• 콘크리트학회논문집
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• 제15권6호
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• pp.902-912
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• 2003

전 세계적으로 콘크리트 구조물의 열화를 발생하는 가장 중요한 원인은 중성화와 염소이온이다. 대체적으로 많은 콘크리트 구조물에서 염소이온과 중성화로 인하여 철근이 부식되며 이에 대한 많은 연구가 이루어지고 있다. 그러나 실구조물의 상황은 염소이온과 중성화가 복합적으로 발생함에도 불구하고 많은 연구들이 각각의 단일열화에 대한 연구가 이루어지고 있으며 복합열화에 대한 연구는 매우 드문 상황이다. 본 연구는 2중 복합 매체에 대한 확산모델을 이용하여 중성화된 콘크리트의 염소이온 프로파일을 예측하고자 하였다. 실험결과에 의하여 중성화 깊이로부터 3∼5 mm영역에 염소이온의 농축현상이 발생하였으며 2중 복합 구조체에 적용할 수 있는 확산 방정식에 중성화된 콘크리트와 비중성화된 콘크리트의 시간의존적인 염소이온 확산 계수를 고려하여 내구수명예측에 반영하였다.

• 한국측량학회지
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• 제32권3호
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• pp.185-190
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• 2014

The purpose of this research is to extract spectral reflectance characteristics of concretes through basic experiment on concrete specimens and site experiment on actual concrete structures using a field portable spectrometer and a VNIR hyperspectral sensor. A spectrometer (GER-3700) and a VNIR hyperspectral camera (AisaEagle VNIR Hyperspectral Camera) were utilized for extracting spectral characteristics of concrete specimens. Concretes normally show similar patterns that have correlation above 80%, while the high-strengthened concretes display very different results from the normal-strength concretes. We also made a certain conclusion in the laboratory experiment on concrete specimens that both the spectrometer and the VNIR camera vary in spectral reflectance depending on concrete strengths.

• Structural Engineering and Mechanics
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• 제65권3호
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• pp.291-302
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• 2018

Rigid body spring method (RBSM) is an effective tool to simulate the cracking process of structures, and has been successfully applied to investigate the behavior of reinforced concrete (RC) members. However, the theoretical researches and engineering applications of this method mainly focus on two-dimensional problems as yet, which greatly limits its applications in actual engineering projects. In this study, a three-dimensional (3-D) RBSM for RC structures is proposed. In the proposed model, concrete, reinforcing steels, and their interfaces are represented as discrete entities. Concrete is partitioned into a collection of rigid blocks and a uniform distribution of normal and tangential springs is defined along their boundaries to reflect its material properties. Reinforcement is modeled as a series of bar elements which can be freely positioned in the structural domain and irrespective of the mesh geometry of concrete. The bond-slip characteristics between reinforcing steel and concrete are also considered by introducing special linkage elements. The applicability and effectiveness of the proposed method is firstly confirmed by an elastic T-shape beam, and then it is applied to analyze the failure processes of a Z-type component under direct shear loading and a RC beam under two-point loading.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 가을 학술발표논문집(II)
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• pp.597-602
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• 1998

The composite systems, consisting of R/C Columns-Steel Beams, are reasonable structures because of their constructional and economical advantages, workability and so on. But, it is difficult to apply the composite systems to actual design due to material dissimilarity and complicate stress flow in the connection. This study aims to propose the hybrid beam-column connection system with structural tee and through experimental research make clear the shear and moment resistance capacity and stress transfer mechanism.

• 한국구조물진단유지관리공학회 논문집
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• 제24권1호
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• pp.133-141
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• 2020

한국시설안전공단에서는 '시설물의 안전관리에 관한 특별법'에 따라 철근콘크리트 구조물의 안전점검 및 정밀안전진단을 실시하도록 제시하고 있다. 그러나 한국시설안전공단 안전점검 및 정밀안전진단 세부지침의 평가방법에서는 평가결과를 등급으로 제시하기 때문에 구조물의 잔존수명을 알 수 없으며 부등침하가 구조물의 잔존수명에 미치는 영향을 반영하지 못한다. 따라서, 이 연구에서는 부등침하의 영향이 반영된 구조물의 잔존수명 평가모델을 제시하고자 하였다. 부등침하와 각 변위의 상관관계를 나타내는 기존의 연구를 바탕으로 부재의 공칭강도에 부등침하의 영향을 반영시키기 위한 식을 제시하였으며, 실제 철근콘크리트 구조물의 현장데이터를 활용하여 부등침하가 구조물의 잔존수명에 미치는 영향을 분석하였다.

• Coupled systems mechanics
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• 제4권2호
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• pp.173-189
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• 2015

In reality, masonry infill modifies the seismic response of reinforced concrete (r.c.) frame structures by increasing the overall rigidity of structure which results in: increasing of total seismic load value, decreasing of deformations and period of vibration, therefore masonry infill frame structures have larger capacity of absorbing and dissipating seismic energy. The aim of the paper is to explore and assess actual influence of masonry infill on seismic response of r.c. frame structures, to determine whether it's justified to disregard masonry infill influence and to determine appropriate way to consider infill influence by design. This was done by modeling different structures, bare frame structures as well as masonry infill frame structures, while varying masonry infill to r.c. frame stiffness ratio and seismic intensity. Further resistance envelope for those models were created and compared. Different structures analysis have shown that the seismic action on infilled r.c. frame structure is almost always twice as much as seismic action on the same structure with bare r.c. frames, regardless of the seismic intensity. Comparing different models resistance envelopes has shown that, in case of lower stiffness r.c. frame structure, masonry infill (both lower and higher stiffness) increased its lateral load capacity, in average, two times, but in case of higher stiffness r.c. frame structures, influence of masonry infill on lateral load capacity is insignificant. After all, it is to conclude that the optimal structure type depends on its exposure to seismic action and its masonry infill to r.c. frame stiffness ratio.

• 한국건축시공학회지
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• 제6권3호
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• pp.59-66
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• 2006

This study aims to estimate strength approximate to actual concrete strength by presenting appropriate non-destructive strength estimation expression with admixtures such as fly ash, blast furnace slag and silica fume which are used as cement substitute and owing to theirs of cement owing to their equal conditions to blending characteristics of concrete used for domestic structures and their recyclable properties. As a result of comparing error rate of existing expressions and this estimation expression, error rate of this estimation is reduced compared to existing expressions and has higher reliability. When conventional concrete expression is applied to admixture concrete, error rate occurs and then this study suggests the following estimation expressions depending on types of admixture concrete.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계 학술발표회 논문집(II)
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• pp.125-128
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• 2006

As the ministry of construction and transportation established quality standards for recycled aggregate in August, 2005, the consumption of recycled aggregates is expected to be increased in construction fields in the future. Thus the relations between compressive strength of general concretes and that of recycled aggregate concretes which are applied to actual structures are attempted to investigate through non-destruction testing method. Presently Schmitt-Hammer test method is that concrete compressive strength is predicted by measuring surface hardness of concretes, and is well known as the most convenient and simply operated method among many non-destruction testing methods. In this study, cylinder specimen and mock-up were constructed using recycled aggregate concretes made by the first class recycled coarse aggregates and recycled fine aggregates specified in KS F 2573 (recycled aggregate for concrete), and compressive strength of hardened concrete of middle ages was evaluated.

• Structural Engineering and Mechanics
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• 제72권6호
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• pp.737-746
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• 2019

Concrete mechanical properties change constantly with age, temperature, humidity and the other environmental factors. This research studies the effects of temperature and age on the development of concrete elastic modulus by a series of prism specimens. Elastic modulus test was conducted at various temperatures and ages in the laboratory to examine the effects of temperature and age on it. The experimental results reveal that the concrete elastic modulus decreases with the rise of temperature but increases with age. Then, a temperature coefficient K is proposed to describe the effects of temperature and validated by existing studies. Finally, on the basis of K, analytical models are proposed to determine the elastic modulus of concrete at a given temperature and age. The proposed models can offer designers an approach to obtain more accurate properties of concrete structures through the elastic modulus modification based on actual age and temperature, rather than using a value merely based on laboratory testing.

• Advances in concrete construction
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• 제5권1호
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• pp.49-63
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• 2017

Traditional reinforced concrete slabs and beams are widely used for building. The use of flat slab structures gives advantages over traditional reinforced concrete building in terms of design flexibility, easier formwork and use of space and shorter building time. Deflection of the slab plays a critical role on the design and service life of building components; however, there is no recent research to explore actual deformation of concrete slab despite various advancements within the design codes and construction technology. This experimental study adopts the Hydrostatic Levelling Cells method for monitoring the deformation of a multi-storey building with flat slabs. In addition, this research presents and discusses the experimental results for the vertical deformation.