• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.2
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• pp.697-703
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• 2017

This paper examines the flexure behavior of FRP-concrete composite structure that can replace conventional reinforced concrete structure types. In order to investigate the structural performance and behavioral characteristics in numerical analysis means, ABAQUS, a general purpose finite element analysis program, was utilized for nonlinear finite element analysis, and the various variables and their influences were analyzed and compared with experimental results to suggest values optimized to this composite structure. The concrete damage plasticity model and Euro code for concrete were used. In the implicit finite element analysis, the convergence was ambiguous when geometrical and material nonlinearity were large, so the explicit finite element analysis used in this study was deemed to be appropriate. From the comparison with the experiment about concrete damaged plasticity model, 20mm for the mesh size, $30^{\circ}$ for the dilation angle, $100Nmm/mm^2$ for the value of fracture energy, 0.667 for Kc value, and the consideration of damage parameter were suggested believed to be appropriate. The numerical model suggested in this study was able to imitate the ultimate load and cracking pattern very well; therefore, it is expected to be utilized in research of various new material composite structures.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.6
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• pp.113-119
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• 2016

In this study, the method to predict the lateral response by using strain data is presented on the steel moment frame. For this, the reliability of the proposed method by applying the example of five-story frame structure were verified. Using the strain value of columns, it predicted the lateral response of structure. It is assumed that all of four strain sensors for one column set up and the strain responses of both end of the column are utilized. The lateral response of member is calculated by using the slope deflection method. Also, using the acceleration response of the one layer, the stiffness of the rotation spring located in the supporting point is predicted. As a result, it was effective to understand the lateral displacement and acceleration responses and to predict local damage and location.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.277-280
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• 2008

Reinforced concrete structures have an excellent durability under a good construction and continuous maintenance. But reinforced concrete construction is influenced by atmospheric phenomena and it is creating a deterioration. One of the deterioration cause on concrete is a freezing and thawing action. Freezing and thawing leads to the reduction in concrete durability by the cracking or surface spalling. If we are carried out freezing and thawing, deterioration of reinforced concrete construction will be reduction. Therefore, this study was performed to investigate the flexural behavior of reinforced concrete beams exposed to freezing and thawing cycles. Thee presence of damage and cycles were considered as variablees in this study.

• International Journal of Highway Engineering
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• v.14 no.1
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• pp.17-24
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• 2012

This study evaluated the performance of Korean epoxy asphalt mixtures using several laboratory tests. Four types of epoxy asphalt mixtures were manufactured based on 13mm dense graded asphalt mixtures: three Korean and one Japanese epoxy asphalt mixtures where 20% or 40% of asphalt binder was replaced by epoxy resins. Curing time was determined as 3 and 6 hours for the mixtures containing 40% and 20% of epoxy resins, respectively. From the laboratory tests including wheel tracking, indirect tension fatigue, bending beam, and moisture susceptibility tests, it was concluded that the epoxy asphalt mixtures had superior performance than conventional asphalt mixtures except moisture susceptibility. Also, the performance of the Korean epoxy asphalt mixtures was comparable to the Japanese mixtures. Thermal coefficient, bond strength, and indirect tension tests were conducted to examine the applicability of the Korean epoxy asphalt mixtures to concrete repair. Its adhesion was strong enough to be bonded to surrounding concrete materials and its tensile strength was comparable to the concrete, but thermal expansion coefficient was 5 times greater than the surrounding concrete.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.4
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• pp.98-106
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• 2008

The strengthening in terms of efficiency, easy, economics is very popular method when it is applied to a damaged structures. The purpose of this study develops anchorage system that supports enough strengthening effect without any damage. In addition it is checked whether the method can be conveniently applied to structures. To verify strengthening effect a flexural experiments were performed. Four concrete beams were constructed and tested. Deflections, strains and modes of failure were recorded to examine strengthen of beams. Comparing crack load of each experimental data, yielding load, ultimate load, ductility index, and tendon stress were analyzed.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.77.2-77.2
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• 2010

스크린 프린팅을 이용한 태양전지에서 전극소성 시 알루미늄 후면 전극이 실리콘으로 확산되어 후면전계(Back Surface Field)를 형성한다. 후면전계 형성시 알루미늄과 후면전계 사이에 알루미늄-실리콘 합금이 형성된다. 이 알루미늄-실리콘 합금은 알루미늄 후면전극의 전기전도도 및 휨현상, bead 형성 등에 영향을 끼친다. 본 논문은 알루미늄 페이스트에 첨가된 Glass frit이 알루미늄-실리콘 합금 형성에 끼치는 영향을 관찰하였다. 분산제, 유기바인더, 알루미늄을 섞어 1개의 페이스트를 만들었고, Glass frit을 1%, 2%, 3%, 4%, 5% 씩 첨가하여 총 6개의 알루미늄 페이스트를 만들었다. 절삭손상이 제거된 실리콘 기판의 후면에 알루미늄 페이스트를 스크린 프린팅하여 전극을 소성하였다. 주사전자 현미경(SEM)을 사용하여 시편의 단면사진으로부터 Glass frit 함량에 따른 알루미늄-실리콘 합금층의 변화를 관찰하였다. Glass frit이 첨가되지 않은 페이스트는 소성 후 알루미늄-실리콘 합금이 두껍게 형성되었으나, Glass frit이 첨가된 페이스트는 소성 후 알루미늄-실리콘 합금이 얇게 형성되는 결과를 얻었다. 또한 Glass frit을 첨가함에 따라 표면의 원형 모양의 무늬가 작아지면서 3%부터는 사라지는 것을 확인할 수 있었다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2009.04a
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• pp.304-307
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• 2009

본 논문에서는 3차원 모델링을 이용하여 원공을 갖는 알루미늄 판의 패치 보강효과에 대해 알아보고자 한다. 구조물의 노후화로 인해 높은 응력을 받는 부재의 응력 특이점에서 내구력이 급격하게 저하되거나 때로는 부재의 정적파괴를 유발시키는 원인을 제공한다. 이로 인해 과거에는 손상된 모재에 보강 재료를 연결시키기 위하여 리벳 또는 볼트와 같은 기계적 연결을 통해 보강하였으나 최근에는 접착패치보강 기법이 그 주류를 이루고 있다. 패치 보강시 일면 패치 보강으로 인하여 면외 휨 효과가 발생된다. 판의 두께 방향에 따른 응력집중계수를 별도로 분석하였다. 기존의 3차원 솔리드 요소는 해의 정확성은 뛰어난 반면에 상당한 컴퓨터 시간을 요구하는 단점을 가지고 있다. 이러한 문제를 극복하기 위해서, 본 논문에서는 각 층의 변위장을 2차원 형상함수와 1차원 형상함수의 조합으로 구성하여, 면내거동에 대한 p-세분화와 면외거동에 대한 p-세분화를 분리시키는 방식을 취한다. 또한, 에너지 함수의 적분시 Gauss-Lobatto 적분법을 사용하여 절점의 위치에서의 응력점을 구하는 경우, 외삽과정을 계산하는 단계를 생략하면서도, 해의 정확성 측면에서는 거의 차이가 없기 때문에 좀 더 효율적인 수치적분이 될 수 있다.

• Journal of Korean Society of Steel Construction
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• v.13 no.4
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• pp.337-349
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• 2001

This study present an optimum deck and girder system design for minimizing the life-cycle cost (LCC) of orthotropic steel deck bridges. The problem of optimum LCC design of orthotropic steel deck bridges is formulated as that of minimization of the expected total LCC that consists of initial cost, maintenance cost, expected retrofit costs for strength, deflection, and fatigue. To demonstrate the effect of LCC optimum design of orthotropic steel deck bridges, the proposed optimum LCC design is compared with the conventional method for orthotropic steel deck bridges design. From the numerical investigations, it may be positively stated that the proposed optimum design procedure for orthotropic steel deck bridges based on the LCC will lead to more rational, economical and safer design.

• Journal of the Korea institute for structural maintenance and inspection
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• v.4 no.4
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• pp.201-210
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• 2000

The Rehabilitation and repair of structurally deteriorated reinforced concrete structure become more necessary as time goes by. The goal of this study is that provide the data about flexural retrofitted effect of RC beam strengthened by Steel Plate. In order to provide the data, 6 specimens were manufactured and divided with standard specimen and damaged degree A, B, C. Division of damaged A, B, C is based on deflection and degree of crack. In the determination of deflection and degree of crack, we loaded standard specimen to failure under two-point bending to find yielding load and failure load, and then we found deflections and degree of crack that correspond to 75%, 100%, 105% of the yielding load of standard specimen respectively. When we are compared with standard specimen and strengthened specimens, we founded from the experimental results that flexural capacity of structurally damaged beam strengthened by Steel Plate incremented highly, ductility was decreased, and energy absorbtion capacity was almost same.

• Journal of the Earthquake Engineering Society of Korea
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• v.26 no.6
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• pp.255-265
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• 2022

In order to determine fragility curves, the limit state of piers for each damage level is suggested in this paper based on the previous test results in Korea, including our test results. In previous studies, the quantitative measures for damage levels of piers have been represented by curvature ductility, lateral drift ratio, or displacement ductility. These measures are transformed to lateral drift ratios of piers for consistency, and the transformed values are compared and verified with our push-over test results for flexural RC piers with a circular cross-section. The test specimens are categorized concerning the number of lap-splices in the plastic hinge region and whether seismic design codes are satisfied or not. Based on the collected test results in Korea, including ours, the lateral drift ratio for each pier damage level is suggested.