• Computers and Concrete
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• 제20권5호
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• pp.511-519
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• 2017

The reliability of reinforced concrete structures is frequently compromised by the deterioration caused by reinforcement corrosion. Evaluating the effect caused by reinforcement corrosion on structural behaviour of corrosion damaged concrete structures is essential for effective and reliable infrastructure management. In lifecycle management of corrosion affected reinforced concrete structures, it is difficult to correctly assess the lifecycle performance due to the uncertainties associated with structural resistance deterioration. This paper presents a stochastic deterioration modelling approach to evaluate the performance deterioration of corroded concrete structures during their service life. The flexural strength deterioration is analytically predicted on the basis of bond strength evolution caused by reinforcement corrosion, which is examined by the experimental and field data available. An assessment criterion is defined to evaluate the flexural strength deterioration for the time-dependent reliability analysis. The results from the worked examples show that the proposed approach is capable of evaluating the structural reliability of corrosion damaged concrete structures.

• Earthquakes and Structures
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• 제16권2호
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• pp.235-251
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• 2019

Corrosion of reinforcement is the greatest threat to the safety of existing reinforced concrete (RC) structures. Most of the olden structures are gravity load designed (GLD) and are seismically deficient. In present study, investigations are carried out on corrosion damaged GLD beam-column sub-assemblages under reverse cyclic loading, in order to evaluate their seismic performance. Five GLD beam-column sub-assemblage specimens comprising of i) One uncorroded ii) Two corroded iii) One uncorroded strengthened with steel bracket and haunch iv) One corroded strengthened with steel bracket and haunch, are tested under reverse cyclic loading. The performances of these specimens are assessed in terms of hysteretic behaviour, energy dissipation and strength degradation. It is noted that the nature of corrosion i.e. uniform or pitting corrosion and its location have significant influence on the behaviour of corrosion damaged GLD beam-column sub-assemblages. The corroded specimens with localised corrosion pits showed in-cyclic strength degradation. The study also reveals that external strengthening which provides an alternate force path but depends on the strength of the existing reinforcement bars, is able to mitigate the seismic risk of corroded GLD beam-column sub-assemblages to the level of control uncorroded GLD specimen.

• 한국건설순환자원학회논문집
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• 제9권2호
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• pp.143-151
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• 2021

이 논문에서는 철근 부식을 촉진시킨 휨 부재의 4점 재하 재하실험을 통하여 철근 지름 및 부식률의 변화에 따른 처짐과 곡률 및 균열모멘트의 변화를 측정하는 실험을 수행하였다. 부식률은 중량비로 0%, 2%, 5% 및 10%로 변화하였으며, 철근의 지름은 각각 10mm, 13mm 및 19mm로 하였다. 실험 결과에 따르면 처짐에 대한 철근 지름의 영향은 크지 않았으며, 철근의 부식률이 2%를 초과하는 경우 부식되지 않은 철근을 가진 부재에 비하여 처짐이 증가하고 균열모멘트가 감소하는 경향을 확인하였다. 이는 부식된 철근에 대한 직접인발 시험과 동일한 경향을 보이는 것이며, 철근의 부식률이 크지 않은 경우 휨거동에 대한 부식의 영향이 크지 않음을 의미한다. 또한, 철근이 부식된 철근콘크리트 부재의 처짐량을 산정하기 위하여 부식률에 따른 균열모멘트의 변화를 반영하는 처짐 보정계수를 도출하고 실험결과를 통하여 그 적용성을 확인하였다.

• 한국산학기술학회논문지
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• 제16권10호
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• pp.6551-6557
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• 2015

철근부식에 의해 발생된 녹은 철근 주변의 콘크리트에 팽창 압력을 유발하여 콘크리트의 균열, 피복콘크리트의 박리나 탈락, 철근의 단면적 감소 등 구조물의 내구성에 부정적인 영향을 끼친다. 본 논문에서는 코일철근을 대상으로 3차원 스캐너를 이용하여 철근이 부식됨에 따른 표면적을 측정하여 철근의 부식률과 표면 거칠기와의 관계를 프랙탈 이론을 이용하여 규명하였다. 코일 철근은 현장 적재일이 길수록 부식률이 증가하였으며, 부식률이 증가할수록 표면 거칠기는 거칠게 평가되었다. 프랙탈 차원의 증가량은 적재일 3일, 7일, 14일, 21일 경우 각각 0.0235, 0.0280, 0.0319, 그리고 0.0455로 나타났다. 이때의 부식률은 각각 0.3367%, 0.6127%, 0.7898%, 그리고 1.1965%로 나타나 프랙탈 차원을 이용한 부식된 코일철근의 표면 물리량 평가는 실제 부식률과 유사한 결과를 나타냈다.

• Structural Engineering and Mechanics
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• 제27권3호
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• pp.347-363
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• 2007

Assessment of structural behaviour of corrosion affected structures is an important issue, which would help in making certain decisions pertaining to the inspection, repair, strengthening, replacement and demolition of such structures. The paper presents formulations to predict the loss of weight and the loss of cross-sectional area of the reinforcing bar undergoing corrosion based on the earlier study carried out by the present authors (Bhargava et al. 2006). These formulations have further been used to analytically evaluate the ultimate bending moment and ultimate shear force capacity of the corroded concrete beams. Results of the present study indicate that, a considerably good agreement has been observed between the experimental and the analytically predicted values for the weight loss and reduction in radius of the corroded reinforcing bars. A considerably good agreement has also been observed between the experimental and the analytically predicted values of ultimate bending moment and ultimate shear force capacity for the corroded concrete beams.

• Computers and Concrete
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• 제15권3호
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• pp.411-436
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• 2015

In this work, a comprehensive approach to model the structural behaviour of Reinforced Concrete (RC) beams subjected to reinforcement corrosion is proposed. The coupled environmental - mechanical damage model developed by some of the authors is enhanced for considering the main effects of corrosion on concrete, on composite interaction between reinforcement bars and concrete and on steel reinforcement. This approach is adopted for reproducing a set of experimental tests on RC beams with different corrosion degrees. After the simulation of the sound beams, the main parameters involved in the relationships characterizing the effects of corrosion are calibrated and tested, referring to one degraded beam. Then, in order to validate the proposed approach and to assess its ability to predict the structural response of deteriorated elements, several corroded beams are analyzed. The numerical results show a good agreement with the experimental ones: in particular, the proposed model properly predicts the structural response in terms of both failure mode and load-deflection curves, with increasing corrosion level.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회논문집(I)
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• pp.718-723
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• 2000

Corrosion is a world wide problem effecting a large number of structure. Cost of repair and rehabilitation on reinforcement structure damaged by steel corrosion is expensive. But structural capacity on low level corrosion is increased. So this experimental study was performed to know structural performance on reinforced concrete slabs with low level corroded bars. As in the case of test samples, bond stress and structural capacity increases up to 2% corrosion level.

• Earthquakes and Structures
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• 제26권4호
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• pp.269-283
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• 2024

When a reinforced concrete (RC) structure is exposed to a corrosive environment for an extended period of time, the material qualities deteriorate, resulting in a loss in seismic performance. Engineered Cementitious Composites (ECC) have been used to reinforce the corroded RC structure, which can achieve reinforcement effectiveness for a small change in cross-section size. In this work, finite element models of unjacketed RC pier and ECC jacketed pier were established and verified by experimental tests, with the buckling effect of longitudinal reinforcement considered. Compared with the unjacketed pier, the displacement of the pier top of the ECC jacketed pier was reduced by about 9.52% under earthquake action. In the case of moderate and major earthquakes, the probability of exceedance of ECC jacketed pier is significantly reduced. For the case of rare earthquake loading, with the ECC jacket, the e of the pier experiencing serious damage and complete damage states is reduced by 10.29% and 29.78%, respectively.

• Structural Engineering and Mechanics
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• 제47권6호
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• pp.773-790
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• 2013

Bending behaviors of corroded reinforced concrete (RC) beams under repeated loading were investigated experimentally. A total of twenty test specimens, including four non-corrosion and sixteen corrosion reinforced concrete beams, were prepared and tested. A numerical model for flexural and cracking behaviors of the beam under repeated loading was also developed. Effects of steel corrosion on reinforced concrete beams regarding cracking, mid-span deflection, stiffness and bearing capacity of corroded beams were studied. The impact of corrosion on bond strength as the key factor was investigated to develop the computational model of flexural capacity. It was shown from the experimental results that the bond strength between reinforcement and concrete had increased for specimen of low corrosion levels, while this effect was changed when the corrosion level was higher. It was indicated that the bearing capacity of corrosion beam increased even at a corrosion level of about 5%.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 가을 학술발표회 논문집
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• pp.281-286
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• 1997

Recent construction activities and maintenance of marine facilities have been accelerating to keep up with rapid economic growth in Korea. Marine concrete structures are exposed to salts an chloride from ocean environments. The corrosion of reinforcement steel caused by chloride-penetration into concrete may severely effect the durability of concrete structures. The objective of this research is to develop a durable concrete by investigating the corrosion resistance of various corrosion protection systems utilizing different water/cement ratio, silica fumes, corrosion inhibitors and etc. A tow-year verification test on various corrosion protection systems has been doing in the laboratory and at the seaside. Corrosion investigations on reinforcement steel are now under progress for more than 180 concrete specimen. Corrosion-related measurements include macrocell corrosion current, instant-off voltage between corroding and noncorroding reinforcement, chloride contents, the corroded surface areas on the reinforcement steel, and etc. A low level of corrosion is investigated on reinforcement steels in concrete specimen made with corrosion inhibitors or applied aqueous impregnating corrosion inhibitors into their surface, even though high chloride contents of concrete specimen.