• International Journal of Highway Engineering
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• v.17 no.1
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• pp.83-90
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• 2015

PURPOSES : The purpose of this study is to investigate the relationship between the crack propagation depth through a slab and crack width movement in continuously reinforced concrete slab systems (CRCSs). METHODS : The crack width movements in continuously reinforced concrete pavement (CRCP) and continuously reinforced concrete railway track (CRCT) were measured in the field for different crack spacings. In addition, the crack width movements in both CRCP and CRCT were simulated using finite element models of CRCP and CRCT. The crack width movements, depending on the unit temperature change, were obtained from both the field tests and numerical analysis models. RESULTS : The experimental analysis results show that the magnitudes of the crack width movements in CRCSs were related to not only the crack spacing, but also the crack propagation depth. In CRCP, the magnitudes of the crack width movements were more closely related to the crack propagation depths. In CRCT, the crack width movements were similar for different cracks since most were through cracks. If the numerical analysis was performed to predict the crack width movements by assuming that the crack propagates completely through the slab depth, the predicted crack width movements were similar to the actual ones in CRCT, but those may be overestimated in CRCP. CONCLUSIONS : The magnitudes of the crack width movements in CRCSs were mainly affected by the crack propagation depths through the slabs.

• Structural Engineering and Mechanics
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• v.15 no.2
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• pp.159-180
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• 2003

In this paper spacing and width of flexural cracks in reinforced concrete beams are determined using two-dimensional finite element analysis. At early loading stages on the beam the primary crack spacing is based on the slip length, which is the development length required to resist the steel stress increment that occurs at a cracked section on the formation of the first flexural crack. A semi-empirical formula is presented in this paper for the determination of the slip length for a given beam. At higher load levels, the crack spacing is based on critical crack spacing, which is defined as the particular crack spacing that would produce a concrete tensile stress equal to the flexural strength of concrete. The resulting crack width is calculated as the relative difference in extensions of steel reinforcement and adjacent concrete evaluated at the cracked section. Finally a comparative study is undertaken, which indicates that the spacing and width of cracks calculated by this method agree well with values measured by other investigators.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.105-108
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• 2000

With exact analysis of cracks in RC beam, present or past stress states can be traced. For analysis of Flexural cracks, experiments are carried out focusing on variation of crack widths and crack spacing due to stress, beam properties. The crack width expectation formulas of each code are compared and initial crack spacing expectation formula is proposed.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.1235-1240
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• 2005

In this status no inspection standard of quality in repair of present concrete structure has a problem to repair for simple experience. In this paper for this problem improvement, it made an analysis of relation to injection quantity of crack width, injection time of crack width, injection pressure of crack width, injection pressure and time, injection quantity of structural size, injection quantity of structural individual crack position, injection time about crack width. and structural thickness. The data gained in analysis result be judged that it will help in systematic quality control about concrete structural repair.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.1
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• pp.115-122
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• 2006

Repairing concrete structures depended on only technician' experience without quality test standards would have problems. For solving those problems, this paper has analyzed the relations between injection quantify and crack width, injection time and crack width, injection pressure and crack width, injection pressure/time and crack width, injection quantity and structure size, injection quantify and individual crack Position, injection time and crack width/structure thickness. The data gained from this analysis would be helpful for systematic quality control of repairing concrete structures.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.903-908
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• 2001

This paper deals with the estimation of the maximum flexural crack widths using minimum crack spacing for reinforced concrete members. The proposed method utilizes the conventional crack and bond-slip theories as well as bonding transfer length and effects of creep and shrinkage between the reinforcement and concrete. An analytical equation for the estimation of the maximum flexural crack width is formulated as a function of mean bond stress. The validity, accuracy and efficiency of the proposed method are established by comparing the analytical results with the experimental data and the major code specifications (e.g., ACI, CEB-FIP Model code, Eurocode 2, etc.). The analytical results of analysis presented in this paper indicate that the proposed method can be effectively estimated the maximum flexural crack width of the reinforced concrete members.

• Structural Engineering and Mechanics
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• v.20 no.1
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• pp.1-20
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• 2005

The present paper deals with the seismic response analysis and the evaluation of most likely failure modes for a water storage structure. For the stress analysis, a 3-D mathematical model has been adopted to represent the structure appropriately. The structure has been analyzed for both static and seismic loads. Seismic analysis has been carried out considering the hydrodynamic effects of the contained water. Based on the stress analyses results, the most likely failure modes viz. tensile cracking and compressive crushing of concrete for the various structural elements; caused by the seismic event have been investigated. Further an attempt has also been made to quantify the initial leakage rate and average emptying time for the structure during seismic event after evaluating the various crack parameters viz. crack-width and crack-spacing at the locations of interest. The results are presented with reference to peak ground acceleration (PGA) of the seismic event. It has been observed that, an increase in PGA would result in significant increase in stresses and crack width in the various structural members. Significant increase in initial leakage rate and decrease in average emptying time for the structure has also been observed with the increase in PGA.

• Journal of the Korea Concrete Institute
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• v.29 no.3
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• pp.267-273
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• 2017

Recently, the researches of self-healing concrete technology are being carried out actively due to the advent of importance for the maintenance of concrete structures. A water permeability test has been widely used for the evaluation of self-healing performance. However, it is difficult to compare tests results since there is no standard test method related to the self-healing. A standard method for measuring the crack width does not exist neither though the self-healing performance is significantly influenced by the initial crack width. In this study, the effect of water head and crack width on water flow was investigated using a constant water head permeability test equipment. The correlation equation between the initial crack width and water flow was suggested through the regression analysis of test data, and the predicted crack widths agree well with the real crack widths measured using microscopy.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.7
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• pp.9-15
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• 2019

The purpose of present study is to assess the maximum width of the surface cracks using the histogram analysis of image processing techniques in concrete structures. For this purpose, the concrete crack image is acquired by the camera. The image is Grayscale coded and Binary coded. After Binary coded image is Dilate and Erode coded, the image is then recognized as separated objects by applying Labeling techniques. Over time, dust and stains may occur naturally on the surface of concrete. The crack image of concrete may include shadows and reflections by lighting depending on a surrounding conditions. In general, concrete cracks occur in a continuous pattern and noise of image appears in the form of shot noises. Bilateral Blurring and Adaptive Threshold apply to the Grayscale image to eliminate these effects. The remaining noises are removed by the object area ratio to the Labeled area. The maximum numbers of pixels and its positions in the crack objects without noises are calculated in x-direction and y-direction by Histogram analysis. The widths of the crack are estimated by trigonometric ratio at the positions of the pixels maximum numbers for the Labeled objects. Finally, the maximum crack width estimated by the proposed method is compared to the crack width measured with the crack gauge. The proposed method by the present study may increase the reliability for the estimation of maximum crack width using image processing techniques in concrete surface images.

• Journal of Korean Society of Steel Construction
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• v.17 no.2 s.75
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• pp.195-206
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• 2005

Experimental research was performed on the 6m-6m two-span, continuous composite beams. Background research for the crack width control of continuous composite bridges in the Eurocode-4 is reviewed and equationsfor the calculation of crack width considering tension stiffening are presented. The behavior of the continuous composite beams was investigated using the initial and stabilized cracking process of the concrete slab in tension. Test results showed that the current requirement of minimum reinforcement for ductility in Korea Highway Bridge Design Codes could be reduced. The flexural stiffness of cracked continuous composite beams can be evaluated by the uncracked section analysis until the stabilized cracking stage. An empirical equation for the relationship between the stress of tensile reinforcements and crack width was obtained from the test results.