• Journal of the Korean Geotechnical Society
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• v.37 no.2
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• pp.33-48
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• 2021

The rock anchorage of a suspension bridge is an outstanding anchorage type from environmental and economical perspective, although it should be applied when the bearing foundation is fresh enough to resist large cable loads. In practice, geotechnical engineers have encountered difficulties in designing the anchorage structure due to the fact that the physical behaviors of rocks against cable loads have not yet been fully proved and its design method was not established yet. In this study, model tests and numerical studies were performed to evaluate the behavior of the rock anchorage system planned under hard rock layers in domestic islands, and results suggest that the shape of asymmetric rock wedges can resist the tension loads with self weight and shear resistance. Additionally, real scale trial tests were carried out to verify the accuracy of an inclined drilling penetrating hard rock layers to install tendon to the bearing plate.

• Journal of the Korea Institute of Building Construction
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• v.5 no.4 s.18
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• pp.139-144
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• 2005

A ground anchor system is used as a load carrying element in soil work. The conventional systems with ground anthers bring about the anchorage loss of wedges when anchors are installed for the support of soil structures. Hence we developed the new type of anchor system using both the spacing apparatus and spring (length 60mm, diameter 6mm). In this system, we tan directly check the condition of wedges and PS strands and modify the problems with the slip and anchorage of wedges under construction. For demonstrating the superiority of this system, we carried out a series of the laboratory test. Consequently, we can obtain satisfactory result (18.99$\%$ reduction to the loss of conventional systems). Moreover, the replacement of wedges is easy and simple when retensioning of strands.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.59-62
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• 2005

Seven columns laterally reinforced with either mechanically anchored crossties or conventional crossties under cyclic loading are tested. 4 columns are specimens for flexural strength and 3 columns are for shear strength. Main variable is anchorage types of crossties. Conventional hooks, 180$^{\circ}$ standard hook-mechanical anchorage and all mechanical anchorage type are used. The specimens are tested under 10$\%$ axial load of nominal axial capacity of the columns combined with increasing lateral load. From the flexure test, it is found that columns with mechanical anchorages exhibit superior performance in terms of ductility and energy dissipation. The crossties with mechanical anchorages reduce buckling length of longitudinal rebar. From the shear test, it is found that. 3 specimens exhibit almost the same strength, displacement, and shear failure mode at ductility factor =2.

• Explosives and Blasting
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• v.37 no.4
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• pp.26-35
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• 2019

In designing a gravity-type anchorage of earth-anchored suspension bridge, the contact friction between a blasted rock mass and the concrete anchorage plays a key role in the stability of the entire anchorage. Therefore, it is vital to understand the shear behavior of the interface between the blasted rock mass and concrete. In this study, a portable 3D LiDAR scanner was utilized to scan the blasted bottom surfaces, and rock surface roughness was quantitatively analyzed from the scanned profiles to apply to 3D FEM modelling. In addition, based on the 3D FEM model, a three-dimensional dynamic fracture process analysis (DFPA-3D) technique was applied to study on the shear behavior of the interface between blasted rock and concrete through direct shear tests, which was analyzed under constant normal load (CNL). The effects of normal stress and the joint roughness on shear failure behavior are also analyzed.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.6
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• pp.123-135
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• 2006

Most of all, large spatial span structures are the symbol of cities but have to get to supply the purpose of structure simultaneously, therefore their foundations are designed to get rolls of structure support, structure shape maintenance or overturn prevention, buoyancy resistance, etc. Accordingly various type foundations have been introduced, and after anchorage power is introduced for double structures shape maintenance and overturn prevention, change of anchorage power checked in the construction process is reviewed, comparing of playground case. Case1 anchors for the control of horizontal power worked outside hemisphere type roof, Case2 anchors for the overturn prevention of cantilever roof examined in this example. The examination has been executed by the analysis of anchorage power introduction process, related test results and anchorage power monitoring results for 2 examples.

• The Journal of Korean Academy of Prosthodontics
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• v.45 no.4
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• pp.492-505
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• 2007

Statement of problem: An orthodontic miniscrew implant has been used as a skeletal anchorage for orthodontic treatment. However, any relation among the influence of the cortical bone, morphologic differences of orthodontic miniscrew implants and new bone formation hasn't been made clear yet. Purpose: The purpose of this study was to evaluate whether the orthodontic miniscrew implant could work as an intraoral skeletal anchorage immediately and stably for orthodontic treatment after insertion of it. Material and methods: Two types of orthodontic miniscrew implants were used in this experiment; tapered type and straight type. One hundred and sixty eight orthodontic miniscrew implants were inserted into the tibiae of 21 rabbits and sacrificed on 3, 7, 11, 14, 21 and 28days later after insertion of them to study removal torque values and histologic and histomorphometric analyses. Results: The results were as follows. 1. The removal torque values of the tapered type were higher than those of the straight type in all groups(p<0.05). 2. There wasn't any distinguishing differences between the tapered type and the straight type about the new bone formation percentage. 3. The removal torque values for both the tapered type and the straight type were gradually decreased at early stages of the test but started to increase at the 7 days group of the straight type and the 11 days group of the tapered type. 4. New bone formation percentage was increased gradually for both the tapered and the straight types as time passed(p<0.05). 5. It was found that the tapered type showed lower values in the cortical bone about both the maximum equilibratory stress distribution and the maximum principal stress distribution than the straight type in linear finite elements analysis. Conclusion: According to the research, the removal torque values were decreased at 7 days group of the tapered type and 11 days group of the straight type after the insertion of the orthodontic miniscrew implants in tibiae of rabbits. Considering the human bone activity, it is better to apply the orthodontic force $3{\sim}4$ weeks later than to apply it immediately after the insertion of orthodontic miniscrew implants. Considering that general orthodontic force is about $250{\sim}500$ grams, the tapered type can be worked as a stable skeletal anchor age in an orthodontic treatment even if the orthodontic force is applied on it immediately after the insertion of it.

• The magazine of the Korean Society for Advanced Composite Structures
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• v.1 no.2
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• pp.23-34
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• 2010

• Geomechanics and Engineering
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• v.12 no.1
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• pp.139-160
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• 2017

The bearing mechanism of tunnel-type anchorage (TTA) for suspension bridges is studied. Model tests are conducted using different shapes of plug bodies, which are circular column shape and circular truncated cone shape. The results show that the plug body of the latter shape possesses much larger bearing capacity, namely 4.48 times at elastic deformation stage and 4.54 times at failure stage compared to the former shape. Numerical simulation is then conducted to understand the mechanical and structural responses of plug body and surrounding rock mass. The mechanical parameters of the surrounding rock mass are firstly back-analyzed based on the monitoring data. The calculation laws of deformation and equivalent plastic strain show that the numerical simulation results are rational and provide subsequent mechanism analysis with an established basis. Afterwards, the bearing mechanism of TTA is studied. It is concluded that the plug body of circular truncated cone shape is able to take advantage of the material strength of the surrounding rock mass, which greatly enhances its bearing capacity. The ultimate bearing capacity of TTA, therefore, is concluded to be determined by the material strength of surrounding rock mass. Finally, recommendations for TTA design are proposed and discussed.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.6
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• pp.147-154
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• 2008

Experimental study has been performed in order to investigate the behavior of RC beams strengthened with externally unbonded post-tensioned CFRP (Carbon Fiber Reinforced Polymer) strips using embedded or stud-type plate anchorages. Total 10 small-scaled specimens were manufactured with the different post-tensioning level and types of mechanical anchorage as a main test parameter. A control specimen and specimens with simply bonded CFRP strips were included to compare the structural performances of each system. From the test results, it was observed that the specimens strengthened with simply bonded CFRP strips showed debonding failure below 50% of CFRP tensile strength due to premature debonding. On the other hand, all the specimens strengthened with post- tensioned unbonded CFRP strips reached the rupture strength of the CFRP strip. Also, it was observed that the specimens with stud-type anchorage have equivalent strengthening performance compared with embedded-type anchorage.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.125-128
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• 2008

In the recent construction industry, external tendon method has been widely used for strengthening and repair of civil structures. This paper presents the strengthening effectiveness and application of the proposed external tendons using lifting hole anchorage system. Based on the experimental results of the previous external tendons using lifting hole anchorage systems, two types of modified systems were proposed. In order to verify the strengthening effectiveness of the two systems, six beams were built and a series of experiments was carried out. To compare and analyze the behaviors of the proposed systems, deflections and strains were measured. Additionally, yield load, ultimate load and failure modes were compared and analyzed.