Ice action on fixed offshore structures: a state-of-the-art review

1987 ◽  
Vol 14 (3) ◽  
pp. 381-407 ◽  
Author(s):  
M. A. Nessim ◽  
M. S. Cheung ◽  
I. J. Jordaan
Keyword(s):  
Interaction Design ◽  
Size Effects ◽  
Offshore Structures ◽  
Probabilistic Methods ◽  
Background Information ◽  
Design Criteria ◽  
Load Calculation ◽  
Ice Conditions ◽  
Ice Loads ◽  
Probabilistic Load

The methods and approaches for calculating global ice loads on fixed offshore structures are critically reviewed. The review covers both the mechanical approaches used in load calculation and the probabilistic methods used to deal with the uncertainties involved. The paper gives a brief review of background information related to ice conditions, ice-load characterization, and ice mechanics. Load calculation methods for different types of ice behaviour are reviewed for vertical structures, as well as sloping-sided structures. Size effects are discussed, and the effects of rubble piles on ice loads are briefly reviewed. The emphasis of the review is on summarizing the different models and approaches reported in the literature, and making evaluations, comments, and suggestions for further research from the viewpoint of choosing design criteria. Key words: ice-structure interaction, design criteria, ice indentation, probabilistic load assessment, Arctic structures, size effects.

Probabilistic Modeling of Extreme Value Distributions of Ice Loads on “Molikpaq” Platform for Sakhalin-II Project

2013 ◽  
Author(s):  
Alexander T. Bekker ◽  
Olga A. Sabodash ◽  
Roman G. Kovalenko
Keyword(s):  
Numerical Modeling ◽  
Return Period ◽  
Statistical Data ◽  
Extreme Values ◽  
Ice Cover ◽  
Offshore Structures ◽  
Extreme Value Distributions ◽  
Probabilistic Estimation ◽  
Ice Conditions ◽  
Ice Loads

Characteristics of the drifting ice cover and the scenarios of the ice loads on offshore structures are the major parameters defining durability and reliability of the ice-resistant platforms on the Sakhalin offshore. The study is devoted to the problems of probabilistic and numerical modeling of the process of interaction between the ice cover and the ice-resistant concrete structures on the Sakhalin offshore zone. Geometry of the “Molikpaq” (PA-A) platform for Sakhalin-II Project is used as an example. The input statistical data were received on the basis of full-scale observations of the ice conditions in the Piltun-Astokhskoe deposit area during 1989–2002. The distribution of probability exceedance of ice loads for various ice scenarios on the “Molikpaq” (PA-A) platform was received. A probabilistic estimation of extreme values of ice loads was carried out, taking into account return period of ice conditions.

Methodology to Evaluate Sea Ice Loads for Seasonal Operations

2015 ◽  
Author(s):  
Jan Thijssen ◽  
Mark Fuglem
Keyword(s):  
Sea Ice ◽  
Offshore Structures ◽  
Ice Thickness ◽  
Safety Level ◽  
Site Specific ◽  
Design Load ◽  
Ice Load ◽  
Ice Conditions ◽  
Design Loads ◽  
Ice Loads

Offshore structures designed for operation in regions where sea ice is present will include a sea ice load component in their environmental loading assessment. Typically ice loads of interest are for 10−2, 10−3 or 10−4 annual probability of exceedance (APE) levels, with appropriate factoring to the required safety level. The ISO 19906 standard recommends methods to determine global sea ice loads on vertical structures, where crushing is the predominant failure mode. Fitted coefficients are proposed for both Arctic and Sub-Arctic (e.g. Baltic) conditions. With the extreme ice thickness expected at the site of interest, an annual global sea ice load can be derived deterministically. Although the simplicity of the proposed relation provides quick design load estimates, it lacks accuracy because the only dependencies are structure width, ice thickness and provided coefficients; no consideration is given to site-specific sea ice conditions and the corresponding exposure. Additionally, no term is provided for including ice management in the design load basis. This paper presents a probabilistic methodology to modify the deterministic ISO 19906 relations for determining global and local first-year sea ice loads on vertical structures. The presented methodology is based on the same ice pressure data as presented in ISO 19906, but accounts better for the influence of ice exposure, ice management and site-specific sea ice data. This is especially beneficial for ice load analyses of seasonal operations where exposure to sea ice is limited, and only thinner ice is encountered. Sea ice chart data can provide site-specific model inputs such as ice thickness estimates and partial concentrations, from which corresponding global load exceedance curves are generated. Example scenarios show dependencies of design loads on season length, structural geometry and sea ice conditions. Example results are also provided, showing dependency of design loads on the number of operation days after freeze-up, providing useful information for extending the drilling season of MODUs after freeze-up occurs.

Technical Solutions of the Active Ice Protection of Offshore Structures for the Russian Arctic

2016 ◽  
Author(s):  
Olga A. Sabodash ◽  
Valerii V. Tarasov
Keyword(s):  
Offshore Structures ◽  
Cad System ◽  
Offshore Production ◽  
Calculation Results ◽  
Ice Conditions ◽  
Ice Loads ◽  
Ice Field ◽  
Solid Works ◽  
Main Components ◽  
Technical Solutions

The device for active protection against ice loads using pneumatic soft shells (PSS) on offshore production platforms has been studied. For technical modeling of devices the Solid Works CAD system was applied. The calculation results of model of the main components of the device by contact with the ice field in the Sea of Okhotsk ice conditions have been obtained. Finally, recommendations on the future effective application of the structures ice protective equipment have been worked out.

Wave and current forces on fixed offshore structures

1988 ◽  
Vol 15 (6) ◽  
pp. 937-947 ◽  
Author(s):  
Michael Isaacson
Keyword(s):  
Key Words ◽  
Recent Literature ◽  
Offshore Structures ◽  
Design Criteria ◽  
Wave Forces ◽  
Ocean Engineering ◽  
Detailed Survey ◽  
Ice Loads ◽  
Hydrodynamic Data ◽  
Design Construction

The Canadian Standards Association standard S471 "General requirements, design criteria, environment, and loads, Part 1 of the CSA code for the design, construction and installation of fixed offshore structures" contains an appendix "Wave and current loads." To compliment this appendix, the present paper provides a more detailed survey of this topic with a review of the recent literature and recommendations of hydrodynamic data needed in offshore design. In addition, hydrodynamic considerations in the calculation of earthquake and ice loads are mentioned. Key words: currents, current forces, hydrodynamics, ocean engineering, offshore structures, waves, wave forces.

Ice Model Tests for Semi-Submersible Platforms in Pack Ice Conditions

2019 ◽  
Author(s):  
Liu Luping ◽  
Li Xin ◽  
Wu Xiao ◽  
Wu Bo
Keyword(s):  
Offshore Structures ◽  
The Arctic ◽  
Floating Platform ◽  
Oil Exploitation ◽  
Pack Ice ◽  
Ice Drift ◽  
Load Cells ◽  
Ice Conditions ◽  
Ice Loads ◽  
Similar Density

Abstract As development of the Arctic grows in intensity, semi-submersible platforms are one of promising type of offshore structures used for arctic oil exploitation. Generally a good ice management is equipped by a moored floating platform to reduce ice loads to manageable levels, thus the most common scenario for a polar operating semi-submersible platform is pack ice conditions. The resistance test of a 4-columns structure is performed in a normal towing tank in China using synthetic non-refrigerated material with similar density to model sea ice. Three component load cells on top of each column and a batch of single component load cells embedded in the surface of the columns near the waterline are used to measure indirect and direct ice loads on the structures. The effects of a series of parameters such as column shapes, orientations, column spacing ratios, ice floe shapes, ice drift speeds and ice concentrations are analyzed.

Thirteenth Canadian Geotechnical Colloquium: Ice design criteria for wide arctic structures

1990 ◽  
Vol 27 (6) ◽  
pp. 701-725 ◽  
Author(s):  
Denis Blanchet
Keyword(s):  
Key Words ◽  
Shear Zone ◽  
Design Criteria ◽  
Correction Factors ◽  
Return Periods ◽  
Ice Load ◽  
Risk Probability ◽  
Arctic Exploration ◽  
Ice Conditions ◽  
Ice Loads

The derivation of design global ice loads for wide vertical caisson-type arctic exploration structures is presented. Correction factors are applied to global ice-load data measured during ice–structure interactions to create a set of design criteria for two typical exploration structures: circular (100 m diameter) and rectangular (160 × 50 m). Return periods for the proposed deterministic design ice loads for these two structures are then determined for typical ice conditions encountered in the Harrison Bay shear zone area in 20–30 m of water. Key words: exploration structures, global design ice loads, risk, probability of exceedence, return periods.

Analysis of Ice Loads on Offshore Structures for Okhotsk Sea Oil and Gas Fields

2011 ◽  
Author(s):  
Alexander T. Bekker ◽  
Olga A. Sabodash ◽  
Aleksey Yu. Kochev
Keyword(s):  
Comparative Analysis ◽  
Probabilistic Model ◽  
Sea Of Okhotsk ◽  
Oil And Gas ◽  
Offshore Structures ◽  
Okhotsk Sea ◽  
Oil And Gas Fields ◽  
Ice Conditions ◽  
Ice Loads ◽  
Gas Fields

In the study, the results of a statistical modeling of ice loads from drifting ice features on the ice-resistant platforms in Piltun-Astohsky and Lunsky oil&gas fields of “Sakhalin-I” and “Sakhalin-II” Projects are investigated. The authors made a comparative analysis of ice loads on various types of gravity-based concrete structures in ice conditions of the Sea of Okhotsk according to the standards, procedures and guidelines from different Codes of design. And also the probabilistic model of ice loads, developed by the authors in the previous studies, was considered for comparative analysis.

Lateral Force Resisting Systems Made of Cold-Formed Steel Material: Proposal of Seismic Design Criteria for 2nd Generation of Eurocode 8

2021 ◽  
Vol 885 ◽  
pp. 127-132
Author(s):  
Sarmad Shakeel ◽  
Alessia Campiche
Keyword(s):  
Seismic Design ◽  
Shear Walls ◽  
Lateral Force ◽  
Background Information ◽  
Design Criteria ◽  
Eurocode 8 ◽  
Building Structures ◽  
Design Standards ◽  
Design Strength ◽  
Cold Formed Steel

The current edition of Eurocode 8 does not cover the design of the Cold-Formed steel (CFS) building structures under the seismic design condition. As part of the revision process of Euro-code 8 to reflect the outcomes of extensive research carried out in the past decade, University of Naples “Federico II” is involved in the validation of existing seismic design criteria and development of new rules for the design of CFS systems. In particular, different types of Lateral Force Resisting System (LFRS) are analyzed that can be listed in the second generation of Eurocode 8. The investigated LFRS’s include CFS strap braced walls and CFS shear walls with steel sheets, wood, or gypsum sheathing. This paper provides the background information on the research works and the reference design standards, already being used in some parts of the world, which formed the basis of design criteria for these LFRS systems. The design criteria for the LFRS-s common to CFS buildings would include rules necessary for ensuring the dissipative behavior, appropriate values of the behavior factor, guidelines to predict the design strength, geometrical and mechanical limitations.

Parameter Sensitivity in Numerical Modelling of Ice-Structure Interaction With Cohesive Element Method

2016 ◽  
Author(s):  
Dianshi Feng ◽  
Sze Dai Pang ◽  
Jin Zhang
Keyword(s):  
Element Model ◽  
Offshore Structures ◽  
Parameter Sensitivity ◽  
The Arctic ◽  
Cohesive Element ◽  
Structure Interaction ◽  
Marine Structure ◽  
Ice Loads ◽  
The Stability ◽  
Element Method

The increasing marine activities in the Arctic has resulted in a growing demand for reliable structural designs in this region. Ice loads are a major concern to the designer of a marine structure in the arctic, and are often the principal factor that governs the structural design [Palmer and Croasdale, 2013]. With the rapid advancement in computational power, numerical method is becoming a useful tool for design of offshore structures subjected to ice actions. Cohesive element method (CEM), a method which has been widely utilized to simulate fracture in various materials ranging from metals to ceramics and composites as well as bi-material systems, has been recently applied to predict ice-structure interactions. Although it shows promising future for further applications, there are also some challenging issues like high mesh dependency, large variation in cohesive properties etc., yet to be resolved. In this study, a 3D finite element model with the use of CEM was developed in LS-DYNA for simulating ice-structure interaction. The stability of the model was investigated and a parameter sensitivity analysis was carried out for a better understanding of how each material parameter affects the simulation results.

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