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Jiro Fukui - One of the best experts on this subject based on the ideXlab platform.

  • effects of stress dilatancy behavior of soil on load transfer hysteresis in soil pile interaction
    Soils and Foundations, 2006
    Co-Authors: Masahiro Shirato, Junichi Koseki, Jiro Fukui, Yoshitomi Kimura
    Abstract:

    This paper examines the nonlinear hysteretic characteristics of load transfer between soil and piles for random Loading. First, we demonstrate that in past experiments the mobilized lateral soil resistance to piles varies with cyclic Loading Patterns. The soil resistance mobilized against one-sided cyclic Loading is smaller than that mobilized against fully-reversed cyclic Loading. We then establish that the stress-dilatancy behavior of soil causes such a Loading Pattern dependency, based on the mechanical property of soil elements subjected to cyclic compression-extension deformation. Finally, the hysteretic characteristics of load transfer between soil and pile associated with the stress-dilatancy effect is modeled as a function of cyclic Loading Pattern.

  • a new nonlinear hysteretic rule for winkler type soil pile interaction springs that considers Loading Pattern dependency
    Soils and Foundations, 2006
    Co-Authors: Masahiro Shirato, Junichi Koseki, Jiro Fukui
    Abstract:

    ABSTRACT We propose a new hysteretic rule for p-y curves to be used in the dynamic analysis of deep foundations. We first examine the results of past lateral cyclic pile load experiments to clarify the characteristics that are to be modeled in the load transfer hystereses in p-y curves. We then undertake an analytical study of soil element behavior when subject to cyclic passive (compressive) and active (extensile) deformation. We found that the soil resistance intensity to piles varies with different cyclic Loading Patterns, as the stress-dilatancy behavior in soil varies with cyclic Loading Patterns. We developed a new hysteretic rule that satisfies the observed dominant characteristics. Although the proposed hysteretic rule has its background in the peak-oriented rule, it is further extended to be a function of the Loading Pattern. Numerical tests using the proposed model showed that the model is capable of reproducing observed differences in the behavior of piles subjected to fully-reversed cyclic Loading and one-sided cyclic Loading, even though the typical peak-oriented rules are unable to predict these outcomes.

Masahiro Shirato - One of the best experts on this subject based on the ideXlab platform.

  • effects of stress dilatancy behavior of soil on load transfer hysteresis in soil pile interaction
    Soils and Foundations, 2006
    Co-Authors: Masahiro Shirato, Junichi Koseki, Jiro Fukui, Yoshitomi Kimura
    Abstract:

    This paper examines the nonlinear hysteretic characteristics of load transfer between soil and piles for random Loading. First, we demonstrate that in past experiments the mobilized lateral soil resistance to piles varies with cyclic Loading Patterns. The soil resistance mobilized against one-sided cyclic Loading is smaller than that mobilized against fully-reversed cyclic Loading. We then establish that the stress-dilatancy behavior of soil causes such a Loading Pattern dependency, based on the mechanical property of soil elements subjected to cyclic compression-extension deformation. Finally, the hysteretic characteristics of load transfer between soil and pile associated with the stress-dilatancy effect is modeled as a function of cyclic Loading Pattern.

  • a new nonlinear hysteretic rule for winkler type soil pile interaction springs that considers Loading Pattern dependency
    Soils and Foundations, 2006
    Co-Authors: Masahiro Shirato, Junichi Koseki, Jiro Fukui
    Abstract:

    ABSTRACT We propose a new hysteretic rule for p-y curves to be used in the dynamic analysis of deep foundations. We first examine the results of past lateral cyclic pile load experiments to clarify the characteristics that are to be modeled in the load transfer hystereses in p-y curves. We then undertake an analytical study of soil element behavior when subject to cyclic passive (compressive) and active (extensile) deformation. We found that the soil resistance intensity to piles varies with different cyclic Loading Patterns, as the stress-dilatancy behavior in soil varies with cyclic Loading Patterns. We developed a new hysteretic rule that satisfies the observed dominant characteristics. Although the proposed hysteretic rule has its background in the peak-oriented rule, it is further extended to be a function of the Loading Pattern. Numerical tests using the proposed model showed that the model is capable of reproducing observed differences in the behavior of piles subjected to fully-reversed cyclic Loading and one-sided cyclic Loading, even though the typical peak-oriented rules are unable to predict these outcomes.

Yoshitomi Kimura - One of the best experts on this subject based on the ideXlab platform.

  • effects of stress dilatancy behavior of soil on load transfer hysteresis in soil pile interaction
    Soils and Foundations, 2006
    Co-Authors: Masahiro Shirato, Junichi Koseki, Jiro Fukui, Yoshitomi Kimura
    Abstract:

    This paper examines the nonlinear hysteretic characteristics of load transfer between soil and piles for random Loading. First, we demonstrate that in past experiments the mobilized lateral soil resistance to piles varies with cyclic Loading Patterns. The soil resistance mobilized against one-sided cyclic Loading is smaller than that mobilized against fully-reversed cyclic Loading. We then establish that the stress-dilatancy behavior of soil causes such a Loading Pattern dependency, based on the mechanical property of soil elements subjected to cyclic compression-extension deformation. Finally, the hysteretic characteristics of load transfer between soil and pile associated with the stress-dilatancy effect is modeled as a function of cyclic Loading Pattern.

Junichi Koseki - One of the best experts on this subject based on the ideXlab platform.

  • effects of stress dilatancy behavior of soil on load transfer hysteresis in soil pile interaction
    Soils and Foundations, 2006
    Co-Authors: Masahiro Shirato, Junichi Koseki, Jiro Fukui, Yoshitomi Kimura
    Abstract:

    This paper examines the nonlinear hysteretic characteristics of load transfer between soil and piles for random Loading. First, we demonstrate that in past experiments the mobilized lateral soil resistance to piles varies with cyclic Loading Patterns. The soil resistance mobilized against one-sided cyclic Loading is smaller than that mobilized against fully-reversed cyclic Loading. We then establish that the stress-dilatancy behavior of soil causes such a Loading Pattern dependency, based on the mechanical property of soil elements subjected to cyclic compression-extension deformation. Finally, the hysteretic characteristics of load transfer between soil and pile associated with the stress-dilatancy effect is modeled as a function of cyclic Loading Pattern.

  • a new nonlinear hysteretic rule for winkler type soil pile interaction springs that considers Loading Pattern dependency
    Soils and Foundations, 2006
    Co-Authors: Masahiro Shirato, Junichi Koseki, Jiro Fukui
    Abstract:

    ABSTRACT We propose a new hysteretic rule for p-y curves to be used in the dynamic analysis of deep foundations. We first examine the results of past lateral cyclic pile load experiments to clarify the characteristics that are to be modeled in the load transfer hystereses in p-y curves. We then undertake an analytical study of soil element behavior when subject to cyclic passive (compressive) and active (extensile) deformation. We found that the soil resistance intensity to piles varies with different cyclic Loading Patterns, as the stress-dilatancy behavior in soil varies with cyclic Loading Patterns. We developed a new hysteretic rule that satisfies the observed dominant characteristics. Although the proposed hysteretic rule has its background in the peak-oriented rule, it is further extended to be a function of the Loading Pattern. Numerical tests using the proposed model showed that the model is capable of reproducing observed differences in the behavior of piles subjected to fully-reversed cyclic Loading and one-sided cyclic Loading, even though the typical peak-oriented rules are unable to predict these outcomes.

Akio Yamamoto - One of the best experts on this subject based on the ideXlab platform.

  • Loading Pattern optimization for a pwr using multi swarm moth flame optimization method with predator
    Journal of Nuclear Science and Technology, 2020
    Co-Authors: Satomi Ishiguro, Tomohiro Endo, Akio Yamamoto
    Abstract:

    This paper aims to propose a new methodology for optimizing fuel Loading Pattern in a nuclear reactor which is important for its higher safety and economic efficiency. Previous researches have prop...

  • application of the robust design concept for fuel Loading Pattern
    Journal of Nuclear Science and Technology, 2011
    Co-Authors: Tomohiro Endo, Kazuma Ohori, Akio Yamamoto
    Abstract:

    Application of the robust design concept for fuel Loading Pattern design is proposed as a new approach to improve the prediction accuracy of core characteristics. The robust design is a design concept that establishes a resistant (robust) system for perturbations or noises, by properly setting design variables. In order to apply the concept of robust design to fuel Loading Pattern design, we focus on a theoretical approach based on the higher order perturbation method. This approach indicates that the eigenvalue separation is one of the effective indices to measure the robustness of a designed fuel Loading Pattern. In order to verify the effectiveness of the eigenvalue separation as an index of robustness, numerical analysis is carried out for typical 3-loop PWR cores, and we evaluated the correlation between the eigenvalue separation and the variation of relative assembly power due to the perturbation of the cross section. The numerical results show that the variation of relative power decreases as the e...

  • Application of neural network for Loading Pattern screening of in-core optimization calculations
    Nuclear Technology, 2003
    Co-Authors: Akio Yamamoto
    Abstract:

    In this paper, neural networks are used to predict core characteristics, and the predicted results are used to screen poor Loading Patterns in order to improve optimization efficiency. The radial peaking factor, cycle length, and maximum burnup through the cycle depletion calculations were evaluated by the neural network, and these core characteristics were used for screening. The screened Loading Patterns were evaluated by the core calculation code as ordinary in-core optimizations. The calculation results of the test problem indicated that the Loading Pattern screening using the neural network effectively improves the optimization results. Since the computation time for a cycle depletion calculation with the neural network is quite short, the computation load for the screening is negligible. Since the neural network is periodically retrained using the latest evaluation results of the core calculation code, its prediction accuracy is continuously improved during the optimization. The typical prediction accuracies of the radial peaking factor, cycle length, and maximum burnup in the latter part of the optimizations were 3 to 4%, 0.01 to 0.02 GWd/t, and 0.2 GWd/t, respectively, in the test problem. These accuracies are satisfactory for Loading Pattern screening.

  • Loading Pattern Optimizations in a Distributed Parallel Environment
    1999
    Co-Authors: Akio Yamamoto, Hiroshi Hashimoto
    Abstract:

    Some stochastic optimization methods are studied for Loading Pattern designs in a parallel-computing environment to reduce total computation time. Affinities of these optimization methods with a parallel environment are evaluated.

  • a quantitative comparison of Loading Pattern optimization methods for in core fuel management of pwr
    Journal of Nuclear Science and Technology, 1997
    Co-Authors: Akio Yamamoto
    Abstract:

    The performance of several Loading Pattern(LP) optimization methods was quantitatively compared through a benchmark problem of PWR LP optimization. The simulated annealing(SA) method, the genetic algorithms(GA) method, the direct search(DS) method based on assembly multiple shuffling and the binary exchange(BE) method based on fuel assembly binary exchange were investigated as candidates for the optimization techniques. Hybrid strategy which combined different optimization methods was newly proposed, and the performances of two different new hybrid methods, which combined DS with BE and GA with BE were examined. From the results of the LP optimization benchmark problem, the superiority and inferiority of each method were clarified. Furthermore, it was demonstrated that the GA+BE hybrid strategy performed best among these methods. By combining GA with BE, the weaknesses of these two methods were compensated for with each other and the optimization performance was improved significantly. Therefore, the GA+BE hybrid method is quite effective for the LP optimization problems of PWR.