• 제목, 요약, 키워드: analytical model

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Analytical Modeling for Reinforced Concrete Columns with Relaxed Section Details

  • Kim, Taewan;Chu, Yurim;Park, Hong-Gun
    • Architectural research
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    • v.19 no.3
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    • pp.79-87
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    • 2017
  • In earthquake engineering, dynamic analyses are usually conducted by using a nonlinear analytical model of the entire building in order to identify the performance against earthquakes. At the same time, a large number of dynamic analyses are required to consider uncertainties on analytical models and ground motions. Therefore, it is necessary for the analytical model to be adequate, that is to say, the runtime should not be too long as the entire building is modeled to be in much detail, or the nonlinear model should not yield outputs very far from the actual ones by excluding important behaviors too much. The analytical model is usually developed based on experimental results, which have been already conducted for reinforced concrete columns with relaxed details. Therefore, this study aimed at making analytical models to be able to simulate the hysteretic behavior of the columns simply and easily. The analytical model utilizes a lumped hinge model to represent nonlinear moment-rotation hysteretic behavior of RC columns, which is feasible for nonlinear dynamic analyses usually conducted in earthquake engineering and for matching the analytical model to test results. For the analytical model, elements and material models provided by OpenSees are utilized. The analytical model can define the envelope curve, pinching, and unloading stiffness deterioration, but shortcoming of this model is not to be able to consider axial force-moment interaction directly and to simulate strength deterioration after post-capping completely. However, the analytical model can still represent test results well by considering that the goal of this study is to propose a general way to represent the hysteretic behavior of RC columns with relaxed details, not to provide parameters for a refined hysteretic model that can be just applied case by case.

An analytical model for shear links in eccentrically braced frames

  • Ashtari, Amir;Erfani, Saeed
    • Steel and Composite Structures
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    • v.22 no.3
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    • pp.627-645
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    • 2016
  • When an eccentrically braced frame (EBF) is subjected to severe earthquakes, the links experience inelastic deformations while beams outside of the link, braces and columns are designed to remain elastic. To perform reliable inelastic analyses of EBFs sufficient analytical model which can accurately predict the inelastic performance of the links is needed. It is said in the literature that available analytical models for shear links generally predict very well the maximum shear forces and deformations from experiments on shear links, but may underestimate the intermediary values. In this study it is shown that available analytical models do not predict very well the maximum shear forces and deformations too. In this study an analytical model which can accurately predict both maximum and intermediary values of shear force and deformation is proposed. The model parameters are established based on test results from several experiments on shear links. Comparison of available test results with the hysteresis curves obtained using the proposed analytical model established the accuracy of the model. The proposed model is recommended to be used to perform inelastic analyses of EBFs.

해안지하수개발 최적화수치모델과 해석해의 비교연구 (Comparison of a Groundwater Simulation-Optimization Numerical Model with the Analytical Solutions)

  • 시뢰;최뢰;이찬종;박남식
    • 한국수자원학회:학술대회논문집
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    • pp.905-908
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    • 2009
  • In the management of groundwater in coastal areas, saltwater intrusion associated with extensive groundwater pumping, is an important problem. The groundwater optimization model is an advanced method to study the aquifer and decide the optimal pumping rates or optimal well locations. Cheng and Park gave the analytical solutions to the optimization problems basing on Strack's analytical solution. However, the analytical solutions have some limitations of the property of aquifer, boundary conditions, and so on. A simulation-optimization numerical method presented in this study can deal with non-homogenous aquifers and various complex boundary conditions. This simulation-optimization model includes the sharp interface solution which solves the same governing equation with Strack's analytical solution, therefore, the freshwater head and saltwater thickness should be in the same conditions, that can lead to the comparable results in optimal pumping rates and optimal well locations for both of the solutions. It is noticed that the analytical solutions can only be applied on the infinite domain aquifer, while it is impossible to get a numerical model with infinite domain. To compare the numerical model with the analytical solutions, calculation of the equivalent boundary flux was planted into the numerical model so that the numerical model can have the same conditions in steady state with analytical solutions.

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An Improved Analytical Model for Predicting the Switching Performance of SiC MOSFETs

  • Liang, Mei;Zheng, Trillion Q.;Li, Yan
    • Journal of Power Electronics
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    • v.16 no.1
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    • pp.374-387
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    • 2016
  • This paper derives an improved analytical model to estimate switching loss and analyze the effects of parasitic elements on the switching performance of SiC MOSFETs. The proposed analytical model considers the parasitic inductances, the nonlinearity of the junction capacitances and the nonlinearity of the trans-conductance. The turn-on process and the turn-off process are illustrated in detail, and equivalent circuits are derived and solved for each switching transition. The proposed analytical model is more accurate and matches better with experimental results than other analytical models. Note that switching losses calculated based on experiments are imprecise, because the energy of the junction capacitances is not properly disposed. Finally, the proposed analytical model is utilized to account for the effects of parasitic elements on the switching performance of a SiC MOSFET, and the circuit design rules for high frequency circuits are given.

Analytical modeling of thin-walled box T-joints

  • Marur, Prabhakar R.
    • Structural Engineering and Mechanics
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    • v.32 no.3
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    • pp.447-457
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    • 2009
  • A general analytical method for computing the joint stiffness from the sectional properties of the members that form the joint is derived using Vlasov's thin-walled beam theory. The analytical model of box T-joint under out-of-plane loading is investigated and validated using shell finite element results and experimental data. The analytical model of the T-joint is implemented in a beam finite element model using a revolute joint element. The out-of-plane displacement computed using the beam-joint model is compared with the corresponding shell element model. The results show close correlation between the beam revolute joint model and shell element model.

해석적 방법에 의한 강섬유 보강 초고성능 콘크리트(UHPFRC) 휨부재의 강도 평가 (Strength Evaluation of UHPFRC Flexural Member by Analytical Method)

  • 박우진;황훈희
    • 한국안전학회지
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    • v.28 no.2
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    • pp.55-59
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    • 2013
  • The analytical model was constituted to evaluate the flexural strength of UHPFRC(ultra high performance fiber reinforced concrete) member. The analytical approach was attemped to study the effect of the joint and the result compared with the experimental study to verify the analytical model. The calculated value tends to underestimate about 23%~25% in comparison with the experimental result of the jointed test member because the bond stress between precast UHPFRC and cast-in-place UHPFRC surface is not considered in the analytical model. But in the case of the continuous test member, the analytical model provides reasonable results for the flexural strength of UHPFRC member.

간략하고 정확한 장방형 각형강관 가새부재 이력거동 예측 위한 해석모델 (Simple and Accurate Analytical Model for Predicting Cyclic Behavior of Rectangular Steel HSS Braces)

  • 한상환;성민수;마동준
    • 한국지진공학회논문집
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    • v.21 no.3
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    • pp.145-152
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    • 2017
  • The objective of this study is to propose a simple and accurate analytical model for HSS braces. For this purpose, a physical theory model is adopted. Rectangular hollow section steel (HSS) braces are considered in this study. To accurately simulate the cyclic behavior of braces using the physical theory model, empirical equations calculating constituent parameters are implemented on the analytical model, which were proposed in the companion paper. The constituent parameters are cyclic brace growth, cyclic buckling load, and the incidence of local buckling and fracture. The analytical model proposed in this study was verified by comparing actual and simulated cyclic curves of brace specimens. It is observed that the proposed model accurately simulates the cyclic behavior of the braces throughout whole response range.

Analytical Calculation for Predicting the Air Gap Flux Density in Surface-Mounted Permanent Magnet Synchronous Machine

  • Feng, Yan-li;Zhang, Cheng-ning
    • Journal of Electrical Engineering and Technology
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    • v.12 no.2
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    • pp.769-777
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    • 2017
  • The research of air gap flux density has a significant effect on predicting and optimizing the structure parameters of electrical machines. In the paper, the air gap coefficient, leakage flux factor and saturation coefficient are first analytically expressed in terms of motor properties and structure parameters. Subsequently, the analytical model of average air gap flux density for surface-mounted permanent magnet synchronous machines is proposed with considering slotting effect and saturation. In order to verify the accuracy of the proposed analytical model, the experiment and finite element analysis (FEA) are used. It shows that the analytical results keep consistency well with the experimental result and FEA results, and the errors between FEA results and analytical results are less than 5% for SPM with high power. Finally, the analytical model is applied to optimizing the motor structure parameters. The optimal results indicate that the analytical calculation model provides a great potential to the machine design and optimization.

박판성형시 컬 예측모델 개발(I)-해석적 모델 (Development of Prediction Model for Sidewall Curl in Sheet Metal Forming(I)-Analytical Model)

  • 주병돈;박현규;김동우;문영훈
    • 소성가공
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    • v.16 no.6
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    • pp.432-437
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    • 2007
  • Sidewall curl is the curvature that results from non-uniform through-thickness strain present in the sheet stamping process which involves material flow over a die radius. In order to understand and control sidewall curl for tight fit-up tolerances, an analytical model that can provide a reliable measure for the amount of curl would be very helpful. In this study, a model is developed based on the moment-curvature relationship during bending-under-tension operations. The analytical model includes the variables of applied tensile force, the yield strength, the elastic modulus, the bending radius, and the sheet thickness, which are the primary factors affecting sidewall curl during sheet stamping operations. For the accuracy of analytical model, six possible deformation patterns are proposed on the basis of material properties and bending geometries.

Foundation Fieldbus에서 긴급데이터의 지연시간 성능해석 및 실험적 검증 (Delay Analysis of Urgent Data in the Foundation Fieldbus and Experimental Verification)

  • 홍승호;손병관
    • 제어로봇시스템학회논문지
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    • v.9 no.7
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    • pp.569-576
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    • 2003
  • The data link layer of Foundation Fieldbus provides both token-passing and scheduling services for periodic, time-critical and time-available data. This study developed an analytical model that evaluates the delay performance of urgent data when the data link layer of Foundation Fieldbus provides token-passing service. The validity of analytical model is verified using an experimental model that consists of network interface boards of Foundation Fieldbus. Comparison of analytical and experimental models shows that the analytical model can be utilized in the approximate analysis of the delay characteristics of time-critical data in the Foundation Fieldbus. The analytical model can also be used in the basic design stage of Foundation Fieldbus network system.