Assessment of Flexure Failure Models Using Loads Measured on the Conical Piers of the Confederation Bridge During 1998–2008

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Chee K. Wong ◽  
Thomas G. Brown ◽  
J. Susan Robertson
Keyword(s):  
Prince Edward Island ◽  
Monitoring Program ◽  
Physical And Mechanical Properties ◽  
Eastern Canada ◽  
Ice Load ◽  
Flexural Failure ◽  
Conical Structure ◽  
Ice Loads ◽  
Failure Models ◽  
Bridge Spans

The Confederation Bridge spans across the Northumberland Strait in Eastern Canada connecting Prince Edward Island to mainland Canada through New Brunswick. Due to the presence of ice during each winter, the bridge piers are subjected to ice loads. A comprehensive permanent monitoring program has been implemented to observe and measure the ice–structure interaction events at two piers since the start of the bridge operations in 1998. This study uses the derived ice loads on one pier, and the associated event attributes for 100 selected events. Flexural failure models are used to determine theoretical loads of the selected interaction events. It is found that the weight of the total ice rubble pile and the physical and mechanical properties of the ice sheet are the dominant parameters affecting the ice load exerted on the conical structure. A semi-empirical correlation is developed to relate the ice load with those parameters for the Confederation Bridge.

Velocity Effects on Conical Structure Ice Loads

2002 ◽  
Author(s):  
Dmitri G. Matskevitch
Keyword(s):  
Model Tests ◽  
Ice Load ◽  
Empirical Correction ◽  
Conical Structure ◽  
Ice Loads ◽  
Ice Velocity ◽  
Velocity Effect ◽  
Ice Failure ◽  
Bending Failure ◽  
Conical Structures

Existing design codes and most methods for ice load calculation for conical structures do not take velocity effects into account. They were developed as an upper bound estimate for the load from slow moving ice which fails in bending against the cone. Velocity effects can be ignored when the structure is designed for an area with slow ice movement, for example, the nearshore Beaufort Sea. Sakhalin structures will be exposed to ice moving at velocities up to about 1.5 m/sec. Model tests show that quasi-static methods may underestimate the ice load on a steep cone when the interaction velocity is that high. The present paper summarizes results of published model tests with conical structures that show a velocity effect. An empirical correction factor to the Ralston method is developed to account for the increase in cone load with ice velocity. The paper also discusses velocity effects on ice failure length and possible transition from bending failure to an alternative failure mode when the ice velocity is high.

Station Keeping Trials in Ice: Ice Load Monitoring System

2018 ◽  
Author(s):  
Håvard Nyseth ◽  
Anders Hansson ◽  
Johan Johansson Iseskär
Keyword(s):  
Data Sets ◽  
Station Keeping ◽  
Ice Load ◽  
Hull Structure ◽  
Load Monitoring ◽  
Ice Loads ◽  
Recorded Data ◽  
Measurement Concept ◽  
Ice Impacts ◽  
Basic Philosophy

In connection with the Statoil SKT project, DNV GL have developed a method for estimating ice loads on the ship hull structure and mooring tension of the anchor handling tug supply (AHTS) vessel Magne Viking by full scale measurements. In March 2017, the vessel was equipped with an extensive measurement system as a preparation for the dedicated station-keeping trial in drifting ice in the Bay of Bothnia. Data of the ice impacts acting on the hull were collected over the days of testing together with several other parameters from the ship propulsion system. Whilst moored, the tension in the mooring chain was monitored via a load cell and logged simultaneously to the other parameters. This paper presents the processes involved in developing the measurement concept, including the actual installation and execution phases. The basic philosophy behind the system is described, including the methods used to design an effective measurement arrangement, and develop procedures for estimation of ice loads based on strain measurements. The actual installation and the process of obtaining the recorded data sets are also discussed.

A Three-Dimensional Model for Ice Rubble Pile-Ice Sheet-Conical Structure Interaction at the Piers of Confederation Bridge, Canada

2018 ◽  
Vol 140 (5) ◽  
Author(s):  
Chee K. Wong ◽  
Thomas G. Brown
Keyword(s):  
Three Dimensional ◽  
Ice Sheet ◽  
Offshore Structures ◽  
Flexural Behavior ◽  
Small Scale ◽  
Structure Interaction ◽  
Flexural Failure ◽  
Modes Of Failure ◽  
Conical Structure ◽  
Rubble Pile

Offshore structures constructed in waters where ice cover is prevalent for several months a year are subjected to ice loading. Some of these structures are conical or sloped-faced in shape, where flexural failure becomes the dominant mode of failure for the ice sheet. The flexural failure mode reduces the magnitude of ice-structure interaction loads in comparison to other modes of failure. Various researchers have devised flexural failure models for ice-conical structure interactions. Each model shares the same principle of the ice sheet being modeled as a beam on an elastic foundation, but each model has different limitations in precisely simulating the interaction. Some models do not incorporate the ice rubble pile, while other models make oversimplified assumptions for three-dimensional behavior. The proposed three-dimensional (3D) model aims to reduce some of these limitations with the following features: (1) modeling the geometry of the ice rubble pile around the conical pier using the results of small-scale tests, (2) modeling the loads exerted by the ice rubble pile on the conical structure and ice sheet with a rigorous method of slices, (3) adding driving forces in keeping the rubble pile intact and in upward motion during the interaction, (4) accounting for eccentric offsetting moments at the ice-structure contacts, and (5) modeling the flexural behavior of the ice sheet subject to ice rubble loads using finite element method. The proposed model is used to analyze the interaction events recorded at the conical piers of the Confederation Bridge over a period of 11 years.

Scale Effect in Ice Flexural Strength

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
Mohamed Aly ◽  
Rocky Taylor ◽  
Eleanor Bailey Dudley ◽  
Ian Turnbull
Keyword(s):  
Flexural Strength ◽  
Sea Ice ◽  
Probabilistic Models ◽  
Scale Effects ◽  
Offshore Structures ◽  
Bridge Piers ◽  
Freshwater Ice ◽  
Flexural Failure ◽  
Ice Loads ◽  
Ice Strength

Ice flexural strength is an important parameter in the assessment of ice loads on the hulls of ice-class ships, sloped offshore structures, and sloped bridge piers. While scale effects in compressive ice strength are well known, there has been debate as to the extent of scale effects in ice flexural strength. To investigate scale effects during flexural failure of both freshwater and saline ice, a comprehensive up-to-date database of beam flexural strength measurements has been compiled. The database includes 2073 freshwater ice beam tests with beam volumes between 0.00016 and 2.197 m3, and 2843 sea ice beam tests with volumes between 0.00048 and 59.87 m3. The data show a considerable decrease in flexural strength as the specimen size increases, when examined over a large range of scales. Empirical models of freshwater ice flexural strength as a function of beam volume, and of saline ice as function of beam and brine volumes have been developed using regression analysis. For freshwater ice, the scale-dependent flexural strength is given as: σf=839(V/V1)−0.13 For sea ice, the dependence of flexural strength has been modeled as: σ=1324(V/V1)−0.054e−4.969vb. Probabilistic models based on the empirical data were developed based on an analysis of the residuals, and can be used to enhance probabilistic analysis of ice loads where ice flexural strength is an input.

Scale Effect in Freshwater Ice Flexural Strength

2018 ◽  
Author(s):  
Mohamed Aly ◽  
Rocky Taylor ◽  
Eleanor Bailey Dudley ◽  
Ian Turnbull
Keyword(s):  
Flexural Strength ◽  
Large Range ◽  
Scale Effects ◽  
Offshore Structures ◽  
Bridge Piers ◽  
Considerable Decrease ◽  
Freshwater Ice ◽  
Flexural Failure ◽  
Ice Loads ◽  
Ice Strength

Ice flexural strength is an important parameter in the assessment of ice loads on the hulls of ice-class ships, sloped offshore structures or sloped bridge piers. While scale effects are well known for compressive ice strength, there has been debate as to whether or not scale effects in ice flexural strength exist. To investigate scale effects during flexural failure of freshwater ice, a comprehensive up-to-date database of beam flexural strength measurements has been compiled. The data show a considerable decrease in flexural strength as the specimen size increases, when examined over a large range of scales. An empirical model of freshwater ice flexural strength as a function of beam volume has been developed using regression analysis.

Interaction of Ice Floes With Columns of a Semi-Submersible Platform

1983 ◽  
Vol 105 (4) ◽  
pp. 460-463
Author(s):  
P. G. Noble ◽  
D. Singh
Keyword(s):  
Maximum Load ◽  
Test Results ◽  
Ice Load ◽  
Physical Model Tests ◽  
Ice Concentration ◽  
Drilling Unit ◽  
Ice Loads ◽  
Ice Field ◽  
Preliminary Research ◽  
Ice Floes

A preliminary research project has been carried out to determine the effect of small ice floes on a semi-submersible drilling unit. Physical model tests have been conducted with two main objectives: first, to determine the ability of the columns to prevent ice from passing between them (arching) and thus minimizing the chance of riser damage, and second, to determine the total ice load on the semi-submersible during interaction with ice field concentrations. Three models were used, representing one half of a four, six or eight-legged semi-submersible platform. The dimensions and spacing of the columns were such that the heave and pitch responses were kept constant. The tests were conducted at a model scale of 1:30 using synthetic ice. Test results showed the maximum load measured on a four-legged semi-submersible model, at 100 percent ice floe concentration, was on the order of half of that measured on six or eight-legged semi-submersible models. Also the ice loads on a four-legged semi-submersible model at lower ice floe concentration were substantially less than those for six or eight-legged semi-submersible models. The total ice load on semi-submersible models is found to be a function of ice floe concentration. Up to about 75 percent ice concentration, ice loads varied linearly. Beyond that, the loads increased exponentially for all semi-submersible models.

AEROMAGNETIC AND GEOLOGICAL INTERPRETATION OF A SECTION OF THE APPALACHIAN BELT IN CANADA

1967 ◽  
Vol 4 (6) ◽  
pp. 1015-1037 ◽  
Author(s):  
B. K. Bhattacharyya ◽  
B. Raychaudhuri
Keyword(s):  
Prince Edward Island ◽  
Bouguer Anomaly ◽  
Polarization Vector ◽  
Fault System ◽  
Aeromagnetic Data ◽  
Eastern Canada ◽  
Geological Interpretation ◽  
Vertical Displacements ◽  
Regional Tectonic ◽  
Anomaly Map

Studies were made of total field aeromagnetic data over an area covering a section of the Appalachian belt in eastern Canada. This area is bounded by latitudes 45 °N and 47°40′ N and longitudes 62°30′ W and 67 °W. The residual magnetic values were filtered analytically in order to accentuate the effects of regional tectonic trends in the area. The second vertical derivative values were evaluated for outlining the contacts of magnetized geological formations with a reasonable degree of accuracy. Results of the analysis of the Bouguer anomaly map for the area seemed to correspond well with the tectonic trends indicated by the aeromagnetic data. Sixty-five anomalies were chosen from the residual and filtered maps to determine the following parameters of the causative bodies: (1) intensity of polarization; (2) direction-cosines of the polarization vector; and (3) depths to the top and bottom of the bodies.The picture of the pre-Carboniferous basement, as inferred from aeromagnetic data, is that of a valley and ridge configuration characterized by a series of subparallel, elongated basement blocks with relative vertical displacements. The basement blocks are bounded by major fault systems, known or inferred, mostly of pre-Carboniferous age. These blocks are aligned mostly in the direction of major tectonic trend in the area. The details of subsurface Basement topography are discussed on the basis of the results of interpretation of aeromagnetic data. Most interesting of all is a belt of high magnetic intensity running roughly in a NW–SE direction over the Gulf of St. Lawrence and Prince Edward Island. It has been suggested that this belt is caused by a pre-Taconic topographic high, or alternatively, by a pre-Carboniferous basement high bounded by fault zones subparallel with the fault system under the Cabot Strait.

Reliability Against Drifting Ice—An Adjunct to Monte Carlo Simulation

1991 ◽  
Vol 113 (3) ◽  
pp. 253-259
Author(s):  
A. B. Dunwoody
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Normal Family ◽  
Probability Distributions ◽  
Load Model ◽  
Ice Load ◽  
Ice Loads ◽  
Drifting Ice ◽  
Log Normal ◽  
Monte Carlo Simulation Program

A method is presented for the calculation of the reliability of a structure against drifting ice subject to restrictions on the form of the ice load model and on the form of the probability distributions of the ice feature characteristics. The ice load model must have the form that the ice load is proportional to the product of the characteristics of the impacting ice feature raised to individual powers. Results from a Monte Carlo simulation program are presented to demonstrate that the ice loads for a number of useful ice interaction scenarios can be modeled by an equation of this form. The probability distributions of the ice feature characteristics must be from the log-normal family. A realistic example using publicly available ice data and ice load model is presented.

Iona barley

1993 ◽  
Vol 73 (4) ◽  
pp. 1083-1086
Author(s):  
T. M. Choo ◽  
J. D. E. Sterling ◽  
R. A. Martin ◽  
J. S. Bubar ◽  
R. Walton ◽  
...  
Keyword(s):  
Hordeum Vulgare ◽  
Powdery Mildew ◽  
Prince Edward Island ◽  
High Yield ◽  
Research Station ◽  
Intensive Management ◽  
Good Resistance ◽  
Hordeum Vulgare L ◽  
Eastern Canada ◽  
Breeder Seed

Iona is a two-row, spring feed barley (Hordeum vulgare L.) developed at the Agriculture Canada Research Station, Charlottetown, Prince Edward Island. It has high yield and good resistance to powdery mildew. Iona is well adapted to Eastern Canada and is responsive to intensive management. Breeder seed is maintained at the Agriculture Canada Experimental Farm, Indian Head, Saskatchewan. Key words: Hordeum vulgare L., two-row barley, feed barley, high yield

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