• The Korean Journal of Rheology
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• v.9 no.4
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• pp.151-162
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• 1997

다층 구조를 갖는 고무/아크릴 충격보강제가 poly(methyl methacrylate) (PMMA)/ 충격보강제 블렌드의 몰폴로지와 유변학적 성질에 미치는 영향을 고찰하였다. TEM으로 측 정한 블렌드 내의 충격보강제 몰폴로지는 그 함량에 관계없이 균일한 크기의 구형을 이루는 것으로 나타났으며 파괴 단면의 SEM 측정으로부터 충격보강제와 매트릭스 수지와의 강한 결합력을 확인할수있었다. 블렌드의 유변물성 측정 실험에서는 충격보강제 함량이 복합 점 도에 크게 영향을 준 반면, capillary rheometer로부터 얻은 정상상태 점도에는 별 영향을 주지않음이 확인되었다. 특히 동적응력 실험의 고진동 주파수 영역에서는 일정 충격보강제 함량이상 일 때 충격보강제 자체의 점도와 근사해졌으며 이와같은 현상을 충격보강제의 shell 분자 상호간 또는 매트릭스 분자와의 엉킴에서 비롯되는 물리적인 상호 작용측면에서 설명해보았다. 또한 실험 결과를 Palierne[16]의 비상용성 블렌드계의 이멀젼 모델과 비교한 결과 상당한 차이를 확인할수 있었으며 이러한 차이는 위에서 언급한 shell 분자 상호간 또 는 매트릭스 분자와의 엉킴에 기인한다고 추정된다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.2
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• pp.60-68
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• 2017

This study was made to examine the motion characteristics according to the reinforcement of the reinforcement length and stiffener reinforcement for shear reinforcement to the foundation structure reinforced with shear reinforcement steel plate. Experimental study was made after specimen was installed on the ground as the same as in the practical site. Reinforcement lengths of the steel for shear reinforcement are divided into 1,000 mm, 1,200 mm and 1,400 mm in the specimen and as for reinforcement method of the stiffener, 4 stiffeners with interval of 100mm reinforced with the same materials as the shear reinforcement were manufactured for the experiment. Considering result of the experiment, it is expressed that no effect of the stiffener reinforcement was found and regarding the reinforcement length of shear reinforcement material the crossed point of the two converted lines of the value that the shear force is expressed in the bearing power in the expanded dangerous section and the value that the shear capacity receivable by the reinforcement materials in the dangerous section is proposed as effective reinforcement length.

• Proceedings of the KAIS Fall Conference
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• 2011.05a
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• pp.474-477
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• 2011

본 논문에서는 내진보강공법의 내진성능향상을 평가하기 위하여 진동대실험을 실시하였다. 실험 구조체는 비보강, 보강 구조체로 각각 실규모 크기의 구조체를 2개 제작하였다. 기둥 상, 중, 하부 및 보에 각각 Strain게이지, 가속도계를 설치한 후 설계펙트럼가속도 0.15g의 30~150%까지 가속도를 증가 시키면서 실험을 수행하였다. 그 결과 비 보강 구조체는 0.2g에서 최대 80cm균열이 발생하였으나 보강 구조체는 균열이 발생하지 않았다. Strain의 변화량에서는 비 보강이 보강보다 최대 1700%크게 나타났다. 가속도의 변화량은 비 보강이 176%크게 나타났다. 진동대 실험결과 본 내진보강공법이 내진성능향상에 지대한 영향을 주고 있음이 증명되었다.

• Journal of the Korean GEO-environmental Society
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• v.9 no.2
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• pp.67-74
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• 2008

Many industrialized countries of the world have many problems about the reuse of waste landfill area because of the increase of terminated waste disposal landfill. Especially, the effective use of the terminated waste disposal landfill nearby the urban area has been demanded, because of the lack of the usable land. However, in case of the construction of the building on such a landfill, ground settlement and reduced bearing capacity would be occurred without ground stabilization and proper reinforcement. This study is to evaluate the applicability of geosynthetics for the increment of bearing capacity of solid waste landfill ground. A numerical simulation has been undertaken to model a layer of weathered soil overlaying a layer of geosynthetic reinforcement and waste disposal ground. The proposed analytical model can be used to obtain surface settlement characteristic in the two-dimensional deformation related reinforcement.

• Journal of the Korean GEO-environmental Society
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• v.23 no.4
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• pp.29-39
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• 2022

In order to solve the serious traffic congestion in seoul metropolitan city, large-scale underground space development such as underpasses, deep underground roads, and GTX (Great Train eXpress) is being carried out. In order to minimize the impact of the adjacent seoul metro line A pier foundation and stability due to the construction of the underground road in Seoul, earth retaining structures were reinforced and the foundation was reinforced as well. In this study, three-dimensional finite element mehtod analysis was performed to evaluate the effect on adjacent construction and to review the stability of the underpass excavation work. The reinforcement effect was quantitatively analyzed through numerical analysis. As a result of the analysis, compared to the result of performing the existing reinforcement when overlapping CIP and ground reinforcement grouting were performed, the displacement of the earth retaining structures was reduced by more than 50%, and stress of the foundation piles were also reduced by more than 45%. Based on the analysis of the numerical analysis results, it was confirmed that the displacement of the walls of earth retaining structures during adjacent construction should be strictly controlled.

• Journal of the Earthquake Engineering Society of Korea
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• v.5 no.2
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• pp.49-57
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• 2001

본 연구의 목적은 유사동적실험에 의한 섬유보강 원형 RC교각의 내진성능평가를 위한 연구로서 수원시에 위치한 내진교량인 하길교를 대상모델로 하였으며, 도로교 표준시방서의 내진설계규정이 적용되지 않은 비내진교각시험체 2본 및 내진성능향상을 위한 섬유보강시험 4본, 즉 총 6본에 대하여 유사동적실험을 수행하였다. 보강공법으로는 유리 탄소섬유 보강공법을 사용하였으며, 실험변수로는 입력지진동, 섬유고방유무로 하였다. 그리고 내진성능평가 방법은 입력 및 소산에너지, 변위 연성도가 분석되었다. 본 실험의 결과 유리 섬유로 보강된 비내진시험체의 변위연성도 KHC인공지진파에 대하여 7.7~9.0정도의 값으로 충분한 내진성능을 확보하고 있는 것으로 평가되었다.

• Journal of Korean Tunnelling and Underground Space Association
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• v.14 no.5
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• pp.453-467
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• 2012

Usage of underground space is increasing at metropolitan city. More than 90% of flood damages have occurred at downtown of metropolitan cities. In order to prevent and/or minimize the flood-induced damage, an underground rainwater detention cavern was proposed to be built underneath existing structures. As for underground caverns to be built for flood control, multi-caverns will be mostly adopted rather than one giant cavern because of stability problem. Because of the stress concentration occurring in the pillars between two adjacent caverns, the pillar-stability is the Achilles' heel in multi-caverns. So, a new pillar-reinforcing technology was proposed in this paper for securing the pillar-stability. In the new pillar-reinforcing technology, reinforced materials which are composed of a steel bar and PC strands are used by applying pressurized grouting, and then, by applying the pre-stress to the PC strands and anchor body. Therefore, this new technology has an advantage of utilizing most of the strength that the in-situ ground can exert, and not much relying on the pre-cast concrete structure. The main effect of the pressurized grouting is the increase of the ground strength and more importantly the decrease of stress concentration in the pillar; that of the pre-stress is the increase of the ground strength due to the increase of the internal pressure. In this paper, ground reinforcing effects were verified the stress change in pillar is obtained by numerical analysis at each construction stage. From these results, the effects of pressurized grouting and pre-stress are verified.

• Geotechnical Engineering
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• v.2 no.1
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• pp.45-54
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• 1986

An experimental study was carried out in the laboratory on a model of a reinforced earth retaining wall to provide the empirical data for the rational design and the construction methods on a reinforced earth retaining wall. Observed measurements included the variation of tension in the aluminium foil reinforcing strips was monitored by electrical resistance strain gauges pasted on its at different stages of construction. In addition, the lateral movement of the wall was measured by dial gauges and the mode of collapse of the wall was investigated. The measured values are discussed in comparison with the results of the existing studies of the reinforced earth retaining wall. A significant result of the experiments is that the variation of tension in reinforcing strips is non-linear with the maximum tension occuring close to wall face. Attachment of reinforcement to wall increases the stability against overturning.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.1
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• pp.845-852
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• 2015

This study examined the flexural strength of CFS reinforced concrete beams with various load histories. The RC beams to be reinforced by CFS have undergone various loading histories but neglecting the loading history results in a few problems in structural safety and cost. Structural behavior of CFS-strengthened RC beams were analyzed considering the strain status of RC beams under loads at the time of CFS strengthening. Nonlinear section analysis showed that the flexural strength of CFS-strengthened RC beams depends on the load history of the RC beams. From the result of this analysis, the flexural strength of a CFS-strengthened concrete beam is affected considerably by the load history and should be considered in CFS reinforcement.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.8
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• pp.3745-3751
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• 2011

In this study flexural strength of damaged concrete beams reinforced by CFS is analysed. Nonlinear section analysis is used to include stress status of tension bars and compressive concrete under loads acting on the original member at the time of strengthening. Calculated flexural strength is compared with Sin-Hong formula which is frequently used in CFS reinforcement design. Nonlinear analysis with variation of the number of strengthening CFS, the ratio of tensile reinforcement, the ratio of section dimension shows that the flexural strength of CFS reinforced beams much depends on reinforcing stage. From the result of this analysis, the flexural strength of CFS reinforced concrete beam is reduced according to the magnitude of pre-loaded service loads.