• Journal of Korean Association for Spatial Structures
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• v.7 no.1 s.23
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• pp.79-85
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• 2007

Steel plate bonding method with epoxy is common applied to repair and strengthen RC structures, but Steel is apt to corrode quickly, hard to manufacture and heavy. To overcome these defects, it is carried out research on strengthening RC structures with FRP(Fibre Reinforced Polyrner/Plastic) FRP is generally used in the shape of Plate or Sheet, but it has weak point such as premature failure, difficult work. To cope with these problem, NSMR(Near Surface Mounted Reinforcement) which uses CFRP in the shape of Rod is proposed and carried out active research on strengthening effect of variables such as quantity, anchorage length and space of CFRP-Rod. Strengthening with CFRP-Rod is carried out under loading to some degree in fact, and so the amount of pre-loading is selected as variable in this research. The amount of pre-loading is chosen in proportion to nominal strength of non-strengthened specimen with CFRP-Rod.

• Journal of the Korea Institute of Building Construction
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• v.24 no.1
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• pp.23-34
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• 2024

This research aims to assess the flexural bonding efficacy of polymer-cement composites(PCCs) in mending cracks within reinforced concrete(RC) structures. The study involved infilling PCCs into cement mortar cracks of varying dimensions, followed by evaluations of enhancements in flexural adhesion and strength. The findings indicate that the flexural bond performance of PCCs in crack repair is influenced by the cement type, polymer dispersion, and the polymer-to-binder ratio. Specifically, the use of ultra-high early strength cement combined with silica fume resulted in an up to 19.0% improvement in flexural bond strength compared to the application of ordinary Portland cement with silica fume. It was observed that the augmentation in flexural strength of cement mortar filled with PCCs was significantly more dependent on the depth of the crack rather than the width. Furthermore, PCCs not only acted as repair agents but also as reinforcement materials, enhancing the flexural strength to a certain extent. Consequently, this study concludes that PCCs formulated with ultra-high early strength cement, various polymer dispersions, silica fume, and a high polymer-to-binder ratio ranging from 60% to 80% are highly effective as maintenance materials for crack filling in practical settings.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.2
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• pp.161-169
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• 2011

Two-way slabs reinforced with high-performance steels, which have several practical advantages of a reduction of congestion in heavily reinforced members, savings in the cost of labor and repair, the higher corrosion resistance, and a reduction of construction time, were constructed and tested. The influences of the flexural reinforcement ratio, concentrating the reinforcement in the immediate column region, and using steel fiber-reinforced concrete (SFRC) in the slab on the punching shear resistance and post-cracking stiffness were investigated, and compared with the punching shear test results of the slabs reinforced with conventional steels and GFRP bars. In addition, the strain distribution of flexural reinforcements and crack control were investigated, and the effective width calculating method for the average flexural reinforcement ratio was estimated. The use of high-performance steel reinforcement increased the punching shear strength of slabs, and decreased the amount of flexural reinforcements. The concentrating the top mat of flexural reinforcement increased the post-cracking stiffness, and showed better strain distribution and crack control. In addition, the use of SFRC showed beneficial effects on the punching shear strength and crack control. It was suggest that the effective width should be changed to larger than 2 times the slab thickness from the column faces.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.10a
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• pp.219-223
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• 1995

Since the mid of 1970's, the construction of infrastructure has been booming and accelerating to keep up with rapid economic growth. Fast achievement of most construction activities has caused unfavorable effects of civil petitions associated with damages and nuisances due to last hasty works. it is well known that the falling down of Sungsoo bridge and the collapse of Sampoong department and other structures have occurred because of the construction not conforming with the specification, and thereby incurred enormous loss of life and property. Now a days. a periodic inspection and maintenance have been strongly interested on aged RC structures, of repair and reinforcement technique in the country, most repairing and reinforcing works have been performed on the basis of the guidance of few experienced local company in this field.

• Structural Engineering and Mechanics
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• v.27 no.3
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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.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.253-258
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• 2000

Recently, the area of design optimization, especially structural optimization, has been and to be a continuous active area of research. And the design optimizations of port facilities have been achieved by many other civil engineers. But the design optimization of port facilities were limited to the design optimization of the breasting dolphin. This paper invested the design optimization of mooring pier and the foundations of mooring pier was suggested considering the convenience of repair and reinforcement work. The mooring pier devised with prestressed precast concrete panel and rigid frame welded wide flange beam to steel pipe pile. To accomplish the design optimization of mooring pier, the Augmented Lagrangian Multiplier Method(ALM) of ADS(Garret N. Vanderplaats) optimization routine, BFGS method as optimizer and Golden Section Method as one dimensional search were utilized. As a result, thirty percent of material cost for construction was reduced by design optimization. The tensile stress of concrete panel and bottom flage was critical constraints under service load. So, using high strength concrete and steel will be economical. And lots of initial values must be invested to accomplish the design optimization in design procedures.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.3172-3179
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• 2011

Several materials using polymer-portland-cement concrete have developed to have not only strength of attachment with body, but also waterproof function and strong anti-sodium chloride properties. Especially, in case of railway, unlike other public transportation, it is very difficult to doing the repair and reinforcement work of structure during service time. Therefore, the development and study of materials having characteristics of structural strength, unification behavior with body, and resistance of crack are very important. Accordingly, the characteristic of material of polymer based concrete is indicated compared with the experiment and analysis through this study, and suggested application to railway tunnel, bridge, and concrete track structure.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.1185-1192
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• 2001

This paper reviews available techniques for monitoring corrosion of steel in concrete. The need for early detection and diagnosis of corrosion related deterioration in reinforced structures is widely acknowledged. This is particularly important in reinforced concrete structures on account of the economic and social significance of the problem. The current generally used on-site procedure for corrosion monitoring of reinforced structures employs a method of half-cell surface potential measurements. While the technique has provided a useful means of delineating areas of high or low corrosion risk, there are difficulties in its use and interpretation when assessing rates of deterioration. Electrochemical techniques are by far the most suitable for corrosion monitoring purpose and meet most of the requirements. The aim of this paper is to describe the electric resistance sensor(ER sensor) and electrochemical techniques employed to monitor and estimate corrosion rates of reinforcement. Early detection and diagnosis of corrosion hazards allows preventive measures to be taken, hence the typically expensive repair of severely deteriorated structures can be avoided.

• Journal of Chest Surgery
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• v.22 no.6
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• pp.1088-1091
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• 1989

Foramen of Morgagni hernia is the least common type of all congenital diaphragmatic hernias. These foraminal hernias result from a congenital defect in the development or attachment of the diaphragm to the sternum and costal arch. They occur most commonly on the right side, possibly because of pericardial reinforcement of the left. In our case, occurred on the right side and the contents of the hernial sac were omental fat and a part of transverse colon. We performed transthoracic approach for reduction and repair of foraminal hernia with ligation and interrupted mattress sutures of the margin of the defected diaphragm to the posterior part of the sternum and costal cartilage. The postoperative course was uneventful except posttraumatic delirium and discharged at 21st postoperative day.

• Journal of Korean Association for Spatial Structures
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• v.4 no.4 s.14
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• pp.7-14
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• 2004

The analysis method of stabilizing process and its program regarding large spatial structural systems are described in this paper. In this paper, the analysis of stabilizing process of the example structures, namely Olympic Fencing Arena, is performed and the jacking force of stabilizing process is proposed, and the characteristics of structural behavior is investigated. This result of research is applied to the design and construction of the actual structures and the reliability of the analysis is verified through comparison of the analysis results and the measured results in the field. When the analytical results is compared with the actual structural behavior, there is a little difference, but it is thought that the analysis results are quite reliable because it is very similar to the measured values in spite of construction and measurement errors.