• 제목/요약/키워드: cyclic behaviors

검색결과 303건 처리시간 0.026초

비선형 이동경화법칙에 기초한 점성토의 거동 특성 (A Study on Clay Behavior Characteristics Based on Non-Linear Kinematic Hardening Rule)

  • 김용성
    • 한국농공학회지
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    • 제44권4호
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    • pp.114-122
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    • 2002
  • Up to now, many constitutive models for clay have been proposed and studied based on the elasto-plastic or elasto-viscoplastic theory and it has been recognized that the effect of time on the loading process is a salient feature. In the present study, cyclic behavior characteristics of clay was studied with a viscoelastic-viscoplastic constitutive model for clay based on the non-linear kinematic hardening rule. In order to examine the behavior of clay several cyclic untrained triaxial tests and also their numerical simulations were performed. As results of that, it was found that the proposed model can well describe cyclic behaviors of clay such as frequency dependent characteristics, and have the high feasibility of numerical simulation for dynamic analysis.

카본시트튜브로 구속된 원형기둥의 휨내력 및 비선형 특성에 대한 연구 (Flexural Capacity and Non-Linear Characteristic Evaluation of Circular Column Confined by Carbon Sheet Tube)

  • 이경훈;유영종;김희철;홍원기;이영학
    • 한국구조물진단유지관리공학회 논문집
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    • 제11권3호
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    • pp.143-150
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    • 2007
  • 본 연구에서는 카본시트튜브로 구속된 원형기둥에 반복 횡하중을 가하여 기둥의 휨내력을 평가하는 실험을 수행하였다. 중립축을 기준으로 압축 및 인장측 단면의 모멘트를 이용하여 공칭모멘트를 계산하는 등가응력블록계산법을 소개하였다. 또한 실험결과를 분석하여 횡 하중에 대한 거동을 예측할 수 있는 회귀식을 마련하여 실험결과와 비교하였다.

반복과대하중에 의한 피로파괴거동의 고찰 (An evaluation of Fatigue Crack Propagation Behaviors on Cyclic Overload Test)

  • 김용수;신근하;강동명;김병석
    • 한국안전학회지
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    • 제7권2호
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    • pp.47-56
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    • 1992
  • The retardation effect of fatigue crack propagation after cyclic overloading seems to be affected by strain hardening exponent. Namely, for the material with high values of n, the delay effect is found to be severe. We proposed a modified crack retardation equation which may apply the retardation of fatigue crack growth after a cyclic overloading, as (da/dN)'$_{cyc}$=($\mu$n+λ)B $\Delta$ $K^{q}$ /[(1- $R_{eff}$) $K_{cf}$$\Delta$K]. where, $R_{eff}$ is effective stress ratio [=( $K_{min}$-K, os)/( $K_{max}$$K_{res}$)] The constants $\mu$=-0.5 and λ=0.6, and the values are found to be identical for materials such as aluminum (A 1060), steel (SS 34), brass ( $B_{s}$ SIB) and stainless steel (SUS 304) used in this investigation. (SUS 304) used in this investigation.ation.n.n.

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송전철탑의 풍응답 감소를 위한 마찰형 보강기구의 에너지 소산특성 분석 실험 (Experimental Investigation on the Energy Dissipation of Friction-type Reinforcing Members Installed in a Transmission Tower for Wind Response Reduction)

  • 박지훈;문병욱;이성경;민경원
    • 한국소음진동공학회논문집
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    • 제17권7호
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    • pp.649-661
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    • 2007
  • Friction-type reinforcing members(FRM) to enhance the resistance to wind loads of a transmission tower through both stiffness strengthening and damping increase are energy dissipation devices that utilize bending deflection of a tower leg. In this paper, the hysteretic behavior of the transmission tower structure with FRMs was experimentally investigated through cyclic loading tests on a half scale substructure model. Firstly, the variation of friction forces and durability of the FRM depending on the type of friction-inducing materials used in the FRM were examined by performing the cyclic loading tests on the FRM. Secondly, cyclic loading tests of a half-scale two-dimensional substructure model of a transmission tower with FRMs were conducted. Test results show that the FRM, of which desired maximum friction force is easily regulated by adjusting the amplitude of the torque applied to the bolts, have stable hysteretic behaviors and it is found that there exists the optimum torque depending on a design load by investigating the amount of energy dissipation of the FRMs according to the increase of torque.

송전철탑의 풍응답 감소를 위한 마찰형 보강기구의 에너지 소산특성 분석 실험 (Experimental Investigation on the Energy Dissipation of Friction-type Reinforcing Members Installed in a Transmission Tower for Wind Response Reduction)

  • 박지훈;문병욱;이성경;민경원
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2007년도 춘계학술대회논문집
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    • pp.568-577
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    • 2007
  • Friction-type reinforcing members (FRM) to enhance the resistance to wind loads of a transmission tower through both stiffness strengthening and damping increase are energy dissipation devices that utilize bending deflection of a tower leg. In this paper, the hysteretic behavior of the transmission tower structure with FRMs was experimentally investigated through cyclic loading tests on a half scale substructure model. Firstly, the variation of friction forces and durability of the FRM depending on the type of Friction-inducing materials used in the FRM were examined by performing the cyclic loading tests on the FRM. Secondly, Cyclic loading tests of a half-scale two-dimensional substructure model of a transmission tower with FRMs were conducted. Test results show that the FRM, of which desired maximum friction force is easily regulated by adjusting the amplitude of the torque applied to the bolts, have stable hysteretic behaviors and it is found that there exists the optimum torque depending on a design load by investigating the amount of energy dissipation of the FRMs according to the increase of torque.

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반복단순전단 시험에 의한 패각질 모래의 동적 거동 (Dynamic Behaviors of Shelly Sand in Cyclic Simple Shear Test)

  • 윤여원;윤길림;최재권;김재권;김승현
    • 한국지반공학회:학술대회논문집
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    • 한국지반공학회 2006년도 춘계 학술발표회 논문집
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    • pp.1358-1366
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    • 2006
  • In order to study the effects of shell contents on the liquefaction resistance of the shelly sand, NGI cyclic simple shear tests were performed for the shelly sands with shell contents of 0%, 5%, 10%, 20% and 30% under the effective vertical stress of 50kPa, 100kPa and 150kPa for 40% and 55% of relative density, respectively. Cyclic simple shear test results showed that for the low effective vertical stress, liquefaction resistance increased rapidly with the increase of shell contents in both 40% and 55% relative density. On the other hand, for the high effective vertical stress, the liquefaction resistance increased slightly in 40% relative density whereas the resistance was almost same in 55% relative density. Liquefaction resistance decreased with increasing effective vertical stress for both 40% and 55% relative density. In the same effective vertical stress and shell contents, liquefaction resistance increased with the increase of relative density of sands.

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슈퍼오스테나이트 스테인리스강의 순환동전위 분극특성에 미치는 해수온도의 영향과 손상 거동에 관한 미시적 분석 (Effect of Seawater Temperature on the Cyclic Potentiodynamic Polarization Characteristics and Microscopic Analysis on Damage Behavior of Super Austenitic Stainless Steel)

  • 황현규;김성종
    • Corrosion Science and Technology
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    • 제20권6호
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    • pp.412-425
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    • 2021
  • Because austenitic stainless steel causes localized corrosion such as pitting and crevice corrosion in environments containing chlorine, corrosion resistance is improved by surface treatment or changes of the alloy element content. Accordingly, research using cyclic potentiodynamic polarization experiment to evaluate the properties of the passivation film of super austenitic stainless steel that improved corrosion resistance is being actively conducted. In this investigation, the electrochemical properties of austenitic stainless steel and super austenitic stainless steel were compared and analyzed through cyclic potentiodynamic polarization experiment with varying temperatures. Repassivation properties were not observed in austenitic stainless steels at all temperature conditions, but super austenitic stainless steels exhibited repassivation behaviors at all temperatures. This is expressed as α values using a relational formula comparing the localized corrosion rate and general corrosion rate. As the α values of UNS S31603 decreased with temperature, the tendency of general corrosion was expected to be higher, and the α value of UNS N08367 increased with increasing temperatures, so it is considered that the tendency of localized corrosion was dominant.

Dynamic Behaviors of Redox Mediators within the Hydrophobic Layers as an Important Factor for Effective Microbial Fuel Cell Operation

  • Choi, Young-Jin;Kim, Nam-Joon;Kim, Sung-Hyun;Jung, Seun-Ho
    • Bulletin of the Korean Chemical Society
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    • 제24권4호
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    • pp.437-440
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    • 2003
  • In a mediator-aided microbial fuel cell, the choice of a proper mediator is one of the most important factors for the development of a better fuel cell system as it transfers electrons from bacteria to the electrode. The electrochemical behaviors within the lipid layer of two representative mediators, thionin and safranine O both of which exhibit reversible electron transfer reactions, were compared with the fuel cell efficiency. Thionin was found to be much more effective than safranine O though it has lower negative formal potential. Cyclic voltammetric and fluorescence spectroscopic analyses indicated that both mediators easily penetrated the lipid layer to pick up the electrons produced inside bacteria. While thionin could pass through the lipid layer, the gradual accumulation of safranine O was observed within the layer. This restricted dynamic behavior of safranine O led to the poor fuel cell operation despite its good negative formal potential.

Evaluation of seismic criteria of built-up special concentrically braced frames

  • Izadi, Amin;Aghakouchak, Ali A.
    • Steel and Composite Structures
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    • 제29권1호
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    • pp.23-37
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    • 2018
  • In this paper, seismic provisions related to built-up special concentrically braced frames (BSCBFs) are investigated under cyclic loading using non-linear finite element analysis of a single-bay single-story frame. These braces, which contain double angle and double channel brace sections, are considered in two types of single diagonal and X-braced frames. The results of this study show that current seismic provisions such as observing the 0.4 ratio for slenderness ratio of individual elements between stitch connectors are conservative in BSCBFs, and can be increased according to the type of braces. Furthermore, such increments will lead to decreasing or remaining the current middle protected zone requirements of each BSCBFs. Failure results of BSCBFs, which are related to the plastic equivalent strain growth of members and ductility capacity of the models, show that the behaviors of double channel back-to-back diagonal braces are more desirable than those of similar face-to-face ones. Also, for double angle diagonal braces, results show that the failure of back-to-back BSCBFs occurs faster in comparison with face-to-face similar braces. In X-braced frames, cyclic and failure behaviors of built-up face-to-face models are more desirable than similar back-to-back braces in general.