• Steel and Composite Structures
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• 제15권6호
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• pp.605-621
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• 2013

CFRP strips are widely used nowadays for repair/strengthening or capacity increase purposes. Sharp bending at the ends of the CFRP strips is frequently encountered at these applications. In this study, Reinforced Concrete (RC) beam specimens that were produced with 10 MPa compression strength concrete were strengthened by using bonded CFRP strips with end anchorages to tension region. The parameters that were investigated in this study are the width of the strip, the number of applied fan anchorages and whether additional layer of CFRP patch is used or not at the strip ends. Specimens were strengthened with 100 mm wide CFRP strips with one or two anchorages at the ends. In addition CFRP patch with two and three anchorages at the ends were tested for investigating the effect of the patches. Specimens that were strengthened with three anchorages at the ends with patches were repeated with 60 and 80 mm wide CFRP strips. The most successful result was obtained from the specimen that was strengthened with 80 mm wide CFRP strips with 3 end anchorages and patches among the others at the experimental program. The numbers of anchorages that were applied to ends of CFRP strips were more effective than the width of the CFRP strips onto strength and stiffness of the specimens. Due to limited space at the ends of the strips at most three anchorages could be applied.

• Computers and Concrete
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• 제16권3호
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• pp.415-428
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• 2015

Study on flexural retrofitting of RC beams using external bars with additional intermediate anchorages at soffit is reported in this paper. Effects of varying number of anchorages in the external bars at soffit were studied by finite element analysis using ANSYS 12.0 software. The results were also compared with available experimental results for beam with only two end anchorages. Two sets of reference and retrofitted beam specimens with two, three, four and five anchorages were analysed and the results are reported. FE modeling and non-linear analysis was carried out by discrete reinforcement modeling using Solid65, Solid45 and Link8 elements. Combin39 spring elements were used for modeling the frictional contact between the soffit and the external bars. The beam specimens were subjected to four-point bending and incremental loading was applied till failure. The entire process of modeling, application of incremental loading and generation of output in text and graphical format were carried out using ANSYS Parametric Design Language.

• Computers and Concrete
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• 제10권1호
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• pp.59-78
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• 2012

Although the effect of corrosion of reinforcing bar on the shear behavior of the reinforced concrete (RC) beam had been simulated by tests of the beam with unbonded, half-exposed or whole-exposed tensile steel reinforcements as well as defective stirrup anchorages, theoretical methods to accurately predict remaining capacity of this kind of RC beams, especially shear capacity, are still lacking. Considering the possible position of the critical inclined crack, the actual pattern of strains in the concrete body within the partial length and the proposed compatibility condition of deformations of the RC beam, shear strength of the RC beam with unbonded or exposed tensile steel reinforcements and/or defective stirrup anchorages is predicted. Comparison between the model's predictions with the experimental results published in the literature shows the practicability of the proposed model. Influence of the length of unbonded or exposed tensile steel reinforcements and the percentage of stirrups lacked end anchorages on the shear strength of the RC beam is discussed. It is concluded that, the shear strength of the RC beam with unbonded or exposed tensile steel reinforcements and/or defective stirrup anchorages is greatly influenced by the length of unbonded or exposed tensile steel reinforcements and the percentage of stirrups lacked end anchorages, this influence can be adverse, insignificant or even favourable, dependent on the given parameters of the corresponding normal bonded RC beam.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2010년도 춘계학술대회
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• pp.169-170
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• 2010

울산항은 국내 다른 무역항에 비해 항계 및 정박지가 협소하고, 해상교통 흐름이 복잡하여 해양사고의 발생 개연성이 매우 높은 실정이다, 특히 울산 신항 개발에 따라 입 출항 선박량이 증가할 경우 정박지 부족 현상은 더욱 가중될 것이다. 본 연구에서는 울산항의 정박지 확충을 위해 불가피하게 요구되는 항계 확장 방안을 모색하여 제시하고자 한다. 해당 정박지 면적을 수용할 수 있는 항계 범위를 확정한 후 전문가 그룹에 의한 설문조사를 기초로 적정한 항계 확장 형태를 결정하였다.

• Steel and Composite Structures
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• 제11권3호
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• pp.207-223
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• 2011

The results of an experimental investigation are presented in this paper for retrofitting of shear damaged reinforced concrete beams by using U shaped CFRP strips. The experimental program is consisted of seven shear deficient T cross sectioned 1/2 scale simply supported beam specimens. One beam was used as reference specimen, and the remaining six specimens were tested in two stages. At the first stage, specimens were shear damaged severely, and then were retrofitted by using CFRP strips with or without fan type anchorages. Finally, retrofitted beams were tested up to failure. Three different CFRP strip spacing were used such as 125 mm, 150 mm, and 200 mm. The effect of anchorages on shear strength and behavior of the retrofitted specimens is investigated. CFRP strips without anchorages improved the shear strength, but no flexural failure mode was observed. Specimens showed brittle shear failure due to peeling of CFRP strip from RC beam surface. Shear damaged specimens retrofitted with anchoraged CFRP strips showed improved shear strength and ductile flexural failure. Maximum strains at anchoraged strips were approximately 68% larger than that of strips without anchorages.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2009년도 춘계 학술대회 제21권1호
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• pp.421-422
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• 2009

본 연구는 국산 CFRP 긴장재 및 정착구의 피로거동을 파악하기 위해 반복하중을 재하하여 피로시험을 수행하였다. 압착형 및 부착형 정착구는 피로성능을 만족하였고, 부착형 정착구를 사용하여 CFRP 긴장재의 피로거동을 수행한 결과, 100만, 200만 피로강도는 각각 992, 871MPa로 나타났다.

• 한국항해항만학회지
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• 제34권6호
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• pp.487-492
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• 2010

울산항은 국내 최대의 액체화물 거점항만으로 지속적인 물동량 증가에 대비하여 울산 신항 및 동북아오일허브 개발 등을 본격적으로 추진하고 있다. 그러나 국내 다른 무역항에 비해 항계 및 정박지가 협소하고, 해상교통 흐름이 복잡하여 해양사고의 발생 개연성이 매우 높은 실정이다. 본 연구에서는 울산항의 지형학적인 특성과 선박 교통량을 고려하여 울산항 정박지 확충을 위해 불가피하게 요구되는 항계 확장 방안을 모색하여 제시하고자 한다. 정박지 확충을 위한 항계 확장은 국내 다른 무역항의 정박지 및 항계 면적을 선석 및 통항 교통량 등과 상호 비교하여 확장 범위를 정량화한 후 울산 신항 개발에 필요한 정박지 확대 면적을 산출하였다. 또한 해당 정박지 면적을 수용할 수 있는 항계 범위를 확정한 후 전문가 그룹에 의한 설문조사를 기초로 적정한 항계 확장 형태를 결정하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 학회창립 10주년 기념 1999년도 가을 학술발표회 논문집
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• pp.685-688
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• 1999

The analysis and design of composite girders prestressed by external tendons involve difficulties related to the position of anchorages and the construction sequences. In this paper, the efficiency of the external tendon profiles and the position of anchorages in examined for the internal and external prestressing of statically indeterminate structures. It is shown that strengthening of a prestressed girder can be accomplished using a variety of methods; bonded external prestressing, tendon replacement and unbonded external prestressing.

• Structural Engineering and Mechanics
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• 제47권3호
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• pp.383-399
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• 2013

High-strength strands are widely used as a key structural element in cable-stayed bridges and prestressed concrete structures. Conventional strands for stay cable and tendons in prestressed concrete structures are ${\phi}$15.7mm coated seven-wire strands and ${\phi}15.2mm$ uncoated seven-wire strands, respectively, but the ultimate strengths of both strands are 1860MPa. The objective of this paper is to investigate the tensile behavior of a newly developed ${\phi}15.7mm$ 2,200 MPa coated strand and a ${\phi}15.2mm$ 2,400 MPa uncoated strand according to various types of mono anchorages and to propose appropriate anchorages for both strands. Finite element analyses were initially performed to find how the geometry of the anchor head affects the interaction among the anchor head, the wedge and the strand and to find how it affects the stress distributions in both parts. Tensile tests for the new strands were carried out with seven different types of mono anchorages. The test results were compared to each other and to the results obtained from the tensile tests with a grip condition. From the analysis and the test results, desirable mono anchorages for the new strands are suggested.

• 해양환경안전학회지
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• 제20권4호
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• pp.398-404
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• 2014

우리나라 주요 항만에 규정되어 있는 정박지와 관련한 운영 세칙은 항만마다 정박지 운영 기준이나 정박지 선박수용능력에 대한 단위가 단일화 되어있지 않으며, 동일한 사안에 대해 다른 용어들을 사용하고 있다. 이로 인해 정박지를 운영하거나 이용하고자 하는 당사자들에게 큰 혼란을 주고 있는 상황이다. 본 연구에서는 국내 주요 항만의 정박지 운영 세칙을 검토하여 세칙명, 단위 및 용어의 단일화 방안을 제안하였다. 아울러 정박지 운영상의 혼란을 최소화하기 위하여 외국 주요 항만의 정박지 현황 검토를 통하여 향후 세칙 개정시 정박지 명칭 부여 원칙, 정박지 선박수용능력 단위 및 정박지의 수용가능한 선박 척수의 설정이 이루어지도록 제안하였다.