• Journal of the Korean Geosynthetics Society
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• v.16 no.3
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• pp.11-19
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• 2017

A series of pullout tests to compression type anchors is conducted. The test is carried out on a couple of steel cables installed in sandy soil with 60% of relative density. The test is performed with 6 different bonded lengths, which are 1, 2, 3, 4, 5, 6 times longer than the initial bonded length (Lc =30 mm). A numerical analysis with the same condition as the test is also performed to compare each other. Finally, those results are compared with theoretical result by Oosterbaan and Gifford (1972). The result shows that the ultimate pullout capacity appears to increase with an increase of bonded length, and that the results of test, numerical analysis and theoretical approach have a good agreement in the ultimate pullout capacity at failure.

• Journal of the Korean Geotechnical Society
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• v.17 no.3
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• pp.59-68
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• 2001

풍화토 지반에 설치된 그라운드 앵커의 하중전이 현상을 규명하기 위하여 성균관대학교 지반시험장에서 인발시험을 수행하였다. 지반과 구조물을 일체화시키는데 사용하는 앵커는 앵커체와 지반의 마찰력에 의해서 구조물을 지지하는 역할을 하며 앵커의 하중과 변형의 관계를 규명하기 위해서는 앵커의 마찰력 분포의 변화(하중전이)가 중요한 요소가 된다. 하중 재하시 앵커체에 발생하는 하중전이 분포는 앵커의 인발 지지력과 밀접한 관계가 있고 앵커체의 종류(인장형 또는 압축형), 정착장의 길이, 지반 조건 등에 따라 분포 양상이 변하기 때문에 하중전이를 이해하기 위해서는 강선과 그라우트의 하중분포 그리고 앵커 그라우트체와 지반과의 마찰력 분포를 알아야 한다. 앵커의 자유장의 강선에 작용하는 응력, 그라우트체에 작용하는 응력, 그리고 정착장 강선의 응력을 계측하여 강선과 그라우트의 정착응력 및 그라우트와 지반에서의 마찰력 분포를 구함으로써 강선-그라우트-지반의 복합적인 거동에 따른 각 하중 단계마다의 하중전이 분포를 구하였다. 또한 현장시험 결과의 신뢰성 확보를 위하여 수치해석 모델링을 통하여 해석을 수행하여 비교하였다.

• Smart Structures and Systems
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• v.19 no.3
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• pp.269-277
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• 2017

Recently, there has been significant interest in structural health monitoring for civil engineering applications. In this research, a specially designed tendon, proposed by embedding FBG sensors into the center king cable of a 7-wire strand tendon, was applied for long-term health monitoring of tensile forces on a ground anchor. To make temperature independent sensors, the effective temperature compensation of FBG sensors must be considered. The temperature sensitivity coefficient ${\beta}^{\prime}$ of the FBG sensors embedded tendon was successfully determined to be $2.0{\times}10^{-5}^{\circ}C^{-1}$ through calibrated tests in both a model rock body and a laboratory heat chamber. Furthermore, the obtained result for ${\beta}^{\prime}$ was formally verified through the ground temperature measurement test, expectedly. As a result, the ground temperature measured by a thermometer showed good agreement compared to that measured by the proposed FBG sensor, which was calibrated considering to the temperature sensitivity coefficient ${\beta}^{\prime}$. Finally, four prototype ground anchors including two tension ground anchors and two compression ground anchors made by replacing a tendon with the proposed smart tendon were installed into an actual slope at the Yeosu site. Tensile forces, after temperature compensation was taken into account using the verified temperature sensitivity coefficient ${\beta}^{\prime}$ and ground temperature obtained from the Korean Meteorological Administration (KMA) have been monitored for over one year, and the results were very consistent to those measured from the load cell, interestingly.

• Steel and Composite Structures
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• v.29 no.2
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• pp.257-272
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• 2018

The research of shear connectors composed from mechanical couplers with rebar anchors, embedded in concrete, and steel bolts, as a mean of shear transfer in composite connections is presented in the paper. Specific issues related to this type of connections are local concrete pressure in the connector vicinity as well as the shear flow along the connector axis. The experimental research included 18 specimens, arranged in 5 series. Nonlinear numerical analyses using Abaqus software was conducted on corresponding FE models. Different failure modes were analysed, with emphasis on concrete edge failure and bolt shear failure. The influence of key parameters on the behaviour of shear connector was examined: (1) concrete compression strength, (2) bolt tensile strength and diameter and (3) concrete edge distance. It is concluded that bolted shear connectors with mechanical couplers have sufficient capacity to be used as shear connectors in composite structures and that their behaviour is similar to the behaviour of post installed anchors as well as other types of connectors anchored without the head.

• The Academic Congress of Korean Shoulder and Elbow Society
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• 2008.03a
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• pp.178-178
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• 2008

In order to improve static stability and healing of reattached labrum, we combined the advantages of suture bridge and transosseous technique. Using the conventional 3 portal for anterior instability, check stability of bony Bankart and preparation of glenoid bed in 3 way including removal, reshaping or mobilization of bony fragment. Two anchors were inserted to the superior and inferior portion and medial edge of bony Bankart lesion. It usually corresponded to the area of IGHL. Medial mattress sutures were applied around IGHL complex to get enough depth of glenoid coverage using suture hook. Make 3.5mm pushlock anchor hole to the articular edge of glenoid cartilage. Proximal suture bridge was applied at first and then distal suture bridge was inserted to mobilize the labrum in proximal direction. These construction can provide more stable labral repair with wide contact and compression in case of deficient bony stability. It not only avoids technical disadvantage of point contact with anchor fixation, but also decreasing gap formation through cross compression of labrum that couldn't gain even with the transosseous fixation which affords linear compression effect. Additional bony stability could be gained if the the bony fragment was mobilized to the glenoid margin with potential healing bed or reshaped for the good contact with reattached labrum.

• Journal of the Korean Arthroscopy Society
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• v.13 no.2
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• pp.179-182
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• 2009

Purpose: Point fixation at the margin of the glenoid is a limitation of conventional arthroscopic stabilization using suture anchors, and does not afford sufficient footprint healing, especially in glenoid bone deficiency. So, we introduce an arthroscopic suture bridge transosseous-equivalent technique for bony Bankart lesions to avoid the technical disadvantage of point contact with anchor fixation and to improve mechanical stability through cross compression of the labrum. Surgical approach: The technique was adapted from the transosseous-equivalent rotator cuff repair technique using suture bridges, which improved the pressurized contact area and mean pressure between the tendon and footprint. After preparation of the glenoid bed by removal, reshaping, or mobilization of the bony lesion, two anchors (3.0 mm Biofastak, $Arthrex^{(R)}$, Naples, FL) were inserted into the superior and inferior portion of the bony Bankart lesion. Using a suture hook, medial mattress sutures were applied around the capsulolabral portion of the IGHL complex to obtain sufficient depth of glenoid coverage. A 3.5 mm pushloc anchor ($Arthrex^{(R)}$, Naples, FL) hole was made in the articular edge of the anterior glenoid rim. distal, suture bridge was applied, and proximal was inserted to mobilize the labrum in the proximal direction. This avoided the technical disadvantage of point contact with anchor fixation and decreased the level of gap formation through cross-compression of the labrum.

• Journal of the Korea Concrete Institute
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• v.21 no.3
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• pp.291-302
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• 2009

A compression lap splice can be calculated longer than a tension lap splice in high strength concrete according to current design codes. New criteria for the compression lap splice including the effects of concrete strength are required for practical purpose of ultra-high strength concrete. Characteristics of compression lap splice have been extensively investigated and main parameters are derived. In addition, an experimental study has been conducted with column specimens in concrete strength of 40 and 60 MPa. The strength of the compression lap splice consists of bond and end bearing and two contributors are combined. Therefore, combined action of bond and end bearing should be assessed. Compared with tension splices, concrete strength significantly affects the strength of compression splices due to short splice length and existence of end bearing. Test results show that the splice strength can be evaluated to be proportional to square root of compressive strength of concrete. The stress states of concrete surrounding spliced bars govern the strengths of bond and end bearing. Because the axial stress of the concrete is relatively high, the splice strength is not dependent on clear spacing. End bearing strength is not affected by splice length and clear spacing and is expressed with a function of the square root of concrete strength. The failure mode of specimens is similar to side-face blowout of pullout test of anchors and the strength of end bearing can be evaluated using the equation of side-face blowout strength. Because the stresses developed by bond in compression splices are nearly identical to those in tension splices, strength increment of compression splices is attributed to end bearing only.

• 기술발표회
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• s.2006
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• pp.66-72
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• 2006

The ground anchoring has been utilized over 40 years. It is growing the application of the removal ground anchor with tension force for holding earth retaining constructions in the city. It transmits tension stress of prestressed steel wire through grouting to fixed the ground that is of great advantage adjacent ground stability. Nowadays, we can find the compression dispersion anchor on many site. But, it has some problems in behavior of anchors because of impossible to tense p.c strand uniformly under the existing equipment due to different length of p c strand. Hence, motive of this research was to study the application of the newly developed tension system, that analyze and compare with the current anchoring method build on the data of in-site test and laboratory test. As a result, in case of auto back tension system, it became clear that tension pressure was equally distributed among the steal wires but the existing tension system showed sign of instability by indicating stress deflection of about 30% compare with design load. This can cause an ultimate failure of the concentrated p.c strand and a shear failure of ground.

• The Academic Congress of Korean Shoulder and Elbow Society
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• 2009.03a
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• pp.162-162
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• 2009

After preparation of the bone bed, two doubly loaded suture anchors with suture eyelets are inserted at the articular margin of the greater tuberosity. A retrograde suture-passing instrument penetrates the rotator cuff to retrieve the sutures through the modiWed Neviaser or subclavian portal. An ipsilateral pair of suture eyelets in the suture anchor is passed through the margins of the rotator cuff tear. The blue suture of the second and third pair is pulled out of the lateral cannula, and the threaded blue suture of the third pair in the needle is passed through the blue suture of the second pair. After retrieving the blue suture of the firrst pair through the anterior portal, it is pulled out to pass the blue suture of the third pair through the eyelet of the anteromedial anchor. The blue suture is linked between two anchors. The medial row of suture bridge is repaired with a sliding knot, and the sutures are not cut. Once the rotator cuff repair using the suture-bridge technique has been performed, the two blue strands in the anterior portal are tied. We describe our technique that possesses the advantages of both the double-pulley and suturebridge techniques, which improves the pressurized contact area and maximizes compression along the medial row.

• Journal of Korean Society of Steel Construction
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• v.20 no.1
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• pp.1-8
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• 2008

This research carried out to optimize crossbeams and stringers of steel box girder bridges, which are parts of floor system and support loading from the bridge deck. In the current design practice, the crossbeam is densely deployed with a spacing of 6 meters, and the stringer is placed between the crossbeams. The crossbeams and stringer are connected to the deck through slab anchors but the allowable stress of the compression flange is determined by the lateral-torsional buckling. To increase economic efficiency of the steel box girder bridges. the increased spacing of the crossbeam was studied. The study shows that the spacing can be increased up to 10 meters. However, higher strength steel plates are necessary. Shear studs rather than slab anchors are also recommended to prevent lateral-torsional buckling strength of the crossbeams and stringer.