• Geomechanics and Engineering
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• 제31권6호
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• pp.573-582
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• 2022

The geometry of the gravity-type anchorage changes depends on various factors such as the installation location, ground type, and relationship with the upper structure. In particular, the anchorage geometry embedded in the ground is an important design factor because it affects the pull-out resistance of the anchorage. This study examined the effect of four parameters, related to anchorage geometry and embedded ground conditions, on the pull-out resistance in the gravity-type anchorage through two-dimensional finite element analysis, and presented a guide for major design variables. The four parameters include the 1) flight length of the stepped anchorage (m), 2) flight height of the stepped anchorage (n), 3) the anchorage heel height (b), and 4) the thickness of the soil (e). It was found that as the values of m increased and the values of n decreased, the pull-out resistance of the gravity-type anchorage increased. This trend is related to the size of the contact surface between the anchorage and the rock, and it was confirmed that the value of n, which has the largest change rate of the contact surface between the anchorage and the rock, has the greatest effect on the pull-out resistance of the anchorage. Additionally, the most effective design was achieved when the ratio of the step to the bottom of the anchorage (m) was greater than 0.7, and m was found to be an important factor in the pull-out resistance behavior of the anchorage.

• 수산해양교육연구
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• 제21권2호
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• pp.291-305
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• 2009

As you known well, Ulsan port is very famous for handling chemical products which occupies about 80% of quantities of all Korean ports. Many ship's operators prefer to handle liquid cargo es at proper anchorages instead of the berth for saving port expenses. Ulsan M-10 anchorage was assigned for handling liquid cargoes, however this anchorage's space is restricted by the oil pipeline which lays under seabed about 400m off from the center of M-10 anchorage, for which we have to consider of the external force and counter force for keeping the safety of anchoring. Where, external force is induced by wind, tidal currents and wave while counter force is induced by holding power of anchor/chain. In this study, author evaluated a method to analyze theoretically the limit of external force condition up to which an anchoring ship can keep her position without dragging, and for which applied to many kinds of combined Ships as mother ship of 50,000 DWT Tanker and 4 sizes of Tanker as alongsided ship.

• 해양환경안전학회지
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• 제22권5호
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• pp.380-388
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• 2016

본 연구는 울산항의 정박지 규모의 적정성을 평가하기 위한 방법을 제시하고, 이를 통해 현재 뿐만 아니라 항만개발에 따른 미래의 정박지 규모의 적정성을 분석하는데 그 목적이 있다. 이를 위해 울산항의 정박지 적정성 평가를 위한 정박지 가동률 개념을 제시하였다. 그리고 이 가동률 개념을 울산항의 2014년 정박지에 적용하여 가동률을 계산한 결과 모든 정박지에서 가동률이 100 %를 넘지 않는 것으로 도출되어, 추가 정박지 지정이 필요하지 않은 것으로 분석되었다. 또한 울산항의 2020년 가동률을 추정한 결과 E1정박지가 168.3 %로 가장 높았으며, E3정박지가 131.1 %, E2정박지가 118.5 %, 그리고 M정박지가 108.7 %인 것으로 계산되어, 2020년에는 정박지가 부족할 것으로 판단된다. 따라서 울산항의 항만개발에 따른 정박지 가동률을 100 % 수준으로 낮추기 위해서는 E1정박지는 11척, E2정박지는 1척, E3정박지는 2척, M정박지는 1척이 추가적으로 정박할 수 있는 수역이 필요할 것으로 분석되었다.

• Journal of Korean Dental Science
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• 제3권1호
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• pp.5-10
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• 2010

This study sought to compare the amounts of posterior anchorage loss during the en masse retraction of the upper anterior teeth between orthodontic mini-implant (OMI) and conventional anchorage reinforcement (CAR) such as headgear and/or transpalatal arch. The subjects were 52 adult female patients treated with sliding mechanics (MBT brackets, .022" slot, .019X.025" stainless steel wire, 3M-Unitek, Monrovia, CA, USA). They were allocated into Group 1 (N=24, Class I malocclusion (CI), upper and lower first premolar (UP1LP1) extraction, and CAR), Group 2 (N=15, Cl, UP1LP1 extraction and OMI), and Group 3 (N=13, Class II division 1 malocclusion, upper first and lower second premolar extraction, and OMI). Lateral cephalograms were taken before (T0) and after treatment (T1). A total of 11 anchorage variables were measured. Analysis of variance was used for statistical analysis. There was no significant difference in treatment duration and anchorage variables at T0 among the three groups. Groups 2 and 3 showed significantly larger retraction of the upper incisor edge (U1E-sag, 9.3mm:7.3mm, P<.05) and less posterior anchorage loss (U6M-sag, 0.7~0.9mm:2mm, P<.05; U6A-sag, 0.5mm:2mm, P<.01) than Group 1. The ratio of retraction amount of the upper incisor edge per 1 of anchorage loss in the upper molar made for the significant difference between Groups 1 and 2 (4.6mm:7.0mm, P<.05). Group 3 showed a relatively distal inclination of the upper molar (P<.05) and the intrusion of the upper incisor and first molar (U1E-ver, P<.05; U6F-ver, P<.05) compared to Groups 1 and 2. Although OMI could not shorten the treatment duration, it could provide better maximum posterior anchorage than CAR.

• 한국전산구조공학회논문집
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• 제31권1호
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• pp.39-46
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• 2018

본 논문에서는 상용프로그램을 이용한 유한요소해석을 통하여 포스트텐션 정착구역에서 보다 효율적인 응력분산이 가능한 비부착식 단일 강연선용 포스트텐션 정착구 형상을 개발하는 것을 목표로 하였다. 이를 위하여 정착구 형상을 구성하는 각 부분의 변수해석을 수행하였다. 본 연구에서 제안한 정착구 형상을 사용하였을 때 발생하는 최대파열응력이 기존의 정착구를 사용한 경우와 비교하여 정착구역내의 최대파열응력이 감소함을 확인하였다. 또한 본 연구의 정착구 형상을 사용하는 경우 최대파열응력 산정을 위해 AASHTO 및 기존 연구자들의 파열력 산정식을 통해 산출된 파열력을 비교 및 분석하였다. 그 결과 정착구 형상에 따른 위치계수를 수정한 파열력 산정식을 적용할 경우 정착구역이 효율적인 보강설계가 가능할 것으로 판단되었다.

• Structural Engineering and Mechanics
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• 제18권4호
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• pp.475-491
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• 2004

Anchorage devices play an important role in post-tensioned bridge structures since they must sustain heavy loads in order to permit the transfer of the prestressing force to the structure. In external prestressing, the situation is even more critical since the anchorage mechanisms, with the deviators, are the only links between the structure and the tendons throughout the service life of the structure. The behaviour of anchorage devise may be studied by using the finite element method. To do so, each component of the anchorage must be adequately represented in order to approximate the anchor mechanism as accurately as possible. In particular, the modelling of the jaw/tendon device may be carried out using the real geometry of these two components with an appropriate constitutive contact law or by replacing these components by a single equivalent. This paper presents the numerical study of a mono-strand anchorage device. The results of a comparison between two different representations of the jaw/tendon device, either as two distinct components or as a single equivalent, will be examined. In the double-component setup, the influence of the wedge configuration composing the jaw, and the influence of lubrication of the anchor, will be assessed.

• Journal of Microbiology and Biotechnology
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• 제8권5호
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• pp.461-465
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• 1998

The suspension culture of an anchorage-dependent cell line (Bok-l) from Bombina orientalis was successful in respects of cost and efficiency. The amount of cells obtained from the suspension culture was almost equivalent to that from the anchorage-dependent culture. This result shows the possibility of suspension culture for scale-up. The cells in suspension produced an antibacterial peptide as much as anchorage-dependent cells did. The cell growth ($6.0\times10^6cells/m\ell$) and viability (>80%) at 10 rpm were higher than that at 0 rpm ($1.9\times10^6cells/m\ell$, 65~80%) and 30 rpm ($1.8\times10^6cells/m\ell$ 40~76%). The size of cells became smaller at the agitation rate of 30 rpm. The antibacterial activities of cell extracts from suspension cultured cells were confirmed against gram-negative and gram-positive bacteria by the inhibition zone assay and the liquid growth inhibition assay.

• Structural Engineering and Mechanics
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• 제12권2호
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• pp.119-134
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• 2001

This paper deals with an experimental and numerical study of a mono-strand wedge anchor head mechanism. First, the experimental program is presented and monitored data such as wedge slippage, anchor deflection and strain distributions along external peripheral surfaces of the anchor head are presented and discussed. In accordance with the experimental set up, these data concern only the global behaviour of the mechanism and cannot provide valuable information such as internal stress-strains distributions, stress concentrations and percentage of yielded volume. Therefore, the second part of this paper deals with the development of an efficient numerical finite element model capable of providing mechanism of the core information. The numerical model which includes all kinematics/material/contact non-linearities is first calibrated using experimental data. Subsequently, a numerical study of the anchorage mechanism is performed and its behaviour is compared to the behaviour of a slightly geometrically modified mechanism where the external diameter has been increased by 5 mm. Finally, different topics influencing the anchorage mechanism behaviour are addressed such as lubrication and wedge shape.

• Structural Engineering and Mechanics
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• 제15권6호
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• pp.609-628
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• 2003

Mechanical anchorage devices are generally tested in the laboratory and may be analyzed using the finite element method. These devices are composed of many components interacting through diverse contact interfaces. Generally, a Coulomb friction law is sufficient to take into account friction between smooth surfaces. However, in the case of mechanical anchorages, a gripping system, named herein the wedge-tendon system, is used to anchor the prestressing tendon. The wedge inner surface is made of a series of triangular notches designed to grip the tendon. In this particular case, the Coulomb law is not adapted to simulate the contact interface. The present paper deals with a new constitutive contact/gripping law to simulate the gripping effect. A parameter identification procedure, based on experimental results as well as on a finite element/neural network approach, is presented. It is demonstrated that all parameters have been selected in a satisfactory way and that the proposed constitutive law is well adapted to simulate the wedge gripping effect taking place in a mechanical anchorage device.

• Computers and Concrete
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• 제18권5호
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• pp.951-968
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• 2016

In this study, pullout capacities of post-installed deformed bars anchored in low strength concrete using different bonding materials are investigated experimentally. The experimental study was conducted under outdoor and indoor conditions; on the beams of an actual reinforced concrete building and on concrete bases constructed at Istanbul Technical University (ITU). Ready-mixed cement based anchorage mortar with modified polymers (M1), ordinary cement with modified polymer admixture (M2), and epoxy based anchorage mortar with two components (E) were used as bonding material. Furthermore, test results are compared with the predictions of current analytical models. Findings of the study showed that properly designed cement based mortars can be efficiently used for anchoring deformed bars in low quality concrete. It is important to note that the cost of cement based mortar is much lower with respect to conventional epoxy based anchorage materials.