Dynamic ice structure interaction

Theory and applications: Dissertation

Esa Eranti

Research output: ThesisDissertationMonograph

Abstract

A theory of dynamic ice-structure interaction is described with transverse and torsional vibrations included. The theory is applicable to cases of pure crushing of ice against vertical structures as well as combined crushing and shearing of ice against inclined structures. The zonal ice failure approach is adapted, the structure being locally in contact with solid and broken ice alternately. Simple rules are given for the development of the zonal ice force in the interaction process. The structural response, the zonal ice force components and the global ice force are found in an iterative step-by-step procedure based on the development the theoretical distance between the zonal contact point and the ice edge. A number of medium scale ice-structure interaction tests were performed in the VTT ice tank using freshwater columnar grained ice. The mass and the stiffness of the vibrating system, pushing velocity, and the aspect ratio, shape and inclination of the contact face were varied. Highest effective ice pressures were measured for flexible systems with vertical contact face. Interaction coefficients that quantity the zonal interaction process are obtained based on the test results. Simulations of the interaction tests using these coefficients give response, acceleration and ice force records that are in good agreement with measured ones over the whole range of cases. Moreover, simulations of ice interaction with full scale structures using these same coefficients provide results that are in reasonable agreement with available field experience. The study concludes that the common practice of using aspect ratio curves or pressure-area curves to predict effective ice pressures caused by columnar grained level ice is generally invalid and may in some cases be even dangerous. Each situation is a special case of dynamic ice-structure interaction and the effective ice pressure and the structural response records depend strongly on the geometric and dynamic properties of the structure. The proposed approach provides an upper bound solution for global ice force and structural response, in the sense that it assumes pure crushing or combined crushing and shearing failure of ice, and ignores reductions that may result from other failure modes.
Original languageEnglish
QualificationDoctor Degree
Awarding Institution
  • Helsinki University of Technology
Supervisors/Advisors
  • Mikkola, Martti, Supervisor, External person
Award date3 Apr 1992
Place of PublicationEspoo
Publisher
Print ISBNs951-38-4068-9
Publication statusPublished - 1992
MoE publication typeG4 Doctoral dissertation (monograph)

Fingerprint

Ice
Crushing
Shearing
Aspect ratio
Point contacts

Keywords

  • ice
  • ice loads
  • dynamic loads
  • loads (forces)
  • dynamic structural analysis
  • structures
  • interactions
  • utilization
  • dynamic properties
  • models
  • theories
  • simulation
  • vibration
  • tests
  • comparison
  • failure

Cite this

Eranti, E. (1992). Dynamic ice structure interaction: Theory and applications: Dissertation. Espoo: VTT Technical Research Centre of Finland.
Eranti, Esa. / Dynamic ice structure interaction : Theory and applications: Dissertation. Espoo : VTT Technical Research Centre of Finland, 1992. 87 p.
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title = "Dynamic ice structure interaction: Theory and applications: Dissertation",
abstract = "A theory of dynamic ice-structure interaction is described with transverse and torsional vibrations included. The theory is applicable to cases of pure crushing of ice against vertical structures as well as combined crushing and shearing of ice against inclined structures. The zonal ice failure approach is adapted, the structure being locally in contact with solid and broken ice alternately. Simple rules are given for the development of the zonal ice force in the interaction process. The structural response, the zonal ice force components and the global ice force are found in an iterative step-by-step procedure based on the development the theoretical distance between the zonal contact point and the ice edge. A number of medium scale ice-structure interaction tests were performed in the VTT ice tank using freshwater columnar grained ice. The mass and the stiffness of the vibrating system, pushing velocity, and the aspect ratio, shape and inclination of the contact face were varied. Highest effective ice pressures were measured for flexible systems with vertical contact face. Interaction coefficients that quantity the zonal interaction process are obtained based on the test results. Simulations of the interaction tests using these coefficients give response, acceleration and ice force records that are in good agreement with measured ones over the whole range of cases. Moreover, simulations of ice interaction with full scale structures using these same coefficients provide results that are in reasonable agreement with available field experience. The study concludes that the common practice of using aspect ratio curves or pressure-area curves to predict effective ice pressures caused by columnar grained level ice is generally invalid and may in some cases be even dangerous. Each situation is a special case of dynamic ice-structure interaction and the effective ice pressure and the structural response records depend strongly on the geometric and dynamic properties of the structure. The proposed approach provides an upper bound solution for global ice force and structural response, in the sense that it assumes pure crushing or combined crushing and shearing failure of ice, and ignores reductions that may result from other failure modes.",
keywords = "ice, ice loads, dynamic loads, loads (forces), dynamic structural analysis, structures, interactions, utilization, dynamic properties, models, theories, simulation, vibration, tests, comparison, failure",
author = "Esa Eranti",
note = "Project code: RAT8026",
year = "1992",
language = "English",
isbn = "951-38-4068-9",
series = "VTT Publications",
publisher = "VTT Technical Research Centre of Finland",
number = "90",
address = "Finland",
school = "Helsinki University of Technology",

}

Eranti, E 1992, 'Dynamic ice structure interaction: Theory and applications: Dissertation', Doctor Degree, Helsinki University of Technology, Espoo.

Dynamic ice structure interaction : Theory and applications: Dissertation. / Eranti, Esa.

Espoo : VTT Technical Research Centre of Finland, 1992. 87 p.

Research output: ThesisDissertationMonograph

TY - THES

T1 - Dynamic ice structure interaction

T2 - Theory and applications: Dissertation

AU - Eranti, Esa

N1 - Project code: RAT8026

PY - 1992

Y1 - 1992

N2 - A theory of dynamic ice-structure interaction is described with transverse and torsional vibrations included. The theory is applicable to cases of pure crushing of ice against vertical structures as well as combined crushing and shearing of ice against inclined structures. The zonal ice failure approach is adapted, the structure being locally in contact with solid and broken ice alternately. Simple rules are given for the development of the zonal ice force in the interaction process. The structural response, the zonal ice force components and the global ice force are found in an iterative step-by-step procedure based on the development the theoretical distance between the zonal contact point and the ice edge. A number of medium scale ice-structure interaction tests were performed in the VTT ice tank using freshwater columnar grained ice. The mass and the stiffness of the vibrating system, pushing velocity, and the aspect ratio, shape and inclination of the contact face were varied. Highest effective ice pressures were measured for flexible systems with vertical contact face. Interaction coefficients that quantity the zonal interaction process are obtained based on the test results. Simulations of the interaction tests using these coefficients give response, acceleration and ice force records that are in good agreement with measured ones over the whole range of cases. Moreover, simulations of ice interaction with full scale structures using these same coefficients provide results that are in reasonable agreement with available field experience. The study concludes that the common practice of using aspect ratio curves or pressure-area curves to predict effective ice pressures caused by columnar grained level ice is generally invalid and may in some cases be even dangerous. Each situation is a special case of dynamic ice-structure interaction and the effective ice pressure and the structural response records depend strongly on the geometric and dynamic properties of the structure. The proposed approach provides an upper bound solution for global ice force and structural response, in the sense that it assumes pure crushing or combined crushing and shearing failure of ice, and ignores reductions that may result from other failure modes.

AB - A theory of dynamic ice-structure interaction is described with transverse and torsional vibrations included. The theory is applicable to cases of pure crushing of ice against vertical structures as well as combined crushing and shearing of ice against inclined structures. The zonal ice failure approach is adapted, the structure being locally in contact with solid and broken ice alternately. Simple rules are given for the development of the zonal ice force in the interaction process. The structural response, the zonal ice force components and the global ice force are found in an iterative step-by-step procedure based on the development the theoretical distance between the zonal contact point and the ice edge. A number of medium scale ice-structure interaction tests were performed in the VTT ice tank using freshwater columnar grained ice. The mass and the stiffness of the vibrating system, pushing velocity, and the aspect ratio, shape and inclination of the contact face were varied. Highest effective ice pressures were measured for flexible systems with vertical contact face. Interaction coefficients that quantity the zonal interaction process are obtained based on the test results. Simulations of the interaction tests using these coefficients give response, acceleration and ice force records that are in good agreement with measured ones over the whole range of cases. Moreover, simulations of ice interaction with full scale structures using these same coefficients provide results that are in reasonable agreement with available field experience. The study concludes that the common practice of using aspect ratio curves or pressure-area curves to predict effective ice pressures caused by columnar grained level ice is generally invalid and may in some cases be even dangerous. Each situation is a special case of dynamic ice-structure interaction and the effective ice pressure and the structural response records depend strongly on the geometric and dynamic properties of the structure. The proposed approach provides an upper bound solution for global ice force and structural response, in the sense that it assumes pure crushing or combined crushing and shearing failure of ice, and ignores reductions that may result from other failure modes.

KW - ice

KW - ice loads

KW - dynamic loads

KW - loads (forces)

KW - dynamic structural analysis

KW - structures

KW - interactions

KW - utilization

KW - dynamic properties

KW - models

KW - theories

KW - simulation

KW - vibration

KW - tests

KW - comparison

KW - failure

M3 - Dissertation

SN - 951-38-4068-9

T3 - VTT Publications

PB - VTT Technical Research Centre of Finland

CY - Espoo

ER -

Eranti E. Dynamic ice structure interaction: Theory and applications: Dissertation. Espoo: VTT Technical Research Centre of Finland, 1992. 87 p.