• International Journal of Highway Engineering
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• v.15 no.1
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• pp.1-9
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• 2013

PURPOSES: The purpose of this study is to evaluate physical properties, durability, fatigue resistance, and long-term performance of poly-urethane concrete (PU) which can be possible application of thin layer on long-span orthotropic steel bridge and to check structural stability of bridge structure. METHODS : Various tests of physical properties, such as flexural strength, tensile strength, bond strength and coefficient of thermal expansion tests were conducted for physical property evaluation using two types of poly urethane concrete which have different curing time. Freezing and thawing test, accelerated weathering test and chloride ion penetration test were performed to evaluate the effect of exposed to marine environment. Beam fatigue test and small scale accelerated pavement test were performed to assess the resistance of PU against fatigue damage and long-term performance. Structural analysis were conducted to figure out structural stability of bridge structure and thin bridge deck pavement system. RESULTS: The property tests results showed that similar results were observed overall however the flexural strength of PUa was higher than those of PUb. It was also found that PU materials showed durability at marine environment. Beam fatigue test results showed that the resistances of the PUa against fatigue damage were two times higher than those of the PUb. It was found form small scale accelerated pavement test to evaluate long-term performance that there is no distress observed after 800,000 load applications. Structural analysis to figure out structural stability of bridge structure and thin bridge deck pavement system indicated that bridge structures were needed to increase thickness of steel deck plate or to improve longitudinal rib shape. CONCLUSIONS: It has been known that the use of PU can be positively considered to thin layer on long-span orthotropic steel bridge in terms of properties considered marine environment, resistance of fatigue damage and long-term performance.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.297-302
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• 2000

This paper presents the effect of diaphragm spacing ratio(depth to span) on behavior and capacity of composite steel-concrete structures of sandwich system. Numerical analysis has been performed variety diaphragm ratio, behavior and load condition. As a results of this study, in case of shear behavior and concentrated load, the capacity of structure such as yielding and ultimate load improve according to diaphragm ratio because of concrete confining effect by steel plate and stress redistribution by diaphragm. But in case of bending behavior or uniform load, it proved that diaphragm ratio don't influence on behavior and capacity of composite structures of sandwich system.

• Journal of the Korean Ceramic Society
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• v.47 no.4
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• pp.276-282
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• 2010

There are the impregnating layer formation by surface protective materials or impregnants and the adhesion method by polymer, FRP sheet or steel plate in the surface protective method of concrete structure. The surface impregnation method by impregnants improves the durability of concrete structure by modifying the structure of the concrete surface and also have a merit that can be shortly applied in place without the decrease of concrete surface appearance and is easily applied again. This study is interested in manufacturing the concrete surface impregnants including lithium and potassium silicate for the repair of the exposed concrete and the color concrete requiring the advanced function in view of the concrete appearance. The durability and porosity properties was tested for the review of application. The result of this study show that the effective content of silicate ranges 5 to 20% and the separate application of the first impregnant and the second impregnant is effective for the optimum performance. The adhesion in tension is slightly increased but the reinforcement of concrete substrate is slight. So, the concrete impregnant of this study is more desirable for the improvement of durability rather than the reinforcement.

• Journal of the Korea Institute of Building Construction
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• v.14 no.1
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• pp.1-10
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• 2014

The SC structure can have relatively liberal sectional surfaces, and allows modularization for pre-forming in factories and structural stability. It can be used for the shear walls in the core of general buildings or the structural members for parking buildings. In the future, it could be applied to moving large bus terminals, and widely used for general industrial structures as it can expedite the process compared to other methods. This study examined the applicability of SC structures to the retaining walls of a parking building and reviewed its economic value by comparing its construction term, quality control benefits, and cost compared to RC structures. It was found that SC structures are about 1.6-1.7 times more expensive than RC structures in terms of the cost of fabrication and installation. However, the construction term can be reduced by 27% to save indirect costs for constructors, as well as the cost of removing molds and material loss required when installing RC structures.

• Structural Engineering and Mechanics
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• v.74 no.5
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• pp.657-670
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• 2020

Due to the high compressive and tensile strength of ultra-high performance concrete (UHPC), UHPC used in steel concrete composite structures provided thinner concrete layer compared to ordinary concrete. This leaded to the headed stud shear connectors embedded in UHPC had a low aspect ratio. In order to systematic investigate the effect of headed stud with low aspect ratio on the structural behaviors of steel UHPC composite structure s this paper firstly carried out a test program consisted of twelve push out specimens. The effects of stud height, aspect ratio and reinforcement bars in UHPC on the structural behaviors of headed studs were investigated. The push out test results shows that the increasing of stud height did not obviously influence the structural behaviors of headed studs and the aspect ratio of 2.16 was proved enough to take full advantage of the headed stud strength. Based on the test results, the equation considering the contribution of weld collar was modified to predict the shear strength of headed stud embedded in UHPC. The modified equation could accurately predict the shear strength of headed stud by comparing with the experimental results. On the basis of push out test results, bending tests consisted of three steel UHPC composite slabs were conducted to investigate the effect of shear connection degree on the structural behaviors of composite slabs. The bending test results revealed that the shear connection degree had a significantly influence on the failure modes and ultimate resistance of composite slabs and composite slab with connection degree of 96% in s hear span exhibited a ductile failure accompanied by the tensile yield of steel plate and crushing of UHPC. Finally, analytical model based on the failure mode of composite slabs was proposed to predict the ultimate resistance of steel UHPC composite slabs with different shear connection degrees at the interface.

• Journal of Korean Society of Steel Construction
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• v.13 no.5
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• pp.503-511
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• 2001

Structures are designed against earthquakes and reinforced concrete shear walls or steel bracings are usually used as aseismic resistant element. However their hysteretic characteristics in plastic region ductility and capacity of energy absorption are not always good. Besides their stiffness is so rigid that structure designed by static analysis is occasionally disadvantageous. when dynamically analized. Generally a steel plate subjected to shear force has a good deformation capacity Also it has been considered to retain comparative shear strength and stiffness Steel shear wall can be used as lateral load resistant element for seismic design. However there was little knowledge concerning shear force-deformation characteristics of steel plates up to their collapse state In this study a series of shear loading tests of steel plate collapse state. In this study a series of shear loading tests of steel plate surrounded by vertical and horizontal ribs were conducted with the parameters of D/H ratios rib type and the loading patterns. The test result is discussed and analyzed to obtain several restoring characteristics. that is shear force-deformation stiffness and yield strength etc.

• Structural Engineering and Mechanics
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• v.19 no.6
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• pp.653-677
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• 2005

Concrete filled steel tubular columns (CFT) are widely used in civil engineering works, especially in large scale of works because of high strength, deformation, toughness and so on. On the other hand, as a kind of strengthening measure for seriously damaged reinforced concrete piers of viaduct in Hansin-Awaji earthquake of Japan in 1995, reinforced concrete piers were wrapped with steel plate. Then, a new kind of structure appeared, that is, reinforced concrete filled steel tubular column (RCFT). In this paper, compression test and bending-shearing test on RCFT are carried out. The main parameters of experiments are (1) strength of concrete, (2) steel tube with or without rib, (3) width-thickness ratio and (4) arrangement of reinforcing bars. According to the experimental results, the effect of parameters on mechanical characteristics of RCFT is analyzed clearly. At the same time, strength evaluation formula for RCFT column is proposed and tested by experimental results and existed recommendations (AIJ 1997). The strength calculated by the proposal formula is in good agreement with test result. As a result, the proposed evaluation formula can evaluate the strength of RCFT column properly.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.331-334
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• 2003

Since regulation or specification for the reinforcing method are quite ambiguous, structural design for the reinforcement can be subjectively and arbitrarily conducted. Thus, reasonable limitation and guide for the quantity of the reinforcement are required for the safe use of the structure after repair. In order to guarantee the safety of the structural member several items should be considered; reinforcing limit to avoid the brittle failure, least required strength of the existing member before reinforcement in order not to fail under the new serviceability load condition when reinforcing steel plates or CFRP sheets are harmed or subjected to fire.

• Journal of the Korea Concrete Institute
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• v.29 no.2
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• pp.209-216
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• 2017

One of the important considerations in structural designing the flat plate system is ensuring the resistance to punching shear caused by axial loads and the ductile ability to follow horizontal deformation under earthquake. In this study, the ECC (Engineered Cementitious Composite) has been placed in the critical section zone of punching shear at slab-column joint to improve ductility and the advanced details of shear reinforced area nearby critical section zone has been developed using stud and steel fiber. The shear performance tests were performed on the specimens with parameters of fiber type mixed with ECC, stud and steel fiber set into the shear reinforced area in which the failure pattern, joint strength, displacement and strain of the specimen were compared and analyzed. The test results showed that the strength and ductility of specimens with ECC applied to joint were better than those of RC flat plate system. Also, the shear reinforcement effect of stud and the ductility improvement of steel fiber concrete were confirmed in the shear reinforcement area.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.5A
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• pp.277-287
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• 2012

The shear wall with openings built with reinforced concrete (RC) have been elaborately studied by many researchers, whereas the steel plate concrete (SC) wall structure has not been investigated as much. The recent SC wall structures developed in Korea have been partly applied to nuclear power plant structures, although its design specification or guideline for the SC wall structure with openings has not been completed yet. This study based on numerical analysis evaluates the effects of opening on the structural resistance of the SC structure in nuclear power plant. As a result from nonlinear analysis, since the strengthening for openings significantly affect the overall strength of SC wall, the openings should be considered to strengthen them around adjacent area. It is also proved that the strengthened openings have the sufficient resistance and ductility regardless their size, shape, location, and quantity.