Effect of the Drum Height on the Seismic Behaviour of a Free-Standing Multidrum Column

The results of a shake-table study on the effect of the drum height on the seismic behaviour and bearing capacity of small-scale free-standing multidrum columns are presented. Columns of equal height with one, three, and six drums through their height were considered for the case of their self-weight only and for the case with an additional weight on the top of the column. The columns were exposed to a horizontal base acceleration of three accelerograms by successively increasing the maximum acceleration to their failure. The characteristic displacements and accelerations of the column were measured. It was concluded that an increase in the number of blocks in the column can significantly increase or decrease its ultimate bearing capacity, depending on the type of the applied accelerogram. It is expected that the experimental database can be useful in the validation of nonlinear numerical models for the dynamic analysis of multidrum columns.

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Concept Design of Very Large Floating Structures and Laboratory-Scale Physical Modelling

Volume 1: Offshore Technology; Offshore Geotechnics ◽

10.1115/omae2019-96259 ◽

2019 ◽

Author(s):

Lorenzo Cappietti ◽

Irene Simonetti ◽

Ilaria Crema

Keyword(s):

Numerical Models ◽

Physical Modelling ◽

Building Blocks ◽

Small Scale ◽

World Population ◽

Concept Design ◽

Wave Loads ◽

Experimental Database ◽

Floating Structures ◽

Very Large Floating Structures

Abstract The use of Very Large Floating Structures, VLFS, may represent a strategic approach in order to cope with some of the future societal challenges arising from the impressive growth of the world population. In this article, the motivations of this perspective are briefly discussed, the main issues for the development of VLFS are summarized and a concept structural design based on building-blocks technology is proposed. A small-scale physical model was manufactured and tested in the wave-current flume of the Laboratory of Maritime Engineering, LABIMA, of the Florence University, Italy. The aim of this study is the assessment of the structural feasibility and the effectiveness of the proposed VLFS concept, in terms of resistance to wave loads and control of floating behavior. The experimental measurements provide a first contribution to the necessary knowledge, about load magnitudes and floating behavior, for sizing some of the key structural components. The results appear to support the feasibility of the system in terms of usage of structural materials, technical components and building technologies, available at present, that can withstand the measured loads. Moreover, the acquired experimental database is fundamental in order to validate numerical models, in the perspective of using also such tools as complementary methodology for further improvement of the knowledge of design issues.

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Remediation of suspended solids and turbidity by improved settling tank design in a small-scale, free-standing toilet system using recycled blackwater

Water and Environment Journal ◽

10.1111/wej.12369 ◽

2018 ◽

Vol 33 (1) ◽

pp. 61-66 ◽

Cited By ~ 8

Author(s):

Brian T. Hawkins ◽

Katelyn L. Sellgren ◽

Enzo Cellini ◽

Ethan J. D. Klem ◽

Tess Rogers ◽

...

Keyword(s):

Suspended Solids ◽

Settling Tank ◽

Small Scale ◽

Free Standing ◽

Scale Free ◽

Tank Design

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Longitudinal Shear Analysis of Composite Slabs with Prepressed Embossments

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1122.265 ◽

2015 ◽

Vol 1122 ◽

pp. 265-268

Author(s):

Josef Holomek ◽

Miroslav Bajer ◽

Martin Vild

Keyword(s):

Bearing Capacity ◽

Design Method ◽

Numerical Models ◽

Longitudinal Shear ◽

Small Scale ◽

Shear Tests ◽

Bending Tests ◽

Load Bearing ◽

Composite Slabs ◽

Shear Bearing Capacity

Composite slabs with prepressed embossments present an effective solution for horizontal load bearing structures. Sheeting serves as a formwork in construction stage and as a tension bearing member after hardening of concrete. There is no need for additional tensile reinforcement in case of sufficient longitudinal shear bearing capacity of the embossments. Longitudinal shear bearing capacity is not precisely determined when designing according to nowadays standards. Full scale bending tests of the slabs are used to determine characteristics for m – k method or partial connection method. Bending tests are expensive and space demanding. Alternatively small-scale shear tests can be used to determine shear characteristics of the sheeting. However, shear tests cannot include all the effects affecting the bearing capacity of bended slab, such as effect of curvature or distribution of load. Therefore, related design method has to be used to determine load bearing capacity of the slab in bending. This paper extends achievements presented by the authors in contribution in CRRB 2013. The results of small-scale tests are compared with results of numerical models of the slab in shear. Numerical models are created in two different finite element codes. Setting of steel-concrete interface properties in the models is validated using data from literature.

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The Effectiveness of Ensemble-Neural Network Techniques to Predict Peak Uplift Resistance of Buried Pipes in Reinforced Sand

Applied Sciences ◽

10.3390/app11030908 ◽

2021 ◽

Vol 11 (3) ◽

pp. 908

Author(s):

Jie Zeng ◽

Panagiotis G. Asteris ◽

Anna P. Mamou ◽

Ahmed Salih Mohammed ◽

Emmanuil A. Golias ◽

...

Keyword(s):

Neural Network ◽

Numerical Models ◽

Correlation Coefficients ◽

Network Models ◽

Small Scale ◽

Offshore Platforms ◽

Neural Network Models ◽

Buried Pipes ◽

Ensemble Techniques ◽

Uplift Resistance

Buried pipes are extensively used for oil transportation from offshore platforms. Under unfavorable loading combinations, the pipe’s uplift resistance may be exceeded, which may result in excessive deformations and significant disruptions. This paper presents findings from a series of small-scale tests performed on pipes buried in geogrid-reinforced sands, with the measured peak uplift resistance being used to calibrate advanced numerical models employing neural networks. Multilayer perceptron (MLP) and Radial Basis Function (RBF) primary structure types have been used to train two neural network models, which were then further developed using bagging and boosting ensemble techniques. Correlation coefficients in excess of 0.954 between the measured and predicted peak uplift resistance have been achieved. The results show that the design of pipelines can be significantly improved using the proposed novel, reliable and robust soft computing models.

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Experimental and numerical investigation on the thermal and mechanical behaviours of thermal barrier coatings exposed to CMAS corrosion

Journal of Advanced Ceramics ◽

10.1007/s40145-021-0457-2 ◽

2021 ◽

Author(s):

Dongxu Li ◽

Peng Jiang ◽

Renheng Gao ◽

Fan Sun ◽

Xiaochao Jin ◽

...

Keyword(s):

Reaction Layer ◽

Numerical Models ◽

Critical Factor ◽

Peak Stress ◽

Thermal Barrier ◽

Free Standing ◽

Barrier Coating ◽

Corrosion Model ◽

Mechanical Behaviours ◽

Alumino Silicate

AbstractCalcium-magnesium-alumino-silicate (CMAS) corrosion is a critical factor which causes the failure of thermal barrier coating (TBC). CMAS attack significantly alters the temperature and stress fields in TBC, resulting in their delamination or spallation. In this work, the evolution process of TBC prepared by suspension plasma spraying (SPS) under CMAS attack is investigated. The CMAS corrosion leads to the formation of the reaction layer and subsequent bending of TBC. Based on the observations, a corrosion model is proposed to describe the generation and evolution of the reaction layer and bending of TBC. Then, numerical simulations are performed to investigate the corrosion process of free-standing TBC and the complete TBC system under CMAS attack. The corrosion model constructs a bridge for connecting two numerical models. The results show that the CMAS corrosion has a significant influence on the stress field, such as the peak stress, whereas it has little influence on the steady-state temperature field. The peak of stress increases with holding time, which increases the risk of the rupture of TBC. The Mises stress increases nonlinearly along the thick direction of the reaction layer. Furthermore, in the traditional failure zone, such as the interface of the top coat and bond coat, the stress obviously changes during CMAS corrosion.

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Application of Artificial Neural Networks for Predicting the Bearing Capacity of Shallow Foundations on Rock Masses

Rock Mechanics and Rock Engineering ◽

10.1007/s00603-021-02549-1 ◽

2021 ◽

Author(s):

M. A. Millán ◽

R. Galindo ◽

A. Alencar

Keyword(s):

Bearing Capacity ◽

Analytical Solutions ◽

Shear Failure ◽

Numerical Models ◽

Computational Effort ◽

Shallow Foundations ◽

Geological Strength Index ◽

Rock Masses ◽

Ann Model ◽

Artificial Neural

AbstractCalculation of the bearing capacity of shallow foundations on rock masses is usually addressed either using empirical equations, analytical solutions, or numerical models. While the empirical laws are limited to the particular conditions and local geology of the data and the application of analytical solutions is complex and limited by its simplified assumptions, numerical models offer a reliable solution for the task but require more computational effort. This research presents an artificial neural network (ANN) solution to predict the bearing capacity due to general shear failure more simply and straightforwardly, obtained from FLAC numerical calculations based on the Hoek and Brown criterion, reproducing more realistic configurations than those offered by empirical or analytical solutions. The inputs included in the proposed ANN are rock type, uniaxial compressive strength, geological strength index, foundation width, dilatancy, bidimensional or axisymmetric problem, the roughness of the foundation-rock contact, and consideration or not of the self-weight of the rock mass. The predictions from the ANN model are in very good agreement with the numerical results, proving that it can be successfully employed to provide a very accurate assessment of the bearing capacity in a simpler and more accessible way than the existing methods.

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Observational aspects of prominence oscillations

Proceedings of the International Astronomical Union ◽

10.1017/s1743921308014816 ◽

2007 ◽

Vol 3 (S247) ◽

pp. 152-157 ◽

Cited By ~ 4

Author(s):

Oddbjørn Engvold

Keyword(s):

Magnetic Structure ◽

Numerical Models ◽

Small Scale ◽

Solar Prominences ◽

Scale Structures ◽

Oscillations And Waves ◽

Available Information ◽

Small Scale Structures

AbstractSeismology has become a powerful tool in studies of the magnetic structure of solar prominences and filaments. Reversely, analytical and numerical models are guided by available information about the spatial and thermodynamical structure of these enigmatic structures. The present invited paper reviews recent observational results on oscillations and waves as well as details about small-scale structures and dynamics of prominences and filaments.

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Coupled Thermo-Hydro-Geochemical Models of Engineered Barrier Systems: The Febex Project

MRS Proceedings ◽

10.1557/proc-663-561 ◽

2000 ◽

Vol 663 ◽

Cited By ~ 2

Author(s):

J. Samper ◽

R. Juncosa ◽

V. Navarro ◽

J. Delgado ◽

L. Montenegro ◽

...

Keyword(s):

Large Scale ◽

Reference Model ◽

Numerical Models ◽

Full Scale ◽

Small Scale ◽

Model Parameters ◽

In Situ Test ◽

Wide Range ◽

Engineered Barrier

ABSTRACTFEBEX (Full-scale Engineered Barrier EXperiment) is a demonstration and research project dealing with the bentonite engineered barrier designed for sealing and containment of waste in a high level radioactive waste repository (HLWR). It includes two main experiments: an situ full-scale test performed at Grimsel (GTS) and a mock-up test operating since February 1997 at CIEMAT facilities in Madrid (Spain) [1,2,3]. One of the objectives of FEBEX is the development and testing of conceptual and numerical models for the thermal, hydrodynamic, and geochemical (THG) processes expected to take place in engineered clay barriers. A significant improvement in coupled THG modeling of the clay barrier has been achieved both in terms of a better understanding of THG processes and more sophisticated THG computer codes. The ability of these models to reproduce the observed THG patterns in a wide range of THG conditions enhances the confidence in their prediction capabilities. Numerical THG models of heating and hydration experiments performed on small-scale lab cells provide excellent results for temperatures, water inflow and final water content in the cells [3]. Calculated concentrations at the end of the experiments reproduce most of the patterns of measured data. In general, the fit of concentrations of dissolved species is better than that of exchanged cations. These models were later used to simulate the evolution of the large-scale experiments (in situ and mock-up). Some thermo-hydrodynamic hypotheses and bentonite parameters were slightly revised during TH calibration of the mock-up test. The results of the reference model reproduce simultaneously the observed water inflows and bentonite temperatures and relative humidities. Although the model is highly sensitive to one-at-a-time variations in model parameters, the possibility of parameter combinations leading to similar fits cannot be precluded. The TH model of the “in situ” test is based on the same bentonite TH parameters and assumptions as for the “mock-up” test. Granite parameters were slightly modified during the calibration process in order to reproduce the observed thermal and hydrodynamic evolution. The reference model captures properly relative humidities and temperatures in the bentonite [3]. It also reproduces the observed spatial distribution of water pressures and temperatures in the granite. Once calibrated the TH aspects of the model, predictions of the THG evolution of both tests were performed. Data from the dismantling of the in situ test, which is planned for the summer of 2001, will provide a unique opportunity to test and validate current THG models of the EBS.

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Numerical models of slab migration in continental collision zones

Solid Earth ◽

10.5194/se-3-293-2012 ◽

2012 ◽

Vol 3 (2) ◽

pp. 293-306 ◽

Cited By ~ 38

Author(s):

V. Magni ◽

J. van Hunen ◽

F. Funiciello ◽

C. Faccenna

Keyword(s):

Subduction Zone ◽

Plate Tectonics ◽

Numerical Models ◽

Continental Collision ◽

Force Balance ◽

Small Scale ◽

Dip Angle ◽

External Forces ◽

Stress Dependent ◽

Subduction System

Abstract. Continental collision is an intrinsic feature of plate tectonics. The closure of an oceanic basin leads to the onset of subduction of buoyant continental material, which slows down and eventually stops the subduction process. In natural cases, evidence of advancing margins has been recognized in continental collision zones such as India-Eurasia and Arabia-Eurasia. We perform a parametric study of the geometrical and rheological influence on subduction dynamics during the subduction of continental lithosphere. In our 2-D numerical models of a free subduction system with temperature and stress-dependent rheology, the trench and the overriding plate move self-consistently as a function of the dynamics of the system (i.e. no external forces are imposed). This setup enables to study how continental subduction influences the trench migration. We found that in all models the slab starts to advance once the continent enters the subduction zone and continues to migrate until few million years after the ultimate slab detachment. Our results support the idea that the advancing mode is favoured and, in part, provided by the intrinsic force balance of continental collision. We suggest that the advance is first induced by the locking of the subduction zone and the subsequent steepening of the slab, and next by the sinking of the deepest oceanic part of the slab, during stretching and break-off of the slab. These processes are responsible for the migration of the subduction zone by triggering small-scale convection cells in the mantle that, in turn, drag the plates. The amount of advance ranges from 40 to 220 km and depends on the dip angle of the slab before the onset of collision.

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