• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.97-98
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• 2009

In this study, tensile and shear test method for post-installed mechanical anchors embedded in concrete was proposed and the verification test was carried out to evaluate the design strength of anchor.

• Structural Engineering and Mechanics
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• v.86 no.1
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• pp.17-27
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• 2023

To investigate the mechanical behavior of the post-tensioned prestressed concrete lining (PPCL), the desilting tunnel of the Xiaolangdi Hydro Project in China is adopted as a case, and a detailed three-dimensional continuum model verified by the observation results is established for the PPCL. The radial stresses, longitudinal stresses, axial forces and bending moments of the PPCL under the completed cable tension condition (CCTC) and design water pressure condition (DWPC) are analyzed, respectively. The numerical results reveal that the PPCL concrete is significantly compressed in the circumferential direction by the prestress, while the prestress has a negligible influence on the radial stresses of the PPCL concrete. It should be noted that the concrete near the anchor slots has a complex and adverse stress state with stress concentration, longitudinal tensioning and large bending moment. In addition, a simplified shell model and a further simplified beam model which can take the influences of the prestress loss and the anchor slot into consideration are proposed for the PPCL. The results of the simplified models are in a good agreement with these of the three-dimensional continuum model, and they can be used as efficient approaches for the structural design and analysis of the PPCL.

• Smart Structures and Systems
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• v.16 no.3
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• pp.415-433
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• 2015

Tendon failures in bonded post-tensioned bridges over the last two decades have motivated ongoing investigations on various aspects of unbonded tendons and their monitoring methods. Recent research shows that change of strain distribution in anchor heads can be useful in detecting wire breakage in unbonded construction. Based on this strain variation, this paper develops a damage detection model that enables an automated tendon monitoring system to identify and locate wire breaks. The first part of this paper presents an experimental program conducted to study the strain variation in anchor heads by generating wire breaks using a mechanical device. The program comprised three sets of tests with fully populated 19-strand anchor head and evaluated the levels of strain variation with number of wire breaks in different strands. The sensitivity of strain variation with wire breaks in circumferential and radial directions of anchor head in addition to the axial direction (parallel to the strand) were investigated and the measured axial strains were found to be the most sensitive. The second part of the paper focuses on formulating the wire breakage detection framework. A finite element model of the anchorage assembly was created to demonstrate the algorithm as well as to investigate the asymmetric strain distribution observed in experimental results. In addition, as almost inevitably encountered during tendon stressing, the effects of differential wedge seating on the proposed model have been analyzed. A sensitivity analysis has been performed at the end to assess the robustness of the model with random measurement errors.

• Journal of Advanced Navigation Technology
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• v.23 no.2
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• pp.214-220
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• 2019

The calibration method of the initial value error obtained in the weight measurement through anchor bolt type strain gauge sensor is proposed. The strain gauge sensor is developed for preventing the overturning of forklift, which is the most frequent type of safety-accident in industry. It was confirmed that the initial value error is caused from the physical and mechanical error of anchor bolt, and the environmental problem. Since the elimination of these causes falls outside the realm of this research, we find out the calibrated values based on all the causes, and we adjust the initial values of analog-to-digital convertor (ADC) module consisted of strain gauge sensor block using the calibrated values. We use the linear interpolation method for our calibration. We confirm that four sensor modules have the different under 5% between the real weight and the measured value in the experiment applied with the calibration of initial values. The low correlation between the real weights and ADC values is also improved through the proposed calibration.

• The korean journal of orthodontics
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• v.49 no.3
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• pp.188-193
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• 2019

Objective: The aim of this finite element study was to clarify the mechanics of tooth movement in palatal en-masse retraction of segmented maxillary anterior teeth by using anchor screws and lever arms. Methods: A three-dimensional finite element method was used to simulate overall orthodontic tooth movements. The line of action of the force was varied by changing both the lever arm height and anchor screw position. Results: When the line of action of the force passed through the center of resistance (CR), the anterior teeth showed translation. However, when the line of action was not perpendicular to the long axis of the anterior teeth, the anterior teeth moved bodily with an unexpected intrusion even though the force was transmitted horizontally. To move the anterior teeth bodily without intrusion and extrusion, a downward force passing through the CR was necessary. When the line of action of the force passed apical to the CR, the anterior teeth tipped counterclockwise during retraction, and when the line of action of the force passed coronal to the CR, the anterior teeth tipped clockwise during retraction. Conclusions: The movement pattern of the anterior teeth changed depending on the combination of lever arm height and anchor screw position. However, this pattern may be unpredictable in clinical settings because the movement direction is not always equal to the force direction.

• Geomechanics and Engineering
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• v.29 no.6
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• pp.697-706
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• 2022

In order to explore the stable anchoring conditions of coal side under the mining disturbance of soft section coal pillar in Wangcun Coal Mine of Chenghe Mining Area, the distribution model of the anchoring support pressure at the coal pillar side was established, using the strain-softening characteristics of the coal to study the distribution law of anchoring coal side support pressure. The analytical solution for the reinforcement anchorage stress in the coal pillar side was derived with the inelastic state mechanical model. The results show that the deformation angle of the roadway side and roof increases with the roof subsidence due to the mining influence at the adjacent working face, the plastic deformation zone extends to the depth of the coal side, and the increase of anchorage stress can effectively control the roof subsidence and further deterioration of plastic zone. The roadway height and the peak support pressure have a certain influence on the anchorage stress, the required anchorage stress of the coal side rises with the roadway height and the peak support pressure. The required anchorage stress of the coal pillar side decreases as the cohesion between the coal seam and the roof and floor and the anchor length increases. Then, applied the research result to Wangcun coal mine in Chenghe mining area, the design of anchor cable reinforcement support was proposed for the section of coal pillars side that has been anchored and deformed, which achieved great results and effectively controlled the convergence and deformation of the side, providing a safety guarantee for the roadway excavation and mining.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.05a
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• pp.69-71
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• 2003

This paper introduces TRIZ. TRIZ is the theory of inventive problem solving which haws started by G.Altschuler since 1946, Russia. TRIZ is applicable for not only mechanical engineering, but also science, economic and pedagogy fields. Characteristics of some kind of softwares for TRIZ method are briefly reviewed Especially Catia with IMC TechOptimizer is studied in detail and it is expected to be applicable well for the Ocean Engineering fields, if applicably applied for IM-Principles, IM-Predictions and IM-Effects, even though it will need much efforts and time to study. As an application example of TRIZ, Self-expandable anchor which is pending for patent is presented briefly.

• KCI Concrete Journal
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• v.14 no.2
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• pp.86-91
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• 2002

This paper presents an experimental study to investigate the behavior of mechanical anchorage of reinforcing bars in concrete members. Three kinds of mechanical anchorage which are a kind of headed reinforcements are considered in this study. Total seven specimens were prepared to consider the effects of anchoring methods (Type A, Type B and Type C) and anchorage lengths of the reinforcing bars (14 $d_{b}$, 12 $d_{b}$, 9 $d_{b}$). Pullout tests conforming to ASTM were carried out to assess the effects of several variables on anchoring strength of bars. Based on the test results, it was concluded that the behavior of the specimen anchored by the mechanical anchorage with the anchor-age length of 12 $d_{b}$, is as good as, or better than that of the specimen anchored by 90-degree standard hook.rd hook.

• Tunnel and Underground Space
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• v.13 no.5
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• pp.362-372
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• 2003

Since the occurrence of Portland cement, a great number of concrete structures were constructed. But the concrete structures have their own life times, which inevitably demand repairing treatments, especially on their surface parts. Currently many various methods have been developed and are being applied fer this purpose. In this study, a newly developed method using pneumatic chipping machine and anchor pin was adopted far repair of old concrete structure and the mechanical characteristics of cementing plane between existing and new concrete were tested. Comparing the removal methods for the decrepit part of existing concrete using pneumatic chipping machine and hydraulic breaker, the peak cohesion was higher when using chipping machine at the cementing plane. On the other hand, the residual cohesion was higher for the case of breaker. Step shaped chipping on the cementing plane was effective in increasing peak cohesion, which results 14% increase in the case of 30 mm step height and 22% in 50 mm height when compared with planar chipping plane. The use of anchor pin increased the residual cohesion, which restricted shear slip on the cementing plane after peak shear stress and the tensile strength of 32% compared with that of non-anchored case. According to the combined effect of step shaped chipping of 30 mm and anchor pin with an interval of 15 cm, the peak cohesion reached up to 77% and the residual cohesion showed 180% of the ones of the fresh concrete, respectively.

• Structural Engineering and Mechanics
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• v.15 no.6
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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.