Modelling creep deformation in floating ice

2003 ◽  
Vol 30 (1) ◽  
pp. 28-41 ◽  
Author(s):  
K van Steenis ◽  
F E Hicks ◽  
T M Hrudey ◽  
S Beltaos
Keyword(s):  
Large Scale ◽  
Field Experiments ◽  
Numerical Models ◽  
Ice Sheet ◽  
Transversely Isotropic ◽  
Element Model ◽  
Ice Cover ◽  
Load Test ◽  
Drilling Rig

The ability to predict the response of an ice sheet to long-term loading is important in many situations. In northern regions, ice sheets have been used as construction platforms, drilling rig platforms, airfields, parking lots, and festival platforms. Numerical models can be used to predict the deflection of an ice sheet over time and, together with a failure criterion based on allowable deflection, can facilitate the safe use of an ice cover under long-term loading situations. In this study, a two-dimensional axisymmetric finite element model was developed to model the behaviour of a homogeneous, transversely isotropic, infinite ice cover under long-term loading. The model was validated using 33 sets of long-term load test data from large-scale field experiments performed on lake, bay, and reservoir ice and was shown to be capable of reliably predicting deflections under a variety of loading scenarios.Key words: bearing capacity of ice, long-term loading, ice platforms.

scholarly journals Displacement Study of a Large-Scale Freeform Timber Plate Structure Using a Total Station and a Terrestrial Laser Scanner

Sensors ◽  
2020 ◽  
Vol 20 (2) ◽  
pp. 413 ◽  
Author(s):  
Anh Chi Nguyen ◽  
Yves Weinand
Keyword(s):  
Large Scale ◽  
Numerical Models ◽  
Laser Scanner ◽  
Experimental Tests ◽  
Point Clouds ◽  
Element Model ◽  
Experimental Investigations ◽  
Bottom Surface ◽  
Terrestrial Laser Scanner ◽  
Total Station

Recent advances in timber construction have led to the realization of complex timber plate structures assembled with wood-wood connections. Although advanced numerical modelling tools have been developed to perform their structural analysis, limited experimental tests have been carried out on large-scale structures. However, experimental investigations remain necessary to better understand their mechanical behaviour and assess the numerical models developed. In this paper, static loading tests performed on timber plate shells of about 25 m span are reported. Displacements were measured at 16 target positions on the structure using a total station and on its entire bottom surface using a terrestrial laser scanner. Both methods were compared to each other and to a finite element model in which the semi-rigidity of the connections was represented by springs. Total station measurements provided more consistent results than point clouds, which nonetheless allowed the visualization of displacement fields. Results predicted by the model were found to be in good agreement with the measurements compared to a rigid model. The semi-rigid behaviour of the connections was therefore proven to be crucial to precisely predict the behaviour of the structure. Furthermore, large variations were observed between as-built and designed geometries due to the accumulation of fabrication and construction tolerances.

scholarly journals Short- and Long-Term Effects of Nonconsciously Processed Ambient Scents in a Servicescape: Findings From Two Field Experiments

2019 ◽  
Vol 22 (4) ◽  
pp. 440-455 ◽  
Author(s):  
Anna Girard ◽  
Marcel Lichters ◽  
Marko Sarstedt ◽  
Dipayan Biswas
Keyword(s):  
Large Scale ◽  
Field Experiments ◽  
Field Studies ◽  
Long Term Effects ◽  
Short Term ◽  
Railway Company ◽  
Short And Long Term ◽  
Ambient Scents ◽  
Short Term Effects

Ambient scents are being increasingly used in different service environments. While there is emerging research on the effects of scents, almost nothing is known about the long-term effects of consumers’ repeated exposure to ambient scents in a service environment as prior studies on ambient scents have been lab or field studies examining short-term effects of scent exposure only. Addressing this limitation, we examine the short- and long-term effects of ambient scents. Specifically, we present a conceptual framework for the short- and long-term effects of nonconsciously processed ambient scent in olfactory-rich servicescapes. We empirically test this framework with the help of two large-scale field experiments, conducted in collaboration with a major German railway company, in which consumers were exposed to a pleasant, nonconsciously processed scent. The first experiment demonstrates ambient scent’s positive short-term effects on consumers’ service perceptions. The second experiment—a longitudinal study conducted over a 4-month period—examines scent’s long-term effects on consumers’ reactions and demonstrates that the effects persist even when the scent has been removed from the servicescape.

Long-term settlement of model rock-socketed piers

1989 ◽  
Vol 26 (3) ◽  
pp. 348-358 ◽  
Author(s):  
Robert G. Horvath ◽  
K-J. Chae
Keyword(s):  
Large Scale ◽  
Load Transfer ◽  
Creep Behaviour ◽  
Small Diameter ◽  
Soft Rock ◽  
Load Test ◽  
Creep Model ◽  
Secondary Creep ◽  
Initial Portion

Very little information is available concerning the long-term settlement behaviour of drilled pier foundations socketed into rock. This paper summarizes the results of laboratory investigations of the long-term settlement (creep) behaviour of model socketed pier foundations. The testing program included seven model piers constructed with different materials and different load-support conditions. The primary models were two small-diameter concrete piers constructed in soft shale. For all models tested the results indicated similarly shaped time–displacement curves, having two distinct regions. The initial portion of the curves represents a region of primary creep and the remaining portion represents a zone of secondary creep having a much lower rate of displacement. A comparison of short-term (1 day, which is a normal maximum duration of a full-scale load test) and long-term (200 days) settlements for the model piers showed an 84–245% increase in settlements. In addition, some information concerning load transfer with time in the model piers and available data from loading tests on large-scale socketed piers are included. Key words: socketed pier foundations, long-term settlement, creep model tests, soft rock.

scholarly journals MODELLING LONG TERM IMPLICATION OF CLIMATE CHANGE PROJECTION ON SHORE MORPHOLOGY OF NORTH NORFOLK, UK, COMBINING TOMAWAC AND SCAPE

2011 ◽  
Vol 1 (32) ◽  
pp. 61 ◽  
Author(s):  
Nicolas Chini ◽  
Peter Stansby ◽  
Mike Walkden ◽  
Jim Hall ◽  
Judith Wolf ◽  
...  
Keyword(s):  
Climate Change ◽  
Global Climate Change ◽  
Large Scale ◽  
Numerical Models ◽  
Global Climate ◽  
Stationary Processes ◽  
Climate Change Projections ◽  
Future Evolution ◽  
The Future

Assessment of nearshore response to climatic change is an important issue for coastal management. To predict potential effects of climate change, a framework of numerical models has been implemented which enables the downscaling of global projections to an eroding coastline, based on TOMAWAC for inshore wave propagation input into SCAPE for shoreline modelling. With this framework, components of which have already been calibrated and validated, a set of consistent global climate change projections is used to estimate the future evolution of an un-engineered coastline. The response of the shoreline is sensitive to the future scenarios, underlying the need for long term large scale offshore conditions to be included in the prediction of non-stationary processes.

Influence of river pattern and sediment input on estuary morphology

2020 ◽  
Author(s):  
Anne Baar ◽  
Elena Bastianon ◽  
Lisanne Braat ◽  
Daniel Parsons
Keyword(s):  
River Discharge ◽  
Large Scale ◽  
Numerical Models ◽  
Sediment Supply ◽  
Tidal Amplitude ◽  
Model Studies ◽  
Braiding Index ◽  
Sediment Input ◽  
River Pattern

<p>Alluvial estuaries are dynamic landscapes that are very sensitive to changes in boundary conditions such as river discharge and sediment supply. A better understanding of the influence of upstream river discharge and sediment input on the development of estuaries under various scenarios requires long-term morphodynamic models, to both predict future changes and improve geological interpretations by storing the stratigraphy. Past 1D model studies have shown that upstream river discharge has a significant effect on the equilibrium bed profile of estuaries, but these studies ignore the effect of 2D bar and channel formation. Using 2D numerical models to predict the development of these systems on the scale of millennia proved to be difficult, since the modelled morphology is very sensitive to the choice in e.g. sediment transport predictor and bed slope effect. In this study, we use the knowledge of previous research that determined best parameter settings for realistic river and bar patterns to model long-term and large-scale estuary morphodynamics in Delft3D. Our objective is to quantify the effects of river discharge and sediment supply on the shape of estuaries and its deposits. Firstly, we systematically varied upstream river width and tidal amplitude to examine the relation between upstream river pattern and estuary dimensions. We quantified e.g. braiding index, bar dimensions, and tidal excursion length. Results show that flood flow velocities and tidal prism are less influenced by river discharge than suggested by 1D models, and are significantly influenced by the braiding index of the river. With relatively high tides, estuary bar patterns depend on tidal amplitude, while with lower tides estuary depth and braiding index are related to upstream river width and discharge. Next steps will include varying discharge to study the effect on the rate of adaptation of the river and estuary, and varying the grain size of the sediment input at the upstream boundary. We will input coarse sediment to explore differences between fluvial deposits and tidal currents, and fine sediment to use the model for research related to biofilm.</p>

scholarly journals Optical properties of the ice cover on Vendyurskoe lake, Russian Karelia (1995–2012)

2013 ◽  
Vol 54 (62) ◽  
pp. 121-124 ◽  
Author(s):  
G. Zdorovennova ◽  
R. Zdorovennov ◽  
N. Palshin ◽  
A. Terzhevik
Keyword(s):  
Optical Properties ◽  
Solar Radiation ◽  
Ice Sheet ◽  
Ice Cover ◽  
Late Winter ◽  
Lake Ecosystem ◽  
Attenuation Coefficients ◽  
Quasi Newton ◽  
Northwestern Russia

AbstractSolar radiation penetrating the ice is one of the most important factors that determine the functioning of lake ecosystem in late winter. Parameterization of the attenuation of solar radiation in the snow-ice sheet is an essential tool in the study of the light regime of ice-covered lakes. The optical properties of the snow-ice sheet in Vendyurskoe lake, northwestern Russia, are investigated on the basis of long-term field observations (1995–2012). The four-layer approach (snow, white ice, slush and congelation ice) is used to study the attenuation of the downwelling planar irradiance in the snow-ice sheet. The bulk attenuation coefficients for four layers (18.8 m–1 for snow, 6 m−1 for white ice, 3.5 m−1 for slush and 2.1 m−1 for congelation ice) are calculated by the quasi-Newton method. A comparison of observed and calculated values of the irradiance beneath the ice shows that the determined coefficients adequately describe the attenuation of the downwelling irradiance by snow-ice cover.

Time-scales and degrees of freedom operating in the evolution of continental ice-sheets

1990 ◽  
Vol 81 (4) ◽  
pp. 371-384 ◽  
Author(s):  
Richard C. A. Hindmarsh
Keyword(s):  
Mass Balance ◽  
Degrees Of Freedom ◽  
Large Scale ◽  
Numerical Models ◽  
Perturbation Expansion ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Plane Flow ◽  
Surface Mass ◽  
Continental Ice Sheets

ABSTRACTComprehensible explanations of the operation of earth climate systems should consist of descriptions of the operation of a few degrees of freedoms. Qualitative interpretations of results from large-scale numerical models generally follow this principle, but do not render formal definitions of the precise nature of such degrees of freedom.At its simplest, ice-sheet kinematics requires knowledge of the evolving height and span. Rheology and surface mass-balance impose different requirements upon the co-evolution of these variables, meaning a two-degree of freedom model is over-prescribed. By means of a perturbation expansion about the analytic similarity solution for viscous spreading, eigenfunctions corresponding to degrees of freedom in the ice-sheet profile are obtained, and are used to decompose mass-balance distributions. Only a few eigenfunctions are needed to replicate numerical models, implying that ice-sheets in plane flow may operate with fewer than ten degrees of freedom.Unstable evolution of ice-sheets can occur, when the operation of a very large number of degrees of freedom can be manifested. Previous work is reviewed and new results for the unstable transformation of valley glaciers into ice-sheets are presented. Phasing of initiation may be an unpredictable phenomenon.

scholarly journals Structural analysis and improvement for a new form traveler in long-span cantilever-casting arch bridge

2021 ◽  
Vol 13 (4) ◽  
pp. 168781402110099
Author(s):  
Xiujun Li ◽  
Jianting Zhou ◽  
Yuexing Wu ◽  
Zhen Wang ◽  
Xiaogang Li
Keyword(s):  
Numerical Models ◽  
Great Influence ◽  
Element Model ◽  
Load Test ◽  
Stiffness Index ◽  
Analysis Model ◽  
Arch Bridge ◽  
New Form ◽  
Improvement Scheme ◽  
Strength And Stiffness

A form traveler used in bridge construction has a great influence on the safety of the performance and alignment of bridges. As a cantilever casting segment of a bridge becomes longer and heavier, the traditional form traveler may not meet the strength and stiffness requirements, and there is a risk of collapse. This study has devised a new triangle truss form traveler and investigated the performance based on the Ye-Lang Lake arch bridge in China. Firstly, the numerical models of the form traveler were established to get the strength and stiffness index of the form traveler used for the arch Segment 2. Subsequently, the improvement scheme of the mechanical properties of the form traveler has been proposed. Then the partial refined numerical analysis model of the C-type hook has been established, a finite element model, and a design scheme for improving partial structures of the C-type hook was proposed. Finally, the field load test was carried out to verify the reliability of the new form traveler. The test results show that the improvement of the new form traveler is effective.

Characterisation of the Shear Stud-Concrete Connection Using Finite Element Analysis

2014 ◽  
Vol 553 ◽  
pp. 570-575
Author(s):  
Daniel John Lowe ◽  
Raj Das ◽  
George Charles Clifton ◽  
Namasivayam Navaranjan
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Large Scale ◽  
Numerical Models ◽  
Experimental Testing ◽  
Element Model ◽  
Cement Matrix ◽  
Element Analysis ◽  
Mesoscopic Model ◽  
Concrete Interface

The degradation of the connection between shear studs and concrete is a complicated phenomenon that depends on many factors, including; interfacial properties, concrete crushing and steel yielding. The purpose of this paper is to outline the scope and methodology of the research project being undertaken to characterise the shear stud-concrete interface of a composite beam using finite element analysis. A mesoscopic model will be created for a section of the interface. With the use of a multi-scale approach, the mesoscopic model will be incorporated into a global model. The influence of steel roughness and mechanical properties will be included. Concrete is to be modelled as heterogeneous, comprising discrete regions of aggregate, cement matrix, and an interfacial transition zone (ITZ). The effect of the ITZ will be taken into account using a zero thickness cohesive element. Experimental testing using a push-up rig is to be conducted to verify the numerical models. The ultimate aim is to develop a simplified representation of the shear stud-concrete interface that can be used in a large scale finite element model of a composite member to correctly capture the behaviour of the shear stud-concrete interface in the elastic and inelastic state.

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