• 제목/요약/키워드: external steel

검색결과 635건 처리시간 0.025초

PEMFC용 분리판 표면코팅 및 부식성 평가 (Surface Coating and Corrosion Characteristics of Bipolar Plates of PEMFC Application)

  • 강경민;김동묵;최정식;차인수;윤영훈
    • 한국수소및신에너지학회논문집
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    • 제22권2호
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    • pp.199-205
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    • 2011
  • Stainless steel 304 and 316 plates were deposited with the multi-layered coatings of titanium film (0.1 um) and gold film (1-2 um) by an electron beam evaporation method. The XRD patterns of the stainless steel plates modified with the multi-layered coatings showed the crystalline phases of the external gold film and the stainless steel substrate. Surface microstructural morphologies of the stainless steel bipolar plates modified with multi-layered coatings were observed by AFM and FE-SEM images. The external gold films formed on the stainless steel plates showed micro structure of grains of about 100 nm diameter. The grain size of the external surface of the stainless steel plates increased with the gold film thickness. The electrical resistance and water contact angle of the stainless steel bipolar plates covered with multi-layered coatings were examined with the thickness of the external gold film.

외부 프리스트레싱으로 보강된 R.C 보에서 강재량 및 텐던깊이에 따른 프리스트레싱 강재의 극한응력 (Ultimate Stress of Prestressing Steel with Different Reinforcement and Tendon Depth in R.C Beams Strengthened by External Prestressing)

  • 박상렬
    • 콘크리트학회논문집
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    • 제15권4호
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    • pp.585-593
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    • 2003
  • 본 연구는 외부 프리스트레싱으로 보강된 철근콘크리트 보에 관한 문헌연구와 프리스트레싱 강재의 극한응력 예측식의 개발, 극한응력에 영향을 미치는 변수들에 대한 실험 등이다. 새로운 통합 예측식 개발을 위하여 비부착 프리스트레싱 강재의 극한응력에 대한 ACI 시방식을 확장하고 분석하였다. 본 논문에서는 외부 프리스트레싱 강재의 극한응력에 대한 새로운 합리적 예측식을 제안하고 있는데, 프리스트레싱 강재와 중립축의 깊이 비의 함수로서 표현하여 내부 철근의 영향을 고려하고 있다. 실험연구에서는 프리스트레싱 강재의 극한응력에 가장 큰 영향을 미치는 실험변수를 가지고 외부 프리스트레싱으로 보강된 철근콘크리트 보를 제작하여 실험하였다. 실험연구에서 채택한 영향인자들은 배부철근비, 외부 프리스트레싱 강재비, 지간과 PS강재높이 비 등이다. 실험결과는 분석되어 외부 프리스트레싱 강재의 극한응력에 대한 제안된 예측식의 합리성과 적용성을 확인하였다.

An innovative experimental method to upgrade performance of external weak RC joints using fused steel prop plus sheets

  • Kheyroddin, Ali;Khalili, Ali;Emami, Ebrahim;Sharbatdar, Mohammad K.
    • Steel and Composite Structures
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    • 제21권2호
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    • pp.443-460
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    • 2016
  • In this paper, the efficiency and effectiveness of two strengthening methods for upgrading behavior of the two external weak reinforced concrete (RC) beam-column joints were experimentally investigated under cyclic loading. Since two deficient external RC joints with reduced beam height and low strength concrete were strengthened using one-way steel prop and curbs with and without steel revival sheets on the beam. The cyclic performance of these strengthened specimens were compared with two another control external RC beam-column joints, one the standard RC joint that had not two mentioned deficiencies and another had both. Therefore, four half-scale RC joints were tested under cyclic loading.The experimental results showed that these innovative strengthening methods (RC joint with revival sheet specially) surmounted the deficiencies of weak RC joints and upgraded their performance and bearing capacity, stiffness degradation, energy absorption, up to those of standard RC joint. Also, results exhibited that the prop at joint acted as a fuse element due to adding steel revival sheets on the RC beam and showed better behavior than that of the specimen without steel revival sheets. In other words by stiffening of beam, the prop collected all damages due to cyclic loading at itself and acted as the first line of defense and prevented from sever damages at RC joint.

포스트텐션 콘크리트 보에서 비부착 외부강봉의 응력 (Stress of External Steel Rod in Post-Tensioned Concrete Beam)

  • 이수헌;강현구;신경재
    • 한국공간구조학회논문집
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    • 제15권1호
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    • pp.47-55
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    • 2015
  • This paper shows the simplified equation to predict the ultimate moment capacity and corresponding rod stress in reinforced concrete beam with external post-tensioning rods. Because the stress of external post-tensioning rod depends on the beam deflection, the previous analytical model for post-tensioned beams requires a tedious iteration process. Also, the stress equations in ACI code or other researchers' models are suitable only for internal tendons in concrete beams. In this study, given the lack of analytical approaches to predict the nominal stress of the external unbonded rod, a simple and robust equation has been proposed for externally post-tensioned concrete beams. It is concluded that the proposed equation predicted the stress of external steel rods in post-tensioned concrete beams reasonably well.

Seismic performance of beam-to- SST column connection with external diaphragm

  • Rong, Bin;Yin, Shuhao;Zhang, Ruoyu;Wang, Lei;Yang, Ziheng;Li, Hongtao;Wan, Wenyu
    • Steel and Composite Structures
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    • 제37권6호
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    • pp.633-647
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    • 2020
  • This paper aims to study the seismic performance of external diaphragm connection between SST (square steel tube) column and H-shaped beam through experimental and analytical study involving finite element (FE) method and theoretical analysis. In the experimental study, three external diaphragm connection specimens with weak panel zone were tested under axial pressure on the top of the column and antisymmetric cyclic loads at the beam end to investigate the seismic performance of the panel zone. The hysteretic behavior, failure mode, stiffness and ductility of the specimens were discussed. Key point to be explored was the influence of the thickness of the steel tube flange on the shear capacity of the specimens. In the analytical study, three simplified FE models were developed to simulate the seismic behavior of the specimens for further analysis on the influence of steel tube flange. Finally, four existing calculation formulas for the shear capacity of the external diaphragm connection were evaluated through comparisons with the results of experiments and FE analysis, and application suggestions were put forward.

철골조학교(鐵骨造學校) 스틸스터드 벽체(壁體)의 단열(斷熱) 및 결로방지(結露防止) 성능(性能) 평가(評價)를 위한 실험적(實驗的) 연구(硏究) (Experimental Study to Evaluate the Thermal and Condensation Performance of Steel Stud Walls in Steel-Framed Schools)

  • 유영동;김갑득
    • 교육시설
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    • 제6권4호
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    • pp.16-23
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    • 1999
  • The thermal and condensation performance of steel stud walls are monitored in steel-framed schools of Ee-Wol Elementary School and kindergarten using temperature and humidity sensors installed. The monitoring process carried out during the summer and winter period, shows decrement effect of the external heat flow to be quite remarkable and excellent. And steel stud walls provides a highly efficient time-lag effect in spite of its light weight property, with 30 minutes to 4 hours time-lag for external heat flow, which variation mainly depends on its location of each part of the wall. Any condensation phenomena are not observed in either external or internal surfaces.

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API-581에 의한 정량적 위험기반검사에서 스테인리스강의 외부부식에 의한 사고발생 가능성 해석 (- Analysis of Likelihood of Failure for the External Corrosion of Stainless Steel through the Quantitative Risk Based Inspection Using API-581 -)

  • 이헌창;김환주;김태옥
    • 대한안전경영과학회지
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    • 제6권3호
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    • pp.99-107
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    • 2004
  • Likelihood of failure (LOF) for the external corrosion of stainless steel, which affect to a risk of facilities, was analyzed quantitatively through the risk based inspection using API-581 BRD. We found that the technical module subfactor (TMSF) decreased as the inspection number increased and it increased as the inspection effectiveness and the used year increased, and that the TMSF showed high value for the case of the marine/cooling tower drift area as a corrosion driver, In this condition, the LOF for the external corrosion of stainless steel had lower than that for the carbon and low alloy steels

외부 프리스트레스트 콘크리트 부재의 극한상태에서의 강선응력예측식 제안 (Prediction of Prestressing Steel Stress at Ultimate State of Prestressed Concrete Members with External Unbonded Tendons)

  • 오병환;유성원
    • 콘크리트학회논문집
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    • 제11권6호
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    • pp.13-24
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    • 1999
  • The external, unbonded prestressed concrete(PSC) members exhibit very different structural behavior from that of internal bonded PSC members because of eccentricity change and slip occurrence during loading process. The purpose of the present study is to propose the ultimate failure stresses of prestressing (PS) steels for those external unbonded PSC members. To this end, a comprehensive analysis has been made using the nonlinear finite element analysis program developed recently for external unbonded PSC members by authors. A series of major influencing variables have been included in the analysis. It was found that the span-depth ratio, neutral axis depth-effective depth ratio, load geometry, amount of ordinary steel, and prestressing steel ration have great influence for the ultimate failue stress of PS steel is preposed and is compared with experimental dat as well as existing formulas for internal unbonded members. The Comparison indicates that the proposed equation agrees relatively well with experimental data and that existing formulas including ACI and AASHTO equations show some discrepancies from experimental ones. The present study allows more realistic analysis and design of prestressed concrete structures with external unbonded tendons.

스틸밴드로 외부 보강된 철근콘크리트 기둥의 부착강도에 관한 실험적 연구 (An Experimental Study on Splitting Bond Strength of RC Column Reinforced with External Steel-Band)

  • 김창식;윤승조;허승웅;윤필중
    • 한국구조물진단유지관리공학회 논문집
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    • 제18권6호
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    • pp.41-49
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    • 2014
  • 실험에서는 스틸밴드로 외부보강된 철근콘크리트 부재의 부착강도에 관한 연구를 진행하였으며 총 9개의 실험체를 제작하여 인발 실험을 실시하였다. 실험결과 스틸밴드의 수와 초기응력의 증가에 따라 부착강도는 증가하는 것으로 나타났다. 이것은 스틸밴드에 의해 가해지는 긴장력으로부터 철근과 콘크리트간 횡방향에 의한 구속력 증가로 판단된다. 변수로한 실험결과들을 통하여 스틸밴드로 외부보강된 철근콘크리트 부재에 관한 부착강도 산정식을 검토하였다.

Evaluating performance of the post-tensioned tapered steel beams with shape memory alloy tendons

  • Hosseinnejad, Hossein;Lotfollahi-Yaghin, Mohammad Ali;Hosseinzadeh, Yousef;Maleki, Ahmad
    • Earthquakes and Structures
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    • 제23권3호
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    • pp.221-229
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    • 2022
  • The external post-tension technique is one of the best strengthening methods for reinforcement and improvement of the various steel structures and substructure components such as beams. In the present work, the load carrying capacity of the post-tensioned tapered steel beams with external shape memory alloy (SMA) tendons are studied. 3D nonlinear finite element method with ABAQUS software is used to determine the effects of the increase in the flexural strength, and the improvement of the load carrying capacity. The effect of the different parameters, such as geometrical characteristics and the post-tension force applied to the tendons are also studied in this research. The results reveal that the external post-tension with SMA tendons in comparison with the steel tendons causes a significant improvement of the loading capacity. According to this, using SMA tendon for the reinforcement of the tapered beams causes a decrease in weight of these structures and as a consequence causes economic benefits for their application. This method can be used extensively for steel beams due to low executive costs and simplicity of the operation for post-tension.