The Experts below are selected from a list of 7005 Experts worldwide ranked by ideXlab platform
Kok Hon Chew - One of the best experts on this subject based on the ideXlab platform.
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optimization of offshore wind turbine support structures using an analytical gradient based method
Energy Procedia, 2015Co-Authors: Kok Hon Chew, Kang Tai, Michael MuskulusAbstract:Abstract Design optimization of offshore wind turbine support structures is an expensive task; due to the highly-constrained, non-convex and non-linear nature of the Design problem. This paper presents an analytical gradient-based method to solve this problem in an efficient and effective way. The Design sensitivities of the objective and constraint functions are evaluated analytically while the optimization of the structure is performed, subject to sizing, eigenfrequency, extreme load and fatigue load constraints. A case study was carried out for the OC4 Jacket substructure to evaluate the method. Results show that an optimal Jacket Design with 52 percent structural mass reduction was attained in 27 iterations, while satisfying all Design constraints under the simplified load cases used. Besides, it is shown that the analytical sensitivity analysis was more accurate and efficient than the often used finite difference approximations. It could avoid numerical artifacts that typically occur in the analysis of extreme load constraint sensitivities.
Donato Innamorato - One of the best experts on this subject based on the ideXlab platform.
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seismic retrofit of rc columns with continuous carbon fiber Jackets
Journal of Composites for Construction, 1997Co-Authors: Frieder Seible, M Nigel J Priestley, Gilbert A Hegemier, Donato InnamoratoAbstract:The development, the validation, and the implementation of a new seismic retrofit system for reinforced concrete columns are described. The column Jacketing system consists of continuous carbon fiber prepreg tows wound in an automated fashion onto existing circular or rectangular concrete columns, with variable Jacket thickness along the column height based on experimentally validated Design models. Jacket Design criteria for various seismic column failure modes are described and detailed examples show their application to retrofits of columns with circular and rectangular column geometry, different reinforcement ratios, and detailing. The carbon Jacket Designs are validated through large-scale bridge column model tests and are found to be just as effective as steel shell Jacketing in providing desired inelastic Design deformation capacity levels. Furthermore, it is shown that the retrofit criteria and guidelines are also applicable to other advanced composite Jacketing systems with appropriate considerat...
Raimund Rolfes - One of the best experts on this subject based on the ideXlab platform.
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a comprehensive fatigue load set reduction study for offshore wind turbines with Jacket substructures
Renewable Energy, 2018Co-Authors: Jan Hafele, Clemens Hubler, Cristian Guillermo Gebhardt, Raimund RolfesAbstract:Designing Jacket substructures for offshore wind turbines demands numerous time domain simulations to face different combinations of wind, wave, and current states. Regarding sophisticated Design methods incorporating structural optimization algorithms, a load set reduction is highly desirable. To obtain knowledge about the required size of the Design load set, a study on fatigue limit state load sets is conducted, which addresses mainly two aspects. The first one is a statistical evaluation of random subsets derived from probabilistic load sets with realistic environmental data obtained from the research platform FINO3. A full set comprising 2048 load simulations is gradually reduced to subsets and the results are compared to each other. The second aspect is a systematic load set reduction with the assumption of unidirectional wind, waves, and current. Firstly, critical directions are determined. Then, unidirectional load sets are systematically reduced. The corresponding damages are compared to those obtained from probabilistic load sets for eight test structures. It is shown that the omission of wind-, wave-, and current-misalignment does not necessarily imply an excessive simplification, if considered wisely. The outcome of this study can be used to decrease the numerical effort of the Jacket Design process and the levelized costs of energy.
Michael Muskulus - One of the best experts on this subject based on the ideXlab platform.
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optimization of offshore wind turbine support structures using an analytical gradient based method
Energy Procedia, 2015Co-Authors: Kok Hon Chew, Kang Tai, Michael MuskulusAbstract:Abstract Design optimization of offshore wind turbine support structures is an expensive task; due to the highly-constrained, non-convex and non-linear nature of the Design problem. This paper presents an analytical gradient-based method to solve this problem in an efficient and effective way. The Design sensitivities of the objective and constraint functions are evaluated analytically while the optimization of the structure is performed, subject to sizing, eigenfrequency, extreme load and fatigue load constraints. A case study was carried out for the OC4 Jacket substructure to evaluate the method. Results show that an optimal Jacket Design with 52 percent structural mass reduction was attained in 27 iterations, while satisfying all Design constraints under the simplified load cases used. Besides, it is shown that the analytical sensitivity analysis was more accurate and efficient than the often used finite difference approximations. It could avoid numerical artifacts that typically occur in the analysis of extreme load constraint sensitivities.
Frieder Seible - One of the best experts on this subject based on the ideXlab platform.
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seismic retrofit of rc columns with continuous carbon fiber Jackets
Journal of Composites for Construction, 1997Co-Authors: Frieder Seible, M Nigel J Priestley, Gilbert A Hegemier, Donato InnamoratoAbstract:The development, the validation, and the implementation of a new seismic retrofit system for reinforced concrete columns are described. The column Jacketing system consists of continuous carbon fiber prepreg tows wound in an automated fashion onto existing circular or rectangular concrete columns, with variable Jacket thickness along the column height based on experimentally validated Design models. Jacket Design criteria for various seismic column failure modes are described and detailed examples show their application to retrofits of columns with circular and rectangular column geometry, different reinforcement ratios, and detailing. The carbon Jacket Designs are validated through large-scale bridge column model tests and are found to be just as effective as steel shell Jacketing in providing desired inelastic Design deformation capacity levels. Furthermore, it is shown that the retrofit criteria and guidelines are also applicable to other advanced composite Jacketing systems with appropriate considerat...