Insight into centrifuge modelling errors in predicting embedment depths of dynamically installed anchors

2020 ◽  
Vol 57 (11) ◽  
pp. 1796-1804
Author(s):  
Jiang Tao Yi ◽  
Ming Yang Cao ◽  
Yong Liu ◽  
Lei Zhang
Keyword(s):  
Strain Rate ◽  
Embedment Depth ◽  
Centrifuge Modelling ◽  
Significant Discrepancy ◽  
Centrifuge Model ◽  
Centrifuge Tests ◽  
Calculation Results ◽  
Strength And Stiffness ◽  
Insight Into ◽  
Modelling Error

In centrifuge modelling of dynamic events, a common practice is to preserve the inertial effect. This will lead to a loss of similitude in the strain rate between model and prototype. For centrifuge tests of dynamic installation of anchors, such strain rate dissimilarity may give rise to significant discrepancy in the anchor embedment depth between the model and the prototype, i.e., modelling error. Large-deformation finite element analyses that simulate both the model and the prototype were undertaken in this study to provide insight into this phenomenon. The calculation results revealed that the centrifuge model tends to underpredict the anchor embedment depth of the prototype. A parametric study of the influence of anchor geometry and weight, soil strength and stiffness, strain softening and rate parameters, and centrifuge acceleration level was subsequently conducted. It was found that such underprediction depends heavily upon the strain rate parameter. Based on analyses results, practical advices were given for centrifuge modellers to minimize the modelling error. The results presented and advices given in this study may facilitate the design of centrifuge model tests especially when the anchor embedment depth is an essential detail to be replicated in these tests.

Assessing the penetration resistance acting on a dynamically installed anchor in normally consolidated and overconsolidated clay

2017 ◽  
Vol 54 (1) ◽  
pp. 1-17 ◽  
Author(s):  
C. O’Beirne ◽  
C.D. O’Loughlin ◽  
C. Gaudin
Keyword(s):  
Strain Rate ◽  
Frictional Resistance ◽  
Embedment Depth ◽  
Rate Dependency ◽  
Mems Accelerometer ◽  
Rate Dependent ◽  
Centrifuge Tests ◽  
Shearing Resistance ◽  
Soil Interface ◽  
Overconsolidated Clay

Predicting the final embedment depth of a dynamically installed anchor is a key prerequisite for reliable calculation of anchor capacity. This paper investigates the embedment characteristics of dynamically installed anchors in normally consolidated and overconsolidated clay through a series of centrifuge tests involving a model anchor instrumented with a microelectric mechanical system (MEMS) accelerometer, enabling the full motion response of the anchor to be established. The data are used to assess the performance of an anchor embedment model based on strain-rate-dependent shearing resistance and fluid mechanics drag resistance. Predictions of a database of over 100 anchor installations — formed from this study and the literature — result in calculated anchor embedment depths that are within ±15% of the measurements. An interesting aspect, consistent across the entire database, relates to the strain rate dependence on frictional resistance relative to bearing resistance. The predictions reveal that strain rate dependency may indeed be higher for frictional resistance, although only if a soil strength lower than the fully remoulded strength is considered as the reference strength, which suggests that water may be entrained along a boundary layer at the anchor–soil interface during installation.

Advanced Approaches for Coupled Deformation-Seepage-Analyses of Suction Caisson Installation

2017 ◽  
Author(s):  
Marc Stapelfeldt ◽  
Britta Bienen ◽  
Jürgen Grabe
Keyword(s):  
Deformation Analysis ◽  
Numerical Techniques ◽  
Suction Caisson ◽  
Large Deformation Analysis ◽  
Centrifuge Tests ◽  
Calculation Results ◽  
Modelling Techniques ◽  
Explicit Solver ◽  
Excess Pore Pressures ◽  
Numerical Approaches

In this paper the installation procedure of suction caissons is investigated by means of coupled seepage large deformation analysis performed with finite element methods. The modelling techniques employed to enable simulations of the penetration of a caisson into the soil under offshore conditions, i. e. several tens of meters below the water level. The numerical model includes a u-p-formulation, which is used to calculate the excess pore pressures and effective stresses from the total stresses. The Coupled-Eulerian-Lagrangian (CEL) approach available in conjunction with the Abaqus/Explicit solver is used. The calculation results are compared to centrifuge tests that were carried out recently at the Centre for Offshore Foundation Systems (COFS). This sheds light on the potential and the limitations of the presented numerical techniques. This paper concludes with a brief discussion of alternative numerical approaches that could be capable of the simulation of caisson installation.

Senior consumers and risk/benefit trade-off in functional foods

2017 ◽  
Vol 119 (6) ◽  
pp. 1232-1246 ◽  
Author(s):  
Aina Ravoniarison
Keyword(s):  
Perceived Risk ◽  
Functional Foods ◽  
Perceived Value ◽  
Repurchase Intention ◽  
Significant Discrepancy ◽  
Trade Off ◽  
Content Type ◽  
Personal Variables ◽  
Practical Implications ◽  
Insight Into

Purpose The purpose of this paper is to examine how French senior consumers deal with duality between perceived risk and perceived value associated with functional foods (FFs) and to analyze whether the risk-value trade-off may help to derive different consumer profiles. Design/methodology/approach Data were collected from 220 senior consumers (50-70). A two-step clustering analysis was carried out on factor scores of perceived value and perceived risk. Discriminant analysis was then employed to verify the classification reliability, and analysis of variance was performed to profile the clusters on the basis of additional variables. Findings Four distinctive profiles of FF senior consumers were identified. Significant differences were found to be attributed to personality traits. Interestingly, the “Trustful enthusiasts” and the “Ambivalents” consumers do not differ in their repurchase intention, despite a significant discrepancy in risk perception. Practical implications The study is an opportunity to offer a segmentation of this attractive growing target of health-enhancing products. The typology can help the practitioners to find out a new valuable scope of messages to better communicate to elderly market. Originality/value The research seeks to contribute to the existing knowledge on seniors’ nutrition-related behavior, by proposing a segmentation still lacking in research works. Since FF perceived value appears to be multidimensional and not only utilitarian, the study provides a new insight into the experiential approach of health-enhancing eating. Also, it shows how the differences between FF consumers could be attributed to certain personal variables.

scholarly journals A Centrifuge Modelling and Finite Element Analysis of Laterally Loaded Single Piles in Sand with Focus on P–Y Curves

2020 ◽  
Author(s):  
Hocine Haouari ◽  
Ali Bouafia
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Hyperbolic Function ◽  
Contact Method ◽  
Centrifuge Modelling ◽  
Element Analysis ◽  
Soil Response ◽  
Dense Sand ◽  
Centrifuge Tests ◽  
Abaqus Software

Centrifuge modelling and finite element analysis are powerful tools of research on the lateral pile/soil interaction. This paper aims at presenting the main results of experimental and numerical analysis of the pile response under monotonic lateral loading in sand. After description of the experimental devices, it focuses on the determination of the load-transfer P-Y curves for rigid and semi-rigid piles embedded in dry dense sand by using the experimental bending moment profiles obtained in centrifuge tests, as well as by a three-dimensional finite element models using ABAQUS Software. The elastic perfectly plastic Mohr-Coulomb constitutive model has been used to describe the soil response, and the surface-to-surface contact method of ABAQUS software has been used to take into account the nonlinear response at soil/pile interface. The analysis methodology has allowed to propose a hyperbolic function as a model to construct P-Y curves for rigid and semi-rigid piles embedded in dry dense sand, this model is governed by two main parameters, which are the initial subgrade reaction modulus, and the lateral soil resistance, the latter has been formulated in terms of Rankine’s passive earth pressure coefficient, the sand dry unit weight, and the pile diameter.

Analysis of Uniaxial Dynamic Performance of Concrete-Filled Square Steel Tube Composite Column

2011 ◽  
Vol 94-96 ◽  
pp. 220-224 ◽  
Author(s):  
Xi Guang Cui ◽  
Hai Dong Xu
Keyword(s):  
Strain Rate ◽  
Bearing Capacity ◽  
Dynamic Performance ◽  
Concrete Strength ◽  
Steel Tube ◽  
Ultimate Bearing Capacity ◽  
Element Analysis ◽  
Compression Performance ◽  
Calculation Results ◽  
Square Steel Tube

Considering the strain rate then puts forward the modified uniaxial dynamic constitutive model related to strain rate in concrete-filled square steel tube and the modified calculation results match well with the experimental results. Based on the above conclusion, uniaxial compression performance finite element analysis with different strain rate among 10-5/s–10-3/s is completed, the results showed that strain rate can obviously change the dynamic performance of the concrete-filled square steel tube. Through the analysis of the influencing factors of the core concrete compressive strength, it is showed that with the increasing of the strain rate and the improving of concrete strength, the ultimate bearing capacity of concrete-filled square steel tube is higher and the ductility is reduced. With the increasing of stirrup ratio, ultimate bearing capacity is greater and the ductility is enhanced. With the sectional dimensions increasing, the ultimate bearing capacity is greater and the ductility is enhanced.

Constitutive Model of Supper-Alloy IN625 Based on Extrusion Test

2011 ◽  
Vol 314-316 ◽  
pp. 819-822 ◽  
Author(s):  
Zhong Tang Wang ◽  
Shi Hong Zhang ◽  
Ming Cheng ◽  
De Fu Li
Keyword(s):  
Constitutive Model ◽  
Strain Rate ◽  
Test Data ◽  
Arrhenius Equation ◽  
New Method ◽  
Extrusion Speed ◽  
Material Constitutive Model ◽  
Model Based ◽  
Calculation Results ◽  
Relative Errors

Abstract: It had been put forward that a new method to establish material constitutive model based on extrusion test, which was that the material constitutive model was determined with the Arrhenius equation according to the extrusion test data. The tube extruding test of supper-alloy Inconel625(IN625) had been done on 16300kN extrusion machine. According to the extrusion test data and the Arrhenius equation, it had been determined that the constitutive model of supper-alloy IN625 based on extrusion test, and the relative errors between calculation results of the model and experiment results are less than 7.8%. The suitable conditions of the constitutive model of supper-alloy IN625 are that the temperature being 1150°C～1200°C, and extrusion speed being 15～60mm/s, and strain-rate being 1.86～7.44.

Horizontal Capacity of Embedded Suction Anchors in Clay

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
S. Bang ◽  
K. Jones ◽  
Y. S. Kim ◽  
Y. Cho
Keyword(s):  
Analytical Solution ◽  
Model Test ◽  
Soil Type ◽  
Embedment Depth ◽  
Centrifuge Model Test ◽  
Test Results ◽  
Pullout Capacity ◽  
Direct Function ◽  
Centrifuge Model ◽  
Factors Influencing

The embedded suction anchor (ESA) is a type of permanent offshore foundation that is installed by a suction pile. The primary factors influencing the horizontal pullout capacity of an ESA include the loading point, the soil type, the embedment depth, and the addition of flanges. The main purpose of this study is to develop an analytical solution that is capable of estimating the horizontal pullout capacity of ESAs with the loading point being anywhere along its length with or without flanges. An analytical solution has been developed to estimate the horizontal pullout capacity of embedded suction anchors in clay seafloor. Validation has been made through comparisons with the centrifuge model test results. Results indicate that the horizontal pullout capacity of the embedded suction anchor in clay increases, reaches its peak, and then starts to decrease as the point of the load application moves downward. The effect of flanges on the horizontal pullout capacity is also found to be significant. The horizontal pullout capacity is a direct function of the loading point. The horizontal pullout capacity increases as the loading point moves downward and the maximum pullout capacity is obtained when the loading point is approximately at the mid-depth. The increase in horizontal pullout capacity can be significant, i.e., more than twice in magnitude when the maximum pullout capacity is compared with that associated with the loading point near the top or tip.

scholarly journals GPS determination of the velocity and strain-rate fields on Schirmacher Glacier, central Dronning Maud Land, Antarctica

2007 ◽  
Vol 53 (183) ◽  
pp. 558-564 ◽  
Author(s):  
P.S. Sunil ◽  
C.D. Reddy ◽  
M. Ponraj ◽  
Ajay Dhar ◽  
D. Jayapaul
Keyword(s):  
Strain Rate ◽  
Austral Summer ◽  
Base Station ◽  
Spatially Correlated ◽  
The North ◽  
Schirmacher Oasis ◽  
Global Positioning ◽  
Dronning Maud Land ◽  
Insight Into

Global positioning system (GPS) campaigns were conducted during the 2003 and 2004 austral summer seasons to obtain insight into the velocity and strain-rate distribution on Schirmacher Glacier, central Dronning Maud Land, East Antarctica. GPS data were collected at 21 sites and analyzed to estimate the site coordinates, baselines and velocities. The short-term precision of the base station, MAIT, is estimated from the daily coordinate repeatability solutions during the two years. All GPS points on the glacier were constrained with respect to MAIT and nearby International GPS Service stations. Horizontal velocities of the glacier sites lie between 1.89 ± 0.01 and 10.88 ± 0.01 ma−1 to the north-northeast, with an average velocity of 6.21 ± 0.01 m a−1. The principal strain rates provide a quantitative measurement of extension rates, which range from (0.11 ± 0.01) × 10−3 to (1.48 ± 0.85) × 10−3a−1, and shortening rates, which range from (0.04 ± 0.02) × 10−3 to (0.96 ± 0.16) × 10−3a−1. The velocity and strain-rate distributions across the GPS network in Schirmacher Glacier are spatially correlated with topography, subsurface undulations, fracture zones/crevasses and the partial blockage of the flow by nunataks and the Schirmacher Oasis.

scholarly journals Award winning first Hungarian active house refurbishment

2020 ◽  
Vol 15 (2) ◽  
pp. 233-244
Author(s):  
Kristóf Roland Horváth ◽  
István Kistelegdi
Keyword(s):  
Energy Performance ◽  
Building Envelope ◽  
Interior Space ◽  
Building Shape ◽  
Award Winning ◽  
Space Organization ◽  
Final Design ◽  
Calculation Results ◽  
Thermal Simulations ◽  
Insight Into

Abstract:First Hungarian Active House refurbishment won the Active House Award and the Energy Globe Hungary prize in 2017. This paper provides insight into the renewal design process of the typical home from the 70’s under disadvantageous site conditions. Dynamic thermal simulations helped to gain insight into space organization and building envelope concepts and their effects on comfort and energy performance. The Active House Standard was applied to evaluate the calculation results. The most advantageous concept was selected for final design elaboration and construction. The implemented building proved that in the refurbishment process it is possible to achieve highest level of efficiency in operation energy consumption with positive yearly balance by simultaneously being able to rearrange the complete interior space and as a consequence the building shape and envelope into a competitive design at international level.

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