• International Journal of Safety
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• v.8 no.1
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• pp.1-5
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• 2009

The CFRP composite has unique properties that offer high strength and stiffness, even though it has light weight. Therefore it can be used in many industrial applications. When mechanical fasteners are used for joining composites, high stress concentrations appear near the edge of holes prepared for accommodating structural bolts and rivets. This presence of high stress concentrations can be a source of damage. The aim of this work is to evaluate fracture behavior and patterns of plain woven CFRP with circular hole and repairing patch element. The maximum strength and pattern for the plain woven carbon composite specimen with the repaired circular hole were examined. From the results, we show that repairing of the CFRP composite specimen with ($\pi$) 3~5 mm of circular hole diameter results in load rising effect and the repairing is more effective as bigger hole specimen.

• Computers and Concrete
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• v.33 no.4
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• pp.361-372
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• 2024

Reinforced concrete (RC) bridge columns are typically designated as the primary source of energy dissipation for a bridge structure during an earthquake. Therefore, seismic repair of RC bridge columns has been studied extensively during the past several decades. On the other hand, few studies have been conducted to evaluate how repaired column members influence the system-level response of an RC bridge structure in subsequent earthquakes. In this study, a numerical model was established to simulate the response of two large-scale RC columns, repaired using different techniques, reported in the literature. The columns were implemented into a prototype bridge model that was subjected to earthquake loading. Incremental dynamic analysis (IDA) and fragility analysis were conducted on numerical bridge models to evaluate the efficacy of the repairs and the post-repair seismic performance of the prototype bridge that included one or more repaired columns in various locations. For the prototype bridge herein modeled, the results showed that a confinement-enhanced oriented repair would not affect the seismic behavior of the prototype bridge. Increasing the strength of the longitudinal reinforcement could effectively reduce the drift of the prototype bridge in subsequent earthquakes. A full repair configuration for the columns was the most effective method for enhancing the seismic performance of the prototype bridge. To obtain a positive effect on seismic performance, a minimum of two repaired columns was required.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.85-88
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• 2008

Performance evaluation of RC bridge piers repaired by CFRP has been investigated. For this purpose, simplified CFRP stress-strain relationship has been proposed and use is made of inelastic time-dependent element developed by authors. Static time-history analysis has been carried out for a RC bridge pier repaired with CFRP. Analytical predictions shows a relatively good correlation with experimental results. In addition, in case of dynamic time-history analysis, effect of the CFRP repair intervention on shear has been evaluated. Comparative analysis reveals that a repaired member produces increased characteristics due to the repair intervention and may affect the overall response of a whole structure. Moreover, effect of shear significantly affect strength, stiffness and displacement response of the pier. In all, It is believed that the present analytical model and scheme enable a healthy evaluation of strength, stiffness and displacement capacities of a RC bridge pier being damaged and repaired.

• Steel and Composite Structures
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• v.25 no.2
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• pp.231-244
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• 2017

This paper presents the structural identification of an arch dam model for the damaged, repaired and strengthened conditions under different water levels. For this aim, an arch dam-reservoir-foundation model has been constructed. Ambient vibration tests have been performed on the damaged, repaired and strengthened dam models for the empty reservoir (0 cm), 10 cm, 20 cm, 30 cm, 40 cm, 50 cm and full reservoir (60 cm) water levels to illustrate the effects of water levels on the dynamics characteristics. Enhanced Frequency Domain Decomposition Method in the frequency domain has been used to extract the dynamic characteristics. The dynamic characteristics obtained from the damaged, repaired and strengthened dam models show that the natural frequencies and damping ratios are considerably affected from the varying water level. The maximum differences between the frequencies for the empty and full reservoir are obtained as 16%, 33%, and 25% for damaged, repaired and strengthened model respectively. Mode shapes obtained from the all models are not affected by the increasing water level. Also, after the repairing and strengthening implementations, the natural frequencies of the arch dam model increase significantly. After strengthening, between 46-92% and 43-62% recovery in the frequencies are calculated for empty and full reservoir respectively. Apparently, after strengthening implementation, the mode shapes obtained are more acceptable and distinctive compared to those for the damaged model.

• Journal of Environmental Science International
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• v.11 no.11
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• pp.1183-1187
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• 2002

Existing retaining walls are usually made from only one cast form and any damage must be promptly repaired. However, when a part of a retaining wall is repaired, a gap can be created between the repaired and existing parts, along with an unpleasing visual effect. As such, the whole structure is often reconstructed, rather than repairing one part, resulting in construction waste and possible contamination of the environment. Accordingly, the current study proposes a construction method for a retaining wall that uses separate blocks to downsize of quantity of construction waste. In addition, by changing the color or modifying the block cover a more environmentally friendly retaining wall construction method is achieved.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.527-528
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• 2009

Effects of temperature on fatigue resistance of crack zone in concrete members repaired by injecting epoxy resin was experimentally studied. First, a fatigue machine that produces small movement similar to those observed in actual cracks was developed. It was made clear that the rise of temperature changes a mode of fracture at the repaired zone and sharply dropped fatigue resistance.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.217-218
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• 2010

This study presented the analytical evaluation model effective in the concrete structure repaired with a patching material. The model considered the effect of the repair material on carbon dioxide penetration into the repaired concrete as evaluating the remaining service life of the CO2-deteriorated concrete structure after repair. The diffusion profiles of carbon dioxide as well as the carbonated concrete were effectively able to be modelled with analytical method based on Fick's 1st diffusion law.

• Toxicological Research
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• v.11 no.2
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• pp.229-234
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• 1995

This study was carried out to evaluate the cytotoxicity of cadmium on 3T3 fibroblast and to develop the antidote on 3T3 fibroblast which was injuried by $IC_{50}$ of cadmium. The groups for repaired effects were divided into 7 groups such as medium alone treated group. Cadmium treated $IC_{50}$ groups and 5 experimental groups $(IC_{50}$ cadmium plus $10^{-4}$ concentration of each methanol fraction). After incubation for 48 hrs in the same conditions, MTT (tetrazolium MTT), NR (neutral red) and SRB (sulforhodamine B protein) assay were measured. Light microscopic observations were also investigated. The ethyl acetate fraction of Perilla frutescens showed significantly repaired effect against cadmium cytotoxiclty and this fraction inhibited critical cell regeneration in light microscopy.

• Journal of Information Processing Systems
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• v.16 no.5
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• pp.1129-1144
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• 2020

The thangka image inpainting method based on wavelet transform is not ideal for contour curves when the high frequency information is repaired. In order to solve the problem, a new image inpainting algorithm is proposed based on edge structural constraints and wavelet transform coefficients. Firstly, a damaged thangka image is decomposed into low frequency subgraphs and high frequency subgraphs with different resolutions using wavelet transform. Then, the improved fast marching method is used to repair the low frequency subgraphs which represent structural information of the image. At the same time, for the high frequency subgraphs which represent textural information of the image, the extracted and repaired edge contour information is used to constrain structure inpainting in the proposed algorithm. Finally, the texture part is repaired using texture synthesis based on the wavelet coefficient characteristic of each subgraph. In this paper, the improved method is compared with the existing three methods. It is found that the improved method is superior to them in inpainting accuracy, especially in the case of contour curve. The experimental results show that the hierarchical method combined with structural constraints has a good effect on the edge damage of thangka images.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.04a
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• pp.138-145
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• 2001

This paper presents F.E.M. analysis result about the behavior of R.C. beam repaired with steel plate and fiber sheet. The effect of repairing varies with reinforcement ratio of R.C. beam, plate thickness, numbers of fiber sheet, and repairing length, etc. F.E.M. analysis using a program, DIANA, was carried out taking these factors as parameter in this study. Analysis result shows that repaired R.C. beam behaves differently according to parameters and certain cases imply that repairing is useless or may lay structure in dangerous condition. F.E.M. model considers that interfacial behavior between different two parts of repaired beam is rigid based on an assumption that adhesive failure does not appear before yielding of reinforcement and its analysis shows the result coincides with that of experiment.