1,720,991 research outputs found
SENSITIVITY ANALYSIS OF THE SEISMIC RESPONSE OF CAISSON-TYPE QUAY WALL CONSIDERING THE VARIATION IN SOIL PROPERTIES AND GEOMETRICAL NONLINEARITY
No full text地盤・構造物系の地震時被害を数値解析により推定する場合, 解析に必要な地盤物性は確定値として用いられることが多い. しかし, 地盤物性のばらつきを考慮すると, その設定には常に不確実性が伴うこととなる。本研究では, ケーソン式岸壁を対象に, 地震時挙動に及ぼす地盤物性値の影響を把握するため, 液状化層の地盤パラメータを変化させた感度解析を実施した. その結果, ケーソン下の置換砂における内部摩擦角の不確実性が, 地震後のケーソン天端の残留変形量のばらつきに最も寄与することがわかった. また, 微小変形解析では地盤物性のばらつきが地震時のケーソン変形量に及ぼす影響を過大に評価してしまう危険性があり, 大変形解析により幾何学的非線形性を適切に考慮することで, より合理的な耐震性能の評価が可能になることが明らかとなった.Past experience has shown that port structures are often susceptible to severe damage during major earthquakes. From field observation of 1995 Hyogo-ken Nambu earthquake, it is observed that the seismic behavior of port structures such as caisson-type quay walls shows significant variability due to the variation in soil properties. In this study, seismic response analyses using a two-dimensional FE mesh, representing a caisson-type quay wall located in Rokko Island, are performed to carry out the sensitivity analysis the seismic performance of the caisson-type quay wall. To investigate the effect of uncertainties of soil properties on the dynamic behavior of the quay wall, a tornado diagram is used. It has been found that the uncertainties in the friction angle of reclaimed soil contribute most to the variability of the residual displacement and inclined angle of the quay wall. In addition, a Monte Carlo simulation considering the variation in soil properties has revealed that taking into account the effect of geometrical nonlinearity by using a large deformation analysis makes it possible to rationally assess the seismic performance of port structures while infinitesimal deformation analyses can overestimate the effect of the variation in soil properties on the deformation of port structures during earthquakes
FINITE STRAIN FORMULATION OF ELASTIC BODY BASED ON MULTIPLE SHEAR MECHANISM CONSIDERING GEOMETRICAL NONLINEARITY
No full text応用力学論文集: Vol. 19本稿では, 元来は砂の力学モデルとして提案されたひずみ空間多重せん断モデルを参考に, 多重せん断機構の概念に基づく有限変形を考慮した新たな弾性体構成式を提案した. 提案モデルでは, 多重せん断機構を構成する仮想的な各単純せん断機構（仮想単純せん断応力と仮想単純せん断ひずみの関係）に対して, 線形もしくはひずみ軟化を考慮した非線形関係を与えている. また, 大変形現象に伴う幾何学的非線形性を考慮できるよう, 有限変形理論における物質表示と空間表示の双方による定式化がなされている. 提案モデルの妥当性を検証するため, ゴム材料の引張試験（単純せん断および純せん断）を対象にシミュレーションを行ったところ, モデルパラメータとしてせん断弾性係数と仮想単純せん断機構におけるせん断強度（もしくは参照ひずみ）の2つを適切に調整することで, 試験結果を概ね再現できることがわかった.A new formulation of elastic body is proposed based on the concept of multiple shear mechanism referring to a strain space multiple shear mechanism model for geomaterials such as sands. In the proposed model, the relationship between the virtual simple shear strain and the virtual simple shear stress in the multiple shear mechanism is assumed to be linear or nonlinear considering the effect of strain softening. In addition, the formulation is written by both the material and spatial description based on the finite strain theory in order to consider the geometrical nonlinearity due to large deformation and rotation. Comparison between experiments for rubber materials under simple or pure shear condition and its simulation results demonstrates the capability of the proposed model even though only two model parameters (i.e., shear modulus of rigidity and shear strength in the virtual simple shear mechanism) are required to be specified
Revisit of the Formulation of Elastic Body Considering Inherent Anisotropy Based on the Concept of Multiple Shear Mechanism
Get PDFThe formulation of an elastic body, which can take the effect of inherent anisotropy into account, has been proposed by various researchers in 1970’s and widely used for the simulation of fibrous materials (e.g. lumber), materials containing reinforcement member in a certain direction, and blood vessel walls. This manuscript reinterprets the conventional formulation based on the concept of multiple shear mechanism, which has been applied to the modelling of granular materials (e.g. sands) and extended in order to consider the effect of inherent anisotropy of the materials.The formulation of an elastic body, which can take the effect of inherent anisotropy into account, has been proposed by various researchers in 1970’s and widely used for the simulation of fibrous materials (e.g. lumber), materials containing reinforcement member in a certain direction, and blood vessel walls. This manuscript reinterprets the conventional formulation based on the concept of multiple shear mechanism, which has been applied to the modelling of granular materials (e.g. sands) and extended in order to consider the effect of inherent anisotropy of the materials
Modeling of Clay through Strain Space Multiple Mechanism Model
Get PDFThe strain space multiple mechanism model, originally developed for cyclic behavior of granular materials such as sand, is adapted for idealizing stress strain behavior of clay under monotonic and cyclic loads. The proposed model has advantages over the conventional elasto-plastic models of Cam-clay type in the facts that (1) arbitrary initial K0 state can be analyzed by static gravity analysis, (2) stress induced anisotropy (i.e. effect of initial shear) in the steady (critical) state can be analyzed based on Shibata’s dilatancy model (1963), (3) over-consolidated clay can be analyzed by defining the dilatancy at the steady state based on over-consolidation ratio, (4) strain rate effects for monotonic and cyclic shear can be analyzed based on Isotach model proposed by Tatsuoka et al (2002) in the strain rate ranging from zero to infinity in addition to the conventional strain rate effects of secondary consolidation (creep) type. Performance of the proposed model is demonstrated through simulation of drained/undrained behavior of clay under monotonic and cyclic loading.The strain space multiple mechanism model, originally developed for cyclic behavior of granular materials such as sand, is adapted for idealizing stress strain behavior of clay under monotonic and cyclic loads. The proposed model has advantages over the conventional elasto-plastic models of Cam-clay type in the facts that (1) arbitrary initial K0 state can be analyzed by static gravity analysis, (2) stress induced anisotropy (i.e. effect of initial shear) in the steady (critical) state can be analyzed based on Shibata’s dilatancy model (1963), (3) over-consolidated clay can be analyzed by defining the dilatancy at the steady state based on over-consolidation ratio, (4) strain rate effects for monotonic and cyclic shear can be analyzed based on Isotach model proposed by Tatsuoka et al (2002) in the strain rate ranging from zero to infinity in addition to the conventional strain rate effects of secondary consolidation (creep) type. Performance of the proposed model is demonstrated through simulation of drained/undrained behavior of clay under monotonic and cyclic loading
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Model Tests and Numerical Simulations of Liquefaction and Lateral Spreading II
No full textThis open access book presents work collected through the Liquefaction Experiments and Analysis Projects (LEAP) in 2019 (LEAP-ASIA-2019) following the LEAP-UCD-2017 whose results have been published as a first volume. In addition to the research targets set in the previous one, such as the repeatability, variability, and sensitivity of lateral spreading on mildly sloping liquefiable sand, this volume includes research efforts to validate the generalized scaling law (hereafter “GSL”) for the identical prototype with the one employed in UCD-2017. In LEAP-ASIA-2019, 10 institutes around the world conducted 23 tests in total. It was the first multi-institutional attempts to investigate the validity of the generalized scaling law for the saturated sandy sloping deposit with wide range of initial conditions. The experimental data provided a unique basis for assessing the capabilities of six different simulation platforms for numerical simulation of soil liquefaction. The results of the experiments and the numerical simulations are presented and discussed in papers submitted by the project participants
Large Deformation Formulation Based on the Total Lagrange Method for a Nonlinear Elastic Body within a Framework of Multiple Shear Mechanism Accounting for Inherent Anisotropy
Get PDFA constitutive equation for a nonlinear elastic body within a framework of multiple shear mechanisms has been proposed to consider the geometrical nonlinearity based on large deformation (or finite strain) theory. However, the model could not take into account the effect of inherent anisotropy. This manuscript presents a formulation of a nonlinear elastic body that can consider the inherent anisotropy effect as well as the geometrical nonlinearity using the total Lagrange method in the large deformation theory
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Large Deformation Formulation Based on the Updated Lagrange Method for a Nonlinear Elastic Body within a Framework of Multiple Shear Mechanism Accounting for Inherent Anisotropy
Get PDFA constitutive model for a nonlinear elastic body within a framework of multiple shear mechanisms has been proposed to consider the geometrical nonlinearity based on large deformation (or finite strain) theory. The constitutive model has been extended to incorporate the effect of inherent anisotropy based on the total Lagrange method in the large deformation theory. This manuscript presents a formulation based on the updated Lagrange method to complete the description of a nonlinear elastic body model that can consider the inherent anisotropy effect as well as the geometrical nonlinearity
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