• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.2
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• pp.179-188
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• 2011

Steel structures have been allowed to have fatigue damage tolerance in fact. If it would be assessed whether fatigue crack is growing or not and How fast fatigue crack is propagating, we should make a rational decision on methods and a period of reinforcement in the maintenance. In this study, fatigue crack growth tests on two kinds of through-thickness cracked steel plates and a out-of-plane gusset welded joint were conducted to evaluate fatigue crack growth rate using the COD(Crack Opening Displacement), and COD measurement using strain gauges was examined to offer a practical method. As a result, we proposed a reasonable assessing method for fatigue crack growth rate using the COD and it was experimentally proved practical to estimate the COD through measuring strains.

• 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 Academia-Industrial cooperation Society
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• v.8 no.5
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• pp.1173-1178
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• 2007

A laboratory investigation is conducted to characterize and quantity fatigue life of continuously reinforced concrete pavement with initial cracks. Four specimens scaled were made based on results of finite-element analyses and stress-strain curve comparisons. Static tests were firstly performed to obtain magnitudes of static failure loads and to predict crack patterns before fatigue tests. The fatigue lives measured in the study were compared based on the initial crack spacing. The comparison indicates that the fatigue lives of most specimens increases with increasing the initial crack spacing. The results obtained in the study can be used for maintenance and retrofit of the continuously reinforced concrete pavements.

• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.1
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• pp.243-250
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• 2005

In elevated irrigation aquaducts, one can observe a common damage pattern. That is, cracks, and crushing of concrete are usually repeated at a certain interval even if no faults are found in the design and construction of the structures. To investigate the causes of this damage, longitudinal deformations of several aquaducts have been measured. The analysis of the measured data suggests that the damages are mainly caused by cumulative repetition of extension and contraction due to temperature changes.

• International Journal of Highway Engineering
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• v.6 no.4 s.22
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• pp.101-108
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• 2004

Asphalt overlay method is a general method to extend the of life old concrete pavements. However, reflection cracks are the typical problem of the AC overlay on distressed concrete pavement. Joint sealing, stress absorbtion layer have been used to prevent reflection cracks however partial success of to delay the timing of reflection cracking was recognized. Reflection crack problem can be eliminated by using rubblization method, which crush concrete pavement slab into piece of aggregate size that can be used base material. Previous research on rubblization method indicated that the size of rubblized PCC ranged 40-70mm at upper layer, and more than 100mm at lower layer. In this study, the adequate depth of rubblized PCC that ran prevent reflection cracking of AC overlay is estimated base on the simulation test of reflection cracking with 0, 10, 20cm rubblized PCC base.

• Journal of Ocean Engineering and Technology
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• v.22 no.3
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• pp.89-95
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• 2008

Fatigue cracked components often needs to be repaired during service. Standard repair schemes involve strengthening the component by connecting reinforcing members by means of rivets or welding by reducing the crack-tip stress intensity factors. Recent technological advances in fiber reinforced composite materials and adhesive bonding have led to the development of efficient repair schemes. In this study, the influence of various shape parameters on fatigue crack growth in the CCT type uniform thickness plates and the thin-ta-thick type stiffened panels repaired with woven fabric type Kevlar-Epoxy composite patch are studied experimentally.

• Magazine of the Korea Concrete Institute
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• v.18 no.1 s.90
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• pp.56-61
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• 2006

• Magazine of the Korea Concrete Institute
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• v.16 no.5 s.82
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• pp.44-48
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• 2004

• Magazine of the Korea Institute for Structural Maintenance and Inspection
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• v.20 no.1
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• pp.31-37
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• 2016

• Journal of the Korean Recycled Construction Resources Institute
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• v.2 no.3
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• pp.255-264
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• 2014

This study analyzes the cause and the repairing method of water leak by parts of basement parking lot which is recorded to have a high defect frequency in apartment buildings. It has been assessed that the cause of water leakage on the first floor upper substrate is due to such factors as landscaping and weights. During construction or through other cases, it has been determined that cracks were produced in the apartment structure because the structure was weak and exposed to the effects of the substrate movement. The base floor and underground external walls are areas that are exposed to water pressure (uplife pressure), thus in normal cases the rear surface repair of the structure using sythetic rubberized polymer gel should be considered as an effective method. However, in cases where application of waterproofing layer is required in the structure due to high water pressure, using asystolic cement milk grout to form the waterproofing layer and applying water-swelling acrylic material into the cracked areas is considered to be highly effective.