• KCI Concrete Journal
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• 제14권2호
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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.

• 도시과학
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• 제7권2호
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• pp.21-27
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• 2018

With the increase of the skyscraper center, the development of large-diameter and high-strength reinforcing bars is being carried out to solve the dense reinforcement. In case of the steel reinforced concrete with a small cross section such as beam-column joints, the development length becomes short when straight bars are used. Therefore, it is possible to solve the problem that the development length becomes short by using the bearing strength of the hooked bar and headed bar. In this study, the exterior beam-column joint test of SD700 hooked bar and headed bar with anchorage length of 20db was conducted to extend the development length limitation of hooked bar and headed bar. As a result of the evaluation of the anchorage strength using the design equation by KCI, the average of the [measured value]/[predicted value] ratio was 1.31 for the hooked reinforcing bars. In the case of headed bars, the average of the [measured value]/[predicted value] ratio was 1.12. In addition, in order to compare the anchorage performance of the hooked bar and the headed bar, the measured values were divided by the square root of the compressive strength of the concrete to compare the anchorage strength. Under the same conditions, the anchorage strength of headed bars was 8.5% higher than the hooked bars.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.405-410
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• 2002

This paper deals with the flexural behavior of RC hems strengthened with CFRP plate and the estimation on anchorage length of CFRP Plate. Experimental variables included concrete strength, reinforcement ratio, cover thickness of concrete and length ratio of CFRP plate for a pure span. A failure load, failure mode, deflection and strain response at different distances from a cut-off point of CFRP plate were observed and anchorage length was determined through strain distribution of CFRP plate. Herein, anchorage length is defined the length between CFRP plate end and the beginning point of full composite behavior. Also, the anchorage length observed from the experiment was compared with Nguyen's equation and BS specification.

• Architectural research
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• 제2권1호
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• pp.55-60
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• 2000

Recently, there is a great demand for precast reinforced concrete (RC) construction methods on the purpose of simplicity in construction. Nishimatsu Construction Company has developed a construction method with precast reinforced concrete members in medium-rise building. In this construction method, how to joint precast members, especially the anchorage of the main bar of beam, is important problem. In this study, the structural performance of exterior joints with precast members was investigated. The parameters of the test specimens are anchorage type of the main bar of beam (U-shape anchorage or anchorage plate) and the ratio of the column axial force to the column strength. Specimens J-3 and J-4 used U-shape anchorage and the ratio of the column axial force of specimen J-4 was higher. On the other hand, specimens J-5 and J-6 used anchorage plate, and the anchorage lengths are 15d and 18d, respectively. Experimental results are summarized as follows; 1) For the joints with beam flexural failure mode, it was found that the maximum strength of specimen with anchorage plate is equal to or larger than that of specimen with conventional U-shaped anchorage if the anchorage length of more than 15d would be ensured, 2) Each specimen shows stable hysteretic curves and there were no notable effects on the hysteretic characteristics and the maximum strength caused by the anchorage method of beam main bar and the difference of column axial stress level.

• Journal of the Korean Wood Science and Technology
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• 제40권5호
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• pp.327-334
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• 2012

Wood and concrete show significantly different physical properties, and it need to be firstly understood for using wood-concrete composite. This study is performed for compensating this and effective hybridization of wood and concrete. This research in planned for wood-concrete composite after previous research which deals the shear performance with different anchorage length of steel rebar in wood. Yield mode and reference design value (Z) were derived using EYM (European Yield Model). And the yield mode changed before and after anchorage length of 10~15 mm - $I_s$ mode to IV mode. There was not increasing tendency of shear performance with increased anchorage length for over 20 mm of anchorage in concrete. And wood composite shows 65% and 93% on initial stiffness and yield load respectively compared with the wood-concrete composite. Wood-concrete composite showed brittle failure after yield point while wood-to-wood composite showed ductile failure.

• Geomechanics and Engineering
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• 제11권6호
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• pp.787-803
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• 2016

DDARF (Discontinuous Deformation Analysis for Rock Failure) is a numerical algorithm for simulating jointed rock masses' discontinuous deformation. While its reinforcement simulation is only limited to end-anchorage bolt, which is assumed to be a linear spring simply. Here, several new reinforcement modes in DDARF are proposed, including lining reinforcement, full-length anchorage bolt and equivalent reinforcement. In the numerical simulation, lining part is assigned higher mechanical strength than surrounding rock masses, it may include multiple virtual joints or not, depending on projects. There must be no embedding or stretching between lining blocks and surrounding blocks. To realize simulation of the full-length anchorage bolt, at every discontinuity passed through the bolt, a set of normal and tangential spring needs to be added along the bolt's axial and tangential direction. Thus, bolt's axial force, shearing force and full-length anchorage effect are all realized synchronously. And, failure criterions of anchorage effect are established for different failure modes. In the meantime, from the perspective of improving surrounding rock masses' overall strength, a new equivalent and tentative simulation method is proposed, it can save calculation storage and improve efficiency. Along the text, simulation algorithms and applications of these new reinforcement modes in DDARF are given.

• 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.

• 콘크리트학회논문집
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• 제14권5호
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• pp.645-652
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• 2002

본 논문은 탄소 FRP 판을 이용한 철근 콘크리트 보의 휨 보강효과와 거동에 대한 연구이다. 본 연구에서의 실험인자로는 휨보강 탄소 FRP 판의 부착길이와 탄소 FRP 쉬트의 복부정착 길이이다. 시험보는 탄소 FRP 판으로 인장면에 부착하여 휨 보강하고 FRP 판을 탄소 FRP 쉬트로 복부에 정착하였다. 일반적으로 복부정착이 없는 휨 보강된 보들의 파괴형태는 횡방향 주철 근을 따라 발생한 콘크리트 덮개 박리파괴를 나타내었다. 반면, 탄소 FRP 쉬트로 복부 정착된 휨 보강 보들은 CFRP 파단파괴 후 콘크리트 경계면 전단 박리파괴를 나타내었다. 보강된 보들의 극한하중과 극한처짐은 FRP 판의 휨 부착길이의 증가에 따라 증가하였다. 또한, 휨 보강된 보들은 FRP 쉬트의 복부정착 길이의 증가에 따라 극한하중과 극한처짐 값이 증가하였다. 특히, 복부 정착한 보들은 최대 극한하중에 도달한 후에도 상당한 극한하중 지지능력을 상당한 극한 처짐 시까지 유지하였다. 시험보의 길이에 걸친 FRP 판의 변형률 분포는 휨 모멘트도의 모양과 거의 유사하여 전단지간에서 일정한 전단응력 분포를 가정할 수 있었다. 전지간을 휨 보강한 보에 있어서는 콘크리트와 FRP 쉬트에 의한 경계면에서의 극한전단 저항강도는 복부정착 길이가 늘어남에 따라 증가하였다. 전단 저항강도 중에서 본 실험에서 사용한 복부 정착 FRP 쉬트도 일부의 전단 저항강도를 부담하였다.

• Geomechanics and Engineering
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• 제36권1호
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• pp.71-81
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• 2024

This study analyzes the pull-out behavior of tunnel-type anchorage under various joint conditions, including joint direction, spacing, and position, using a finite element analysis. The validity of the numerical model was evaluated by comparing the results with a small-scaled model test, and the results of the numerical analysis and the small-scaled model test agree very well. The parametric study evaluated the quantitative effects of each influencing factor, such as joint direction, spacing, and position, on the behavior of tunnel-type anchorage using pull-out resistance-displacement curves. The study found that joint direction had a significant effect on the behavior of tunnel-type anchorage, and the pull-out resistance decreased as the displacement level increased from 0.002L to 0.006L (L: anchorage length). It was confirmed that the reduction in pull-out resistance increased as the number of joints in contact with the anchorage body increased and the spacing between the joints decreased. The pull-out behavior of tunnel-type anchorage was thus shown to be significantly influenced by the position and spacing of the rock joints. In addition, it is found that the number of joints through which the anchorage passes, the wider the area where the plastic point occurs, which leads to a decrease in the resistance of the anchorage.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.629-640
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• 2008

South anchorage(AN1, Myodo side) of supension bridge between Myodo and Gwangyang is designed as rock anchorage with 36m anchor length using the resistance of rock mass in Myodo. Checking the overall stability of the anchorage, we considered rock joints, bedding planes, fault zones and condition of rock structure in situ by analysis results for photo-lineaments, aerial photograph interpretation and drill-hole logs are considered. This anchorage consists of an access shaft, adit, and the upper and lower concrete bearing plate to introduce pre-stressing force into rock mass.