• Geomechanics and Engineering
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• 제28권2호
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• pp.197-207
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• 2022

The seismic holding behaviors of plate anchor embedded into submerged coarse-grained soils were investigated considering different anchor inclinations. The limit equilibrium method and the Pseudo-Dynamic Approach (PDA) were employed to calculate the inertia force of the soils within the failure rupture. In addition, assuming the permeability of coarse-grained soils was sufficiently large, the coefficient of hydrodynamic force applied on the inclined plate anchor is obtained through adopting the exact potential flow theory. Therefore, the seismic holding resistance was calculated as the combination of the inertia force and the hydrodynamic force within the failure rupture. The failure rupture can be developed due to the uplift loads, which was assumed to be an arc of a circle perpendicular to the anchor and inclines at (π/4 - φ/2). Then, the derived analytical solutions were evaluated by comparing the static breakout factor N_γ to the published experimental and analytical results. The influences of soil and wave properties on the plate anchor holding behavior are reported. Finally, the dynamic anchor holding coefficients N_γd, were reported to illustrate the anchor holding behaviors. Results show that the soil accelerations in x and z directions were both nonlinear. The amplifications of soil accelerations were more severe at lower normalized frequencies (ωH/V) compared to higher normalized frequencies. The coefficient of hydrodynamic force, C, of the plate anchor was found to be almost constant with anchor inclinations. Finally, the seismic anchor holding coefficient oscillated with the oscillation of the inertia force on the plate anchor.

• Steel and Composite Structures
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• 제21권2호
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• pp.357-371
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• 2016

Column base connections are critical components in steel structures because they transfer axial forces, shear forces and moments to the foundation. Exposed column bases are quite commonly used in low- to medium-rise buildings. To investigate shear transfer in exposed column base plates, four large scale specimens were subjected to a combination of axial load (compression or tension) and lateral shear deformations. The main parameters examined experimentally include the number of anchor rod, arrangement of anchor rod, type of lateral loading, and axial force ratio. It is observed that the shear resisting mechanism of exposed column base changed as the axial force changed. When the axial force is in compression, the resisting mechanism is rotation type, and the shear force will be resisted by friction force between base plate and mortar layer. The specimens could sustain inelastic deformation with minimal strength deterioration up to column rotation angle of 3%. The moment resistance and energy dissipation will be increased as the number of anchor rods increased. Moreover, moment resistance could be further increased if the anchor rods were arranged in details. When the axial force is in tension, the resisting mechanism is slip type, and the shear force will be resisted by the anchor rods. And the shear resistance was reduced significantly when the axial force was changed from compression to tension. The test results indicated that the current design approach could estimate the moment resistance within reasonable acceptance, but overestimate the shear resistance of exposed column base.

• 비파괴검사학회지
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• 제31권1호
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• pp.11-23
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• 2011

In this study, a finite element(FE) analysis on electro-mechanical impedance response of cable-anchor connection interface under various anchor force is presented. In order to achieve the objective, the following approaches are implemented. Firstly, an interface washer coupled with piezoelectric(PZT) material is designed for monitoring cable-force loss. The interface washer is a small aluminum plate on which a PZT patch is surface-bonded. Cable-force loss could be monitored by installing the interface washer between the anchor plate and the anchorage of cable-anchor connection and examining the changes of impedance of the interface washer. Secondly, a FE model for cable-anchor connection is established to examine the effect of cable-force on impedance response of interface washer. Also, the effects of geometrical and material properties of the interface washer on impedance responses under various cable-forces are investigated. Finally, validation of the FE analysis is experimentally evaluated by a lab-scale cable-anchor connection.

• Geomechanics and Engineering
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• 제22권3호
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• pp.265-275
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• 2020

As a flexible supporting structure, the anchoring frame structure is widely adopted to support multistage slopes in high earthquake-intensity area for its effectiveness and practicality. The previous study indicates that the anchor of anchoring frame structure is the most likely to be damaged during earthquakes. It is crucial to determine the pull-out capacity of anchor against seismic force for the seismic design of anchoring frame structure. In this study, an analytical model of a three-stage slope supported by anchoring frame structure is established, and the upper bound method of limit analysis is applied to deduce the seismic anchor force of anchoring frame structure. The pull-out capacity of anchor against seismic force of anchoring frame structure at each stage is obtained by computer programming. The proposed method is proved to be reasonable and effective compared with the existing published solution. Besides, the influence of main parameters on the pull-out capacity of anchor against seismic force is analyzed to provide some recommendations for the seismic design of anchoring frame structure.

• 지질공학
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• 제30권4호
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• pp.673-682
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• 2020

비탈면의 안정성 측면에서 파괴형태에 따라 예상 파괴면에서의 지반 전단력과 앵커보강에 의한 저항력은 중요한 요소로 작용할 수 있다. 또한, 앵커가 보강된 비탈면에서는 지압판이 설치된 지반의 풍화, 침하 및 불완전하게 방청 처리된 강연선의 부식 등으로 인하여 앵커축력이 변할 수 있다. 그러나 앵커 축력의 변화로 인해 국부적으로 앵커의 저항력을 상실한 경우에는 앵커가 저항력을 발휘하지 못하게 되어 주변 앵커로 외력이 전가되는 경향이 있으며, 이에 따라 주변앵커의 긴장력을 증가시키게 된다. 이로 인해 전체 비탈면의 안정성에 문제가 발생하게 되므로 주의가 요구된다. 따라서 본 연구에서는 비탈면에 설치되어 있는 앵커의 긴장력 변화경향을 모니터링하고 이를 고려한 비탈면 전체의 외적 안정성을 유추하는 방법을 제안하고자 하였다.

• 한국지반공학회논문집
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• 제34권4호
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• pp.13-25
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• 2018

앵커가 보강된 비탈면에 활동이 발생한 경우에는 활동면을 따라 전단면에 전단응력과 휨 응력이 작용하게 되고, 전단변형의 증가는 앵커의 긴장력 변화를 야기한다. 본 연구에서는 전단에 따른 앵커의 긴장력 변화를 확인하기 위해 앵커의 수직방향으로 전단변형을 유발하여 앵커의 긴장력을 측정하는 방법으로 대형 직접전단시험기를 통해 전단시험을 수행하였다. 전단시험은 앵커 설치 유무, 정착부에서 전단면까지의 이격거리(1D, 2D, 4D) 및 측압(0.1MPa, 0.2MPa)을 변수로 총 8가지 조건에 대해 시험을 실시하였다. 전단시험 결과, 이격거리와 주변지반의 측압은 앵커가 설치된 모형 지반의 전단력 및 앵커의 긴장력에 영향을 미치는 것으로 나타났으며, 전단력 변화는 앵커 두부 및 선단부의 축력변화와 관련이 있음을 규명하였다. 따라서 앵커 두부에서의 긴장력 변화 경향을 분석함으로써, 간접적으로 앵커 정착부에서의 전단변형에 따른 거동을 예측할 수 있음을 확인하였다.

• 한국해양공학회지
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• 제18권1호
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• pp.47-52
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• 2004

Greater holding force of an anchor is required for maintaining the position of a larger floating structure. According to the series of model tests of pile anchors with movable fluke, the square type pile anchor, with fluke, showed more than 6 times of the uplift pulling force, compared to the same type pile anchor, without fluke. This uplift force is 100 times its weight. When the water depth is more than 40m, It is difficult to install the pile anchor. For a convenient installation method, a type of manipulator is proposed for the separation of a weight and buoyancy controller, using TRIZ.

• 수산해양기술연구
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• 제32권2호
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• pp.132-147
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• 1996

The optimal design of floating type fisheries facilities in the open sea is demanded considering with the severe hydrodynamic forces on floating body, mooring tension and holding force of anchor. For conserving the facilities in most effective state, design and selection of anchor system is one of the most important fundamental subject. To enhance the design procedure of anchor system the holding forces of anchor are investigated by the hydraulic model test and are compared with the typical conventional results for various anchors. Applicability of previous estimation methods of holding force are checked and holding mechanism of anchor is discussed. Using the results a new computational concept of holding force is suggested considering mainly the effects of passive soil pressure (resistance), steady soil pressure, and surface friction etc. The new estimation method is proved as a feasible one by comparing the results of hydraulic model experiments. Applicability of various anchors to the anchor system on open sea fisheries structures is comprehensively reviewed using the present model tests and previous study results in the viewpoint of economy, construction and stability etc. Using the results, fundamental anchoring system design procedures are suggested to apply huge marine ranching complex with increase of the holding capacity of anchor under the optimum cost.

• 대한조선학회논문집
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• 제48권2호
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• pp.183-187
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• 2011

As larger the commercial vessel is, and rougher the marine environment becomes nowadays, drag embedment type anchor (DEA) of more stable performance and higher holding power is requested to be applied on the vessel. But, the performance of DEA has not become well known to academy and industries so far, that the basic study of DEA performance and holding force for the development of new DEA of higher performance is insufficient that required. In this paper, three types of same holding category DEA model (HALL, AC-14, POOL-N, scale 1/10), which are generally applied on the commercial vessel nowadays, were tested by being horizontally dragged on the test tank, on which sand was being floored with sufficient depth, and measured the holding force of each anchor simultaneously using load cell and D/A converter. With the test results, the embedding motion was analyzed to have three different stages and the holding force of each anchor was analyzed with respect to the anchor geometry, such as shape and weight of each type of anchors, and final embedding depth.

• Smart Structures and Systems
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• 제7권4호
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• pp.303-317
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• 2011

A specially designed tendon, which is proposed by embedding an FBG sensor into the center king cable of a 7-wire strand tendon, was applied to monitor the prestress force and load transfer of ground anchor. A series of tensile tests and a model pullout test were performed to verify the feasibility of the proposed smart tendon as a measuring sensor of tension force and load transfer along the tendon. The smart tendon has proven to be very effective for monitoring prestress force and load transfer by measuring the strain change of the tendon at the free part and the fixed part of ground anchor, respectively. Two 11.5 m long proto-type ground anchors were made simply by replacing a tendon with the proposed smart tendon and prestress forces of each anchor were monitored during the loading-unloading step using both FBG sensor embedded in the smart tendon and the conventional load cell. By comparing the prestress forces measured by the smart tendon and load cell, it was found that the prestress force monitored from the FBG sensor located at the free part is comparable to that measured from the conventional load cell. Furthermore, the load transfer of prestressing force at the tendon-grout interface was clearly measured from the FBGs distributed along the fixed part. From these pullout tests, the proposed smart tendon is not only expected to be an alternative monitoring tool for measuring prestress force from the introducing stage to the long-term period for health monitoring of the ground anchor but also can be used to improve design practice through determining the economic fixed length by practically measuring the load transfer depth.