• 제목/요약/키워드: Dynamic Dissipation

검색결과 345건 처리시간 0.025초

상사법칙 검증을 위한 1-g 모형실험과 원심모형실험의 비교 연구 (Comparison of 1-g and Centrifuge Model Tests for Similitude Laws)

  • 김성렬;황재익;김명모
    • 한국지반공학회논문집
    • /
    • 제22권5호
    • /
    • pp.59-67
    • /
    • 2006
  • 동일한 흙으로 조성된 모형지반에 대하여 1-g 모형실험과 원심모형실험을 수행하고 그 결과를 비교하였다. 원형지반은 10m 두께의 수평하고 느슨한 포화 사질토 지반으로 가정하였다. 1-g 모형실험은 1/20 축소모형, 원심모형실험은 1/40 축소모형을 이용하였다. 원심모형실험의 경우 점성유체를 사용하여 동적시간에 대한 상사비와 과잉간극수압소산시간에 대한 상사비가 동일하도록 하였다. 원심모형실험의 계측결과는 원형지반의 거동으로 가정하였다. 그리고, 1-g모형실험에 정상상태개념 및 두 가지 시간상사비 등을 적용하여 원형지반의 거동을 모사하고자 하였다. 동일한 위치에서의 과잉간극수압, 지반가속도 그리고 지표 침하량 등을 계측하여 비교하였다. 실험결과 지반의 투수계수가 작아서 진동 중 과잉간극수압 소산의 영향이 작고, 소산시간상사비를 적절하게 결정하면 1-g 모형실험으로부터 원형지반의 과잉간극수압 거동을 모사할 수 있는 것으로 나타났다.

저전력 입출력을 위한 반복적인 버스반전 부호화 (Recursive Bus-Invert Coding for Low-Power I/O)

  • 정덕기;손윤식정정화
    • 대한전자공학회:학술대회논문집
    • /
    • 대한전자공학회 1998년도 추계종합학술대회 논문집
    • /
    • pp.1081-1084
    • /
    • 1998
  • In this paper, we propose the bus coding technique for low power consumption. For CMOS circuit most power is dissipated as dynamic power for charging and discharging node capacitances.Though the I/O and bus are likely to have the very large capacitances associated with them and dissipate much of the power dissipated by an IC, they have little beenthe special target for power reduction. The conventional Bus-Invert coding method can't decrease the peak power dissipation by 50% because the additional invert signal line can invoke a transition at the time when Bus-Invert coding isn't used to code original bus data. The proposed technique always constraints the Hamming distance between data transferred sequentially to be below the half of the bus width, and thus decrease the I/O peak power dissipation and the I/O average power dissipation.

  • PDF

유효감쇠비를 이용한 점탄성 감쇠기의 설계 (Design of Viscoelastic Dampers Using Effective Damping Ratio)

  • 최현훈;김진구
    • 한국지진공학회:학술대회논문집
    • /
    • 한국지진공학회 2001년도 춘계학술대회 논문집
    • /
    • pp.371-378
    • /
    • 2001
  • To enhance seismic performance of a structure ATC-40 and FEMA-273 propose technical strategies such as increasing strength, altering stiffness, and reducing demand by employing base isolation and energy dissipation devices. Specifically the energy dissipation devices directly increase the ability of the structure to dampen earthquake response. However nonlinear dynamic time history analysis of a structure with energy dissipation devices is complicated and time consuming. In this study a simple and straightforward procedure is developed using effective damping ratio to obtain the required amount of viscoelastic dampers in order to meet given performance objectives. Parametric study has been performed for the period of the structure, yield strength, and the stiffness after the first yield. According to the analysis results, earthquake demand and required damping ratio were reduced by installing viscoelastic dampers. The results also show that with the addition of the supplemental damping evaluted by the proposed method the performance of the model structures are well restrained within the target point.

  • PDF

보강재에 따른 방호패널의 에너지 소산능력에 대한 실험적 연구 (An Experimental Study on Energy Dissipation Capacity of protection according to the reinforcement panel)

  • 이예찬;김규용;석원균;최병철;사수이;남정수
    • 한국건축시공학회:학술대회논문집
    • /
    • 한국건축시공학회 2022년도 봄 학술논문 발표대회
    • /
    • pp.113-114
    • /
    • 2022
  • The purpose of this study is to identify the rear energy transfer amount and time delay capability of the protection panel that has been impated by a projectile and the protection panel reinforced the foam polypropylene on the rear of the fiber reinforced cement itious composites, and compared and analyzed the load resistance capacity, energy dissipation capacity, and impact delay capacity when dynamic extreme load were applied to the specimen.

  • PDF

DYNAMIC CHARACTERISTICS OF SCALED-DOWN W-BEAMS UNDER IMPACT

  • Hui, T.-Y.-J.;Ruan, H.-H.;Yu, T.-X.
    • International Journal of Automotive Technology
    • /
    • 제4권1호
    • /
    • pp.31-40
    • /
    • 2003
  • W-beam guardrail system has been the most popular roadside safety device around the world. Through large plastic deformation and corresponding energy dissipation, a W-beam guardrail system contains and re-directs out-of-control vehicles so as to reduce the impact damage on the vehicle occupants and the vehicles themselves. In this paper, our recent experiments on 1 : 3.75 downscaled W-beam and the beam-post system are reported. The static and impact test results on the load characteristics, the global response and the local cross-sectional distortion are reveled. The effects of three different end-boundary conditions for the beam-only testing are examined. It is found that the load characteristics are much dependent on the combined contribution of the local cross-sectional distortion and the end-supporting conditions. The energy Partitioning between the beam and the supporting Posts in the beam-Post-system testing were also examined. The results showed that the energy dissipation partitioning changed with the input impact energy. Finally, a simple mass-spring model is developed to assess the dynamic response of a W-beam guardrail system in response to an impact loading. The model's prediction agrees well with the experimental results.

Dynamic behaviors of viscous damper on concrete archaized building with lintel-column joint

  • Xue, Jianyang;Dong, Jinshuang;Sui, Yan
    • Earthquakes and Structures
    • /
    • 제13권4호
    • /
    • pp.409-419
    • /
    • 2017
  • In order to analyze the vibration control effect of viscous damper in the concrete archaized buildings with lintel-column joints under seismic action, 3 specimens were tested under dynamic excitation. Two specimens with viscous damper were defined as the controlled component and one specimen without viscous damper was specified as the non-controlled component. The loading process and failure patterns were obtained from the test results. The failure characteristics, skeleton curves and mechanical behavior such as the load-displacement hysteretic loops, load carrying capacity, degradation of strength and rigidity, ductility and energy dissipation of the joints were analyzed. The results indicate that the load-bearing capacity of the controlled component is significantly higher than that of the non-controlled component. The former component has an average increase of 27.4% in yield load and 22.4% in ultimate load, respectively. Meanwhile, the performance of displacement ductility and the ability of energy dissipation for the controlled component are superior to those of the non-controlled component as well. Compared with non-controlled component, equivalent viscous damping coefficients are improved by 27.3%-30.8%, the average increase is 29.0% at ultimate load for controlled component. All these results reflect that the seismic performance of the controlled component is significantly better than that of the non-controlled component. These researches are helpful for practical application of viscous damper in the concrete archaizing buildings with lintel-column joints.

변형지배거동을 하는 철근콘크리트 벽체의 에너지소산계수에 영향을 미치는 변수에 관한 연구 (Study on Factors Affecting on Energy Dissipation Coefficient of Reinforced Concrete Wall with Deformation-Dominated Behavior)

  • 유석형;강대영
    • 한국구조물진단유지관리공학회 논문집
    • /
    • 제28권5호
    • /
    • pp.38-46
    • /
    • 2024
  • 국내인구 60%이상이 거주하고 있는 벽식구조 아파트는 지진시 취성적 거동을 하게된다. 따라서 최근 성능기반 내진설계시 비선형 동적해석을 위한 철근콘크리트(RC)벽체의 에너지소산계수의 선택은 매우 중요하다. RC벽체의 에너지소산능력에 영향을 주는 주요변수로는 축력비, 단부횡보강근 간격 및 형상비인 것으로 기존실험연구에서 보고하였다. 대한건축학회 및 한국콘크리트학회에서는 「철근콘크리트 건축구조물의 성능기반 내진설계를 위한 비선형해석모델, 2021」을 통해 각 RC부재의 집중소성힌지모델 및 에너지소산계수를 제안하였다. 에너지소산계수 제안식에는 앞서 언급된 축력비 및 단부횡보강근의 변수는 포함하지 않고 있으며, 형상비의 경우 전단지배거동을 고려함에도 휨소성모델에 적용되므로 해석모델에 따른 형상비의 효과를 검토할 필요가 있을 것으로 사료된다. 이에 기존실험연구, 비선형해석프로그램의 섬유요소모델을 활용한 비선형해석 및 지침서의 에너지소산계수 제안식을 비교함으로써 각 변수별 에너지소산계수에 미치는 영향을 분석하였다. 축력비가 커질수록 에너지소산계수는 작아졌으며 단부횡보강근의 간격이 줄어들수록 에너지소산계수는 증가하였다. 또한 형상비가 커질수록 에너지소산계수는 커지는 경향을 보였으며 형상비의 영향이 제일 큰 것으로 나타났다.

Flexural behavior of reinforced lightweight concrete beams under reversed cyclic loading

  • Chien, Li-Kai;Kuo, Yi-Hao;Huang, Chung-Ho;Chen, How-Ji;Cheng, Ping-Hu
    • Structural Engineering and Mechanics
    • /
    • 제52권3호
    • /
    • pp.559-572
    • /
    • 2014
  • This paper presents the results of an experimental investigation on the flexural behavior of doubly reinforced lightweight concrete (R.L.C.) beams tested under cyclic loading. A total of 20 beam specimens were tested. Test results are presented in terms of ductility index, the degradation of strength and stiffness, and energy dissipation. The flexural properties of R.L.C. beam were compared to those of normal concrete (R.C.) beams. Test results show that R.L.C. beam with low and medium concrete strength (20, 40MPa) performed displacement ductility similar to the R.C. beam. The ductility can be improved by enhancing the concrete strength or decreasing the tension reinforcement ratio. Using lightweight aggregate in concrete is advantageous to the dynamic stiffness of R.L.C. beam. Enhancement of concrete strength and increase of reinforcement ratio will lead to increase of the stiffness degradation of beam. The energy dissipation of R.L.C beam, similar to R.C. beam, increase with the increase of tension reinforcement ratio. The energy dissipation of unit load cycle for smaller tension reinforcement ratio is relatively less than that of beam with higher reinforcement ratio.

동적혼성 모델을 이용한 난류채널의 온도장 해석 (On the Large Eddy Simulation of Temperature Field Using Dynamic Mixed Model in a Turbulent Channel)

  • 이건호;나양
    • 대한기계학회논문집B
    • /
    • 제28권10호
    • /
    • pp.1255-1263
    • /
    • 2004
  • An a priori test has been conducted for the dynamic mixed model which was generalized for the prediction of passive scalar field in a turbulent channel flow The results from a priori tests indicated that dynamic mixed model is capable of predicting both subgrid-scale heat flux and dissipation rather accurately. The success is attributed to the explicitly calculated resolved term incorporated into the model. The actual test of the model in a LES a posteriori showed that dynamic mixed model is superior to the widely used dynamic Smagorinsky model in the prediction of temperature statistics.

동적재료모델을 활용한 S355NL강의 열간 변형거동 분석 (Hot Deformation Behavior of S355NL Steel Based on Dynamic Material Model)

  • 이성호;박동준;송종한;이채훈;이진모;이태경
    • 소성∙가공
    • /
    • 제33권5호
    • /
    • pp.348-353
    • /
    • 2024
  • The S355NL steel has garnered attention as a structural material for applications in extremely challenging environments owing to its excellent mechanical properties. This study investigated the hot deformation behavior of S355NL steel through compression tests conducted in a temperature range of 900-1200℃ and a strain rate range of 10-3-1 s-1 to explore the optimal processing parameters. The flow behaviors consisted of an initial rapid increase and subsequent plateau with a marginal decrease in stress. This phenomenon was interpreted in terms of microstructural evolution, such as dislocation density and dynamic recrystallization. The efficiency of power dissipation and instability domains were derived using the dynamic material model based on the compression test dataset, providing a series of processing maps. In contrast to conventional processing maps plotted for a single strain value, this study has established ten maps at a strain interval of 0.1. This approach allowed for the consideration of continuously variable strain parameters, which is inherent to an actual metal-forming process. The efficiency of power dissipation was strongly governed by the high temperatures (≥ 1100℃). The strain rates barely affected the efficiency, but it primarily contributed to the instability domains. The application of high strain rates (≥ 10-1s-1) generated a region of negative instability due to the absence of dynamic recrystallization and the presence of cracks at grain boundaries.