• 한국지진공학회논문집
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• 제20권6호
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• pp.351-360
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• 2016

In regions of low-to-moderate seismicity, various types of lap splices are used for longitudinal reinforcement of columns at the plastic hinge zones. The seismic performance of such lap spliced columns, such as strength, deformation capacity, and energy dissipation, is affected by material strengths, longitudinal re-bar size, confinement of hoops, lap splice location, and lap splice length. In the present study, cyclic loading tests were performed for columns using three types of lap splices (bottom offset bar splice, top offset bar splice, and splice without offset bend). Lap splice length($40d_b$ and $50d_b$) was also considered as test parameters. Ties with 90-degree end hooks were provided in the lap splice length. The test results showed that strength, deformation capacity, and energy dissipation of columns significantly differed depending on the details and the length of lap splices. The bottom offset bar splice showed high ductility and energy dissipation but low strength; on the other hand, the top offset bar splice and the splice without offset bend showed high strength but moderate ductility and energy dissipation.

• 한국안전학회지
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• 제25권6호
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• pp.70-74
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• 2010

For each strand of wirerope sling, the international standards, ISO-8794, EN-13414 specify that the splice shall have five series of load carrying tucks. At least three of the load carrying tucks shall be made with the whole strand. And, the breaking force of the splice shall not be less than 70% or 80% of that of rope. But, There are no prescriptions for splicing types against different efficiency of each splicing type being used many workplace. In this study, analysis the work limit load efficiency according to variation of number of tucks and splicing types by experimental method As a result, the number of tucks 3+2 had the highest breaking efficiency.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2000년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Spring
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• pp.335-340
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• 2000

The influence of lap splice of longitudinal bars in the plastic hinge zone on the nonlinear behavior characteristics of RC piers has been investigated through the scale model tests. The seismic performance of bridge piers with lap splice is found to be insufficient due to the premature bond failure. On the other hand it is confirmed that the preventing lap splice in the plastic hinge zone enhance the seismic performance considerably even without the seismic details of transverse reinforcements. Bases on these experimental results new seismic detailing concept appropriate to moderate seismicity region has been proposed.

• Earthquakes and Structures
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• 제14권5호
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• pp.379-388
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• 2018

This study aims to identify the effect of both longitudinal reinforcement details and damage level on making a decision of repairing pre-damaged bridge columns using basalt fiber reinforced polymer (BFRP) jackets. Two RC bridge columns with improper details of the longitudinal and/or transverse reinforcement were tested under the effect of a constant axial load and increasing lateral cyclic loading. Test results showed that the lap-splice column exhibited an inferior performance where it showed rapid degradation of strength before achieving the theoretical strength and its deformation capacity was limited; however, quick restoration is possible through a suitable rehabilitation technique. On the other hand, expensive repair or even complete replacement could be the decision for the column with the confinement failure mode. After that, a rehabilitation technique using external BFRP jacket was adopted. Performance-based design details guaranteeing the enhancement in the inelastic performance of both damaged columns were addressed and defined. Test results of the repaired columns confirmed that both reparability and the required repairing time of damage structures are dependent on the reinforcement details at the plastic hinge zone. Furthermore, lap-splice of longitudinal reinforcement could be applied as a key design-tool controlling reparability and restorability of RC structures after massive actions.

• 한국지진공학회논문집
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• 제11권4호
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• pp.1-11
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• 2007

This paper verifies the difference of the seismic behavior and seismic damage of the neighboring two reinforced concrete piers damaged by the 1995 Hyogoken Nanbu earthquake. The two piers were almost the same size, carrying slightly different dead load, and were provided with the same reinforcement arrangement except the amount of longitudinal reinforcement at the bottom portion of the piers. The pier with more reinforcement was completely collapsed due to this near field earthquake by shear failure at the longitudinal reinforcement cut-off while the other was only damaged at the bottom by flexure even though the longitudinal reinforcement cut-off was also existed at the mid height of the pier. According to the results of the pseudo dynamic test, the seismic damage was recognized to be greatly dependent on the ground motion characteristics even though the employed ground motions had the same peak acceleration. The severe damage was observed when the test employed the seismic wave that had strong influence to the longer period range compared to the initial natural period of the pier. On the other hand, based on the similar model experiment, the defect of gas-pressure welded splice of longitudinal reinforcement was revealed to save the piers against collapse due to the so-called fail-safe mechanism contrary to the intuitive opinion of some researchers. It was concluded that the primary cause of the collapse of the pier was the extremely strong intensity and peculiar characteristics of the earthquake motion according to both the site-specific and the structure-specific effects.

• Computers and Concrete
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• 제12권2호
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• pp.131-149
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• 2013

Various types of reinforcement splicing methods have been developed and implemented in reinforced concrete construction projects for achieving the continuity of reinforcements. Due to the complicated reinforcement arrangements and the difficulties in securing bar spacing, the traditional lap splicing method, which has been widely used in reinforced concrete constructions, often shows low constructability and difficulties in quality control. Also, lap spliced regions are likely to be over-reinforced, which may not be desirable in seismic design. On the other hand, mechanical splicing methods can offer simple and clear arrangements of reinforcement. In order to utilize the couplers for the ribbed-deformed bars, however, additional screw processing at the ends of reinforcing bars is typically required, which often lead to performance degradations of reinforced concrete members due to the lack of workmanship in screw processing or in adjusting the length of reinforcing bars. On the contrary, the use of screw-ribbed reinforcements can easily solve these issues on the mechanical splicing methods, because it does not require the screw process on the bar. In this study, the mechanical coupler suitable for the screw-ribbed reinforcements has been developed, in which any gap between the reinforcements and sleeve device can be removed by grouting high-flow inorganic mortar. This study presents the uniaxial tension tests on the screw-ribbed reinforcement with the mechanical sleeve devices and the cyclic loading tests on RC columns with the developed coupler. The test results show that the mechanical sleeve connection developed in this study has an excellent splicing performance, and that it is applicable to reinforced concrete columns with a proper confinement by hoop reinforcement.

• Journal of Genetic Medicine
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• 제7권1호
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• pp.1-8
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• 2010

Hemophilia A is a sex-linked recessive coagulation disorder associated with diverse mutations of the factor VIII gene and a variety of phenotypes. The type of mutation involved dictates the activity of factor VIII, and in turn the severity of bleeding episodes and development of alloantibodies against factor VIII (inhibitors). Missense mutations are the most common genetic risk factors for hemophilia A, especially mild to moderate cases, but carry the lowest risk for inhibitor development. On the other hand, intron 22 inversion is the most common mutation associated with severe hemophilia A and is associated with high risk of inhibitor formation. Large deletions and nonsense mutations are also associated with high risk of inhibitor development. Additional mutations associated with hemophilia A include frameshift and splice site mutations. It is therefore valuable to assess the mutational backgrounds of hemophilia A patients in order to to interpret their symptoms and manage their health problems.

• Earthquakes and Structures
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• 제15권4호
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• pp.419-429
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• 2018

The seismic vulnerability analysis of multi-span bridges can be based on the response of the piers, provided that deck, bearings and foundations remain elastic. The lateral response of an RC bridge pier can be affected by different mechanisms (i.e., flexure, shear, lap-splice or buckling of the longitudinal reinforcement bars, second order effects). In the literature, simplified formulations are available for mechanisms different from the flexure. On the other hand, the flexural response is usually calculated with a numerically-based Moment-Curvature diagram of the base section and equivalent plastic hinge length. The goal of this paper is to propose a simplified analytical solution to obtain the Moment-Curvature relationship for hollow circular RC sections. This based on calibrated polynomials, fitted against a database comprising 720 numerical Moment-Curvature analyses. The section capacity curve is defined through the position of 6 characteristic points and they are based on four input parameters: void ratio of the hollow section, axial force ratio, longitudinal reinforcement ratio, transversal reinforcement ratio. A case study RC bridge pier is assessed with the proposed solution and the results are compared to a refined numerical FEM analysis, showing good match.

• 한국구조물진단유지관리공학회 논문집
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• 제22권5호
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• pp.82-90
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• 2018

원자력 발전소에는 No.36(D36)이상의 대구경 철근이 사용되는데 이러한 대구경 철근으로 갈고리 정착을 할 경우, 기준에서 요구하는 구부림 및 갈고리 길이로 인해 설계 및 배근에 있어 큰 어려움을 겪을 수 있다. 이러한 문제를 해결하기 위한 방안으로 확대머리 철근을 사용할 수 있다. 2008년 개정된 ACI 318에서는 확대머리철근의 정착길이식을 도입하였으며, 제정 배경 연구를 근거로 하여 횡보강근의 영향력을 무시하고 있다. 그러나 확대머리 철근이 겹침이음이나 컷오프 구간에서 사용될 경우, 인장재에 의해 피복 콘크리트를 밀어내는 힘이 발생하여 횡보강근에 작용하는 인장력이 크게 증가한다. 본 연구의 목적은 휨을 받는 부재 내에 정착된 확대머리 철근의 정착성능에 대한 횡보강근의 영향력을 평가하는 것으로, 이를 위해 횡보강근의 간격을 변수로 한 대구경 확대머리 철근의 정착실험을 수행하였다. 실험방법으로는 컷오프 구간을 모사한 실험을 수행하였으며, 확대머리 철근으로는 D43의 대구경 철근을 사용하였다. 실험 결과, 횡보강근이 없는 실험체의 경우 정착구간의 쪼갬파괴에 이어 단부의 하중이 확대머리 부근의 콘크리트에 직접적으로 작용하면서 상부 피복 콘크리트가 부재에서 탈락하는 취성적인 파괴형태가 나타났다. 또한 확대머리 철근의 발현강도가 항복강도의 절반밖에 못 미치는 매우 낮은 내력을 보였다. 이에 반해 횡보강근이 배근된 실험체의 경우 경우 횡보강근이 실험체 단부의 하중에 직접적으로 저항함에 따라 실험체 내력이 큰 폭으로 상승하였다.