• Title/Summary/Keyword: 정착 모드

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Flexural Behavior of RC Beams Strengthened with CFRP Plate Using Multi-directional Channel-type Anchorage System (다방향 채널형 단부정착장치를 이용한 CFRP판 보강 RC 보의 휨거동)

  • Hong, Ki Nam;Han, Sang Hoon
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.12 no.2
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    • pp.171-180
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    • 2008
  • The aim of this paper is to clarify the structural performance of RC beams strengthened with Carbon Fibre Reinforced Polymer(CFRP) plates using channel-type anchorage system. Twelve RC beams were specifically designed without and with a channel-type anchorage system, which was carefully detailed to enhance the benefits of the strengthening plates. All the twelve beams were identical in terms of their geometry but varied in their internal reinforcement, concrete strength. All the beams were tested under four point bending and extensively instrumented to monitor strains, cracking, load capacity and failure modes. The structural response of all the twelve beams is then critically analyzed in terms of deformability, strength and failure processes. It is shown that with a channel-type anchorage system, a brittle debonding failure of a strengthened beam can be transformed to an almost ductile failure with well-defined enhancement of structural performance in terms of both deformation and strength.

A Study on the Basic Development Length of GFRP Rebar With Ribs (이형 GFRP 보강근의 기본정착길이에 대한 연구)

  • Moon, Do Young
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.30 no.5A
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    • pp.485-493
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    • 2010
  • GFRP rebar with ribs resemble those of deformed steel rebar was developed in 2005. It was reported that ribs of the GFRP rebar were sheared off due to the lower shear strength of polymer. In this study, the basic development length of the GFRP rebar was investigated through pull-out tests, models specified in ACI440.1R-03 and -06, and empirical model derived by Cosenza et al. (2002). As a results of pull-out tests, the critical embeddment length, which is defined as the length when failure mode is changed from pull-out to bar fracture, was 20 times of bar diameter for GFRP rebar and was 15 times for steel rebar. It is believed that the basic development of the GFRP rebar is 21 times of bar diameter, which is determined from the application of average bond strength into the model equation specified in ACI440.1R-03. Compared to the model equation in ACI440.1R-06, that in ACI440.1R-03 is recommendable for design purpose. The Cosenza et al.'s model underestimates the basic development length of the GFRP rebar.

An Automatic Gain Control Circuit for Burst-mode Optical Signal reception (버스트 모드 광 신호 수신을 위한 자동 이득제어 회로)

  • 기현철
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.40 no.12
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    • pp.31-38
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    • 2003
  • In this paper, we proposed a new structural AGC(Automatic Gain Control) circuit with extremely short settling time using high speed operation characteristics of a clipper. We investigated its operation characteristics in analysis. We also designed a burst-mode preamplifier for 1.25Gbps EPON systems using commercial foundry and investigated its characteristics by comparing the results of the designed and those of the analyzed. The characteristics of the designed circuit are in good agreement with those of the analyzed. As a result, it is shown that it is possible to realize extremely short settling time of under 1㎱.

Dynamic Characteristics of Cable-Stayed Anchorage considering Cracks at Bolt and Welding Connection (용접 및 볼트 연결부 균열을 고려한 사장교 케이블 정착부의 동특성 해석)

  • Kim, Chul Young;Kim, Sung Bo;Jung, Woo Tai
    • Journal of Korean Society of Steel Construction
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    • v.11 no.4 s.41
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    • pp.351-362
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    • 1999
  • Damage detection methods which utilize the change in dynamic characteristics are very hard to apply to large civil structures since local damage hardly affects global dynamic characteristics. But, if there is a very important and critical member and we focus only on the local behavior of it, it would be possible to detect damage from the change in local dynamic characteristics, such as natural frequencies and mode shapes .In this study, the cable anchorage part of a cable-stayed bridge under construction is modeled and analyzed by commercial finite element program, ABAQUS. It has both welding and bolting connections with a cable and a stiffening plate, and has a possible high stress concentration portions in it. Several damage scenarios such as crack through the welding or crack through the bolting connection are examined. The result shows that the local natural frequencies of the damaged member decrease up to 16% compared with that of the undamaged member. It is concluded that there is quite a high feasibility that the damage of the cable anchorage can be detected by measuring local dynamic characteristics.

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Shear Performance of Wood-Concrete Composite I - Shear Performance with Different Anchorage Length of Steel Rebar in Wood - (목재-콘크리트 하이브리드 부재의 전단성능 I - 목재 내 철근 정착 길이에 따른 전단성능 평가 -)

  • Lee, Sang-Joon;Eom, Chang-Deuk;Kim, Kwang-Mo
    • Journal of the Korean Wood Science and Technology
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    • v.40 no.3
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    • pp.186-193
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    • 2012
  • The wood-concrete composite can be effectively applied for bridge superstructure, and the concept of fully composite action between each member is one of the most important consideration. Until now, related researches have been done mainly in North America and EU countries not enough to cover the fundamental studies. Therefore, this study is planned to perform one of the important issue for using the wood-concrete composite. The objective of this study is evaluation of shear performance with different anchorage length of steel rebar in wood. Prediction of the yield mode and the reference design value was firstly performed as the preliminary investigation. Then, initial stiffness, yield load and maximum load were derived from the shear test due to different anchorage length of the steel rebar (SD30A in Korean Standard) in wood. It was found out from this study that initial stiffness and yield load are not related with the anchorage length over 20 mm of anchorage length while maximum load shows increasing tendency till 60 mm of anchorage length. Pullout strength of inserted steel rebar in wood is considered to be one reason and this was also verified with the x-ray radiography.

Fuzzy Sliding Mode Controller for a Robot Manipulator with Passive Joints (수동 관절을 가진 로봇 매니퓰레이터를 위한 퍼지 슬라이딩 모드 기법을 이용한 제어기)

  • Kim, Won;Kim, Min-Seong;Shin, Jin-Ho;Lee, Ju-Jang
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.13 no.1
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    • pp.31-38
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    • 1999
  • In this paper, we proposed a fuzzy sliding mode controller for a robot manipulator with passive joints. A robot manipulator with passive joints which is not equipped with actuators is a kind of underactuated systerms. The control of underactuated manipulators is more difficult than that of fully-actuated ones. Though the sliding mode control technique has a robust charocteristics to prrarreter uncertainties and external disturbances, the chattering phenomena becorne one of the major problems in application to the real plant. plant.

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An Automatic Threshold Control Circuit Adaptive to Burst Optical signal Levels (버스트 광 신호 레벨 적응형 기준레벨 자동 발생회로)

  • 기현철
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.40 no.12
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    • pp.24-30
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    • 2003
  • In this paper, we proposed an adaptive ATC(Automatic Threshold Control) circuit with more decreased settling time by improving the structure of the peak detector. We showed that it could reduce a good deal of the settling time because it showed less than half the error voltage ratio that the ATC circuit with conventional structure showed in analysis. We also designed a burst-mode ATC circuit for the 1.25Gbps EPON system using a commercial foundry. It produced the reference levels in very short time, 6㎱ in 40 ㏈ input dynamic range.

Sliding Mode Controller Design Considering Weight (가중치를 고려한 슬라이딩 모드 제어기 설계)

  • 임동균;서병설
    • The Transactions of the Korean Institute of Power Electronics
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    • v.4 no.3
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    • pp.223-230
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    • 1999
  • A conventional sliding mode control approach is often impractical or difficult when it is applied to high order process b because the number of tuning parameters in the sliding mode controller increases with the order of the plant. C Camacho(l996) proposed a design method of a fixed structure sliding mode controller based on a first order plus dead t time approximation to the higher-order process. But, his method has such problems as chattering, over‘shoot, and c command following due to the Taylor the approximation en‘ors for the time delay term of the first order model. In this p paper, a new design technique for a sliding mode controller based on the modified Taylor approximation considered a w weight is developed to improve the Camacho's problems.

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On-Line Sliding Mode Controller Design from a Single Closed Loop Test (단일 폐루프 테스트를 통한 온라인 슬라이딩 모드 제어기 설계)

  • Bae Jun-hyung;Lim Dong-kyun;Suh Byung-sulh
    • Journal of the Institute of Electronics Engineers of Korea SC
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    • v.42 no.6
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    • pp.1-8
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    • 2005
  • The calculation of parameters of a process model is modified to find better sliding mode controller for a process. A design method by Camacho has such problems as chattering and overshoot due to the Taylor the approximation errors for the time delay term of the first order model. In this paper, a new design technique for a sliding mode controller is proposed by introducing the modified Pade approximation considering the weight factor. With the proposed method, the process response can be directly used to estimate the system parameters without any numerical processing.

Inelastic Behavior of Post-tensioned Wide Beam System with different Reinforcement ratios within Column core (포스트텐션을 도입한 넓은 보에서 기둥 폭 내부에 배근된 보강재의 정착비에 따른 비탄성 거동 평가)

  • Choi Yun-Cheul;Lim Jae-Hyung;Moon Jeong-Ho;Lee Li-Hyung;Kwon Ki-Hyuk
    • Journal of the Korea Concrete Institute
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    • v.17 no.1 s.85
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    • pp.85-94
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    • 2005
  • Post-tensioned Precast concrete System(PPS) consists of U-shaped precast wide beams and concrete column. The continuity of beam-column joint is provided with floor concrete cast on the PC shell beam and post-tensioning. The purpose of this paper is to evaluate the response of PPS interior beam-column joint subjected to cyclic lateral loading. To this end, an experimental investigation was performed with three half-scale specimens of interior connection. The design parameters are the amount of beam reinforcement placed inside the joint core. The test results showed that cracks were distributed well without my significant degradation of strength and ductility. Also, it was found that the prestressing may affect to alter the torsional crack angle. And the specimens sufficiently resist up to limiting drift ratio of 0.035 in accordance with the provisional by ACl of acceptance criteria for concrete special moment frames.