Non-linear Wave Load Model to Predict the High Frequency Deep Wave Impact Forces on Offshore Structures

A simplified wave impact load model to predict the additional impact (Ringing) load due to a high frequency steep wave at near breaking condition is presented in this paper. Model tests and field experience of offshore structures have shown that loads on large surface piercing structures, such as co...

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Main Author: Jayakumar, Muthuramalingam
Other Authors: Chan Koon Choi
Format: Conference Paper
Published: Techno-Press 2010
Subjects:
Online Access:http://hdl.handle.net/20.500.11937/47860
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author Jayakumar, Muthuramalingam
author2 Chan Koon Choi
author_facet Chan Koon Choi
Jayakumar, Muthuramalingam
author_sort Jayakumar, Muthuramalingam
building Curtin Institutional Repository
collection Online Access
description A simplified wave impact load model to predict the additional impact (Ringing) load due to a high frequency steep wave at near breaking condition is presented in this paper. Model tests and field experience of offshore structures have shown that loads on large surface piercing structures, such as columns of concrete gravity structures, in steep wave condition are considerably larger than those assumed in conventional design calculations. In extreme, near breaking wave conditions, offshore platforms exhibit significant resonant response called ringing. The ringing effect occurs like irregularly spaced bursts of response at the natural frequency of the structure. The bursts must be superimposed on the response predicted by traditional linear theory. The wave load model is developed based on Morison?s equation supplemented with a wave slap term. Water particle kinematics used in the present model is predicted using the Stokes fifth order wave theory. The simplified wave impact load model is validated with experimental results by Zou and Kim (1995).The validation of load model shows good agreement with the experimental and analytical values obtained by Zou and Kim (1995). A computer program has been formulated based on the model to obtain the wave loads at all discretised nodes, along the length of column from instantaneous free water surface to the bottom of the column at mud level for the given depth of water, wave height, period of time and size of the column and to calculate the non-dimensional load coefficient for all nodes. The predicted wave loads vary hyperbolically along the length of the column. The simplified wave impact load model enables practical applicability without involving tedious computational efforts and saves computational time and space.
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format Conference Paper
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institution Curtin University Malaysia
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last_indexed 2025-11-14T09:36:14Z
publishDate 2010
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spelling curtin-20.500.11937-478602019-03-08T10:36:19Z Non-linear Wave Load Model to Predict the High Frequency Deep Wave Impact Forces on Offshore Structures Jayakumar, Muthuramalingam Chan Koon Choi wave slam forces offshore structures ringing load wave load model A simplified wave impact load model to predict the additional impact (Ringing) load due to a high frequency steep wave at near breaking condition is presented in this paper. Model tests and field experience of offshore structures have shown that loads on large surface piercing structures, such as columns of concrete gravity structures, in steep wave condition are considerably larger than those assumed in conventional design calculations. In extreme, near breaking wave conditions, offshore platforms exhibit significant resonant response called ringing. The ringing effect occurs like irregularly spaced bursts of response at the natural frequency of the structure. The bursts must be superimposed on the response predicted by traditional linear theory. The wave load model is developed based on Morison?s equation supplemented with a wave slap term. Water particle kinematics used in the present model is predicted using the Stokes fifth order wave theory. The simplified wave impact load model is validated with experimental results by Zou and Kim (1995).The validation of load model shows good agreement with the experimental and analytical values obtained by Zou and Kim (1995). A computer program has been formulated based on the model to obtain the wave loads at all discretised nodes, along the length of column from instantaneous free water surface to the bottom of the column at mud level for the given depth of water, wave height, period of time and size of the column and to calculate the non-dimensional load coefficient for all nodes. The predicted wave loads vary hyperbolically along the length of the column. The simplified wave impact load model enables practical applicability without involving tedious computational efforts and saves computational time and space. 2010 Conference Paper http://hdl.handle.net/20.500.11937/47860 Techno-Press restricted
spellingShingle wave slam forces
offshore structures
ringing load
wave load model
Jayakumar, Muthuramalingam
Non-linear Wave Load Model to Predict the High Frequency Deep Wave Impact Forces on Offshore Structures
title Non-linear Wave Load Model to Predict the High Frequency Deep Wave Impact Forces on Offshore Structures
title_full Non-linear Wave Load Model to Predict the High Frequency Deep Wave Impact Forces on Offshore Structures
title_fullStr Non-linear Wave Load Model to Predict the High Frequency Deep Wave Impact Forces on Offshore Structures
title_full_unstemmed Non-linear Wave Load Model to Predict the High Frequency Deep Wave Impact Forces on Offshore Structures
title_short Non-linear Wave Load Model to Predict the High Frequency Deep Wave Impact Forces on Offshore Structures
title_sort non-linear wave load model to predict the high frequency deep wave impact forces on offshore structures
topic wave slam forces
offshore structures
ringing load
wave load model
url http://hdl.handle.net/20.500.11937/47860