined the effect of slag grade and cement source on the performance of concrete mixtures. Slag cement contents were 20, 40, and 60 percent of the total cementitious material content. Two grades of slag cement were examined (Gr. 100 and Gr. 120) along with two sources of Type I cement. Compressive strength, durability, and permeability were measured. The results showed that the cement source affected the early age strength of the mixtures. At 28 days of age, mixtures containing Gr. 120 slag cement had higher compressive strengths than mixtures containing Gr. 100 slag cement, but by 90 days of age, the trend reversed. As for the chloride ion penetrability, mixtures cast with Gr. 100 slag cement passed fewer coulombs at 28 and 90 days of age than similar mixtures containing Gr. 120 slag. Mixtures containing Gr. 120 slag had the greatest durability factors.

• Structural Engineering and Mechanics
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• 제23권5호
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• pp.469-486
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• 2006

The main objective of this study was to investigate the seismic behavior of damaged reinforced concrete frames rehabilitated by introducing cast in place reinforced concrete infills. Four bare and five infilled frames were constructed and tested. Each specimen consisted of two (twin) 1/3-scale, one-bay and two-story reinforced concrete frames. Test specimens were tested under reversed-cyclic lateral loading until considerable damage occurred. RC infills were then introduced to the damaged specimens. One bare specimen was infilled without being subjected to any damage. All infilled frames were then tested under reversed-cyclic lateral loading until failure. While some of the test frames were detailed properly according to the current Turkish seismic code, others were built with the common deficiencies observed in existing residential buildings. The variables investigated were the effects of the damage level and deficiencies in the bare frame on the seismic behavior of the infilled frame. The deficiencies in the frame were; low concrete strength, inadequate confinement at member ends, 90 degree hooks in column and beam ties and inadequate length of lapped splices in column longitudinal bars made above the floor levels. Test results revealed that both the lateral strength and lateral stiffness increased significantly with the introduction of reinforced concrete infills even when the frame had the deficiencies mentioned above. The deficiency which affected the behavior of infilled frames most adversely was the presence of lap splices in column longitudinal reinforcement.

• 한국건축시공학회지
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• 제22권6호
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• pp.631-640
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• 2022

최근 국내외 건설 현장에서 불법 가수 및 품질관리 미흡으로 인한 건설재해가 발생되고 있다. 본 연구에서는 현장타설 구조체 콘크리트의 품질관리 상태 및 시공단계에서의 임의가수량 판정을 위한 기준점으로 활용하기 위해, ASTM C 642에서 제안한 공극률 시험방법을 도입하고자 하였다. 이를 위해 코어링 대상의 모사 구조체 콘크리트를 타설하고, 같은 배합을 가지는 콘크리트 원주형 공시체를 함께 제작하여, 코어링 도중 발생한 공극률의 증가 수준에 대한 기초자료를 확보하고자 하였다. 압축강도 및 탄성계수는 코어링을 진행한 시편에서 낮게 나타났는데, 이는 코어링 도중 발생한 미세균열의 영향으로 판단된다. 공극률 측정 결과 각 시편간의 데이터 편차는 1% 미만으로 매우 정확한 값을 도출하였으며, 원주형 공시체와 코어링된 공시체 사이의 공극률 차이는 최대 1.69%로 확인되었다. 이 값을 보정치로 활용하면, 현장 콘크리트와 원주형 콘크리트 사이의 실공극률 추산이 가능하며, 이의 상호 비교를 통해 현장 구조체 콘크리트의 품질관리 상태 및 임의가수량의 판단이 가능할 것으로 확인되었다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2021년도 봄 학술논문 발표대회
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• pp.185-186
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• 2021

In Korea, many buildings are built with underground spaces and cast-in-place pile method is mostly applied in the temporary retaining walls for the underground space construction. A H-shaped steel section is generally embedded in the soldier pile in the C.I.P method. In this study, a new and economical section with high strength steel replacing the H-shaped section was proposed and its flexural capacity was evaluated experimentally. The new section is the concrete-filled composite section with pentagonal thin plate and thick flange plate. Test results showed that the proposed section has an excellent flexural strength and ductility.