An Experimental And Numerical Study Of Wind Turbine Seismic Behavior
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An Experimental And Numerical Study Of Wind Turbine Seismic Behavior
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Author : Ian Prowell
language : en
Publisher:
Release Date : 2011
An Experimental And Numerical Study Of Wind Turbine Seismic Behavior written by Ian Prowell and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with Earthquake resistant design categories.
This dissertation presents an experimental and numerical investigation into the seismic response of modern wind turbines. Currently, no consensus exists in the industry and there is significant interest in improving prediction of the behavior of wind turbines simultaneously subjected to wind, earthquake, and operational excitation. To this end, an experimental program was planned in order to evaluate seismic loading of wind turbines. In 2004, a preliminary shake table test of a 65-kW utility scale wind turbine was conducted that provided an experimental basis to begin the work discussed herein. A monitoring campaign was performed at Oak Creek Energy Systems in Mojave, California to assess variability of in-situ dynamic characteristics of two modern wind turbines (900-kW and 1.5-MW rated power) under different operational states and wind conditions. A second shake table experiment with a more extensive test program and improved instrumentation was executed, in which orientation of shaking and operational state were found to significantly influence response. Using the finite element program OpenSees, beam-column models of the tested specimens were constructed and calibrated. Collected data provided a basis to show that such a model could reproduce salient characteristics including natural frequencies, mode shapes, and dynamic response time histories for a parked turbine. In-situ results were used to guide construction of full turbine-foundation-soil models that provided insight into soil-structure interaction phenomena. An existing tool to simulate turbine dynamics, the FAST code, was extended to include seismic loading to allow simulation of operational turbines subjected to base shaking and validated based on shake table results. Using a calibrated model of the tested 900-kW turbine it is shown that neglecting aerodynamics results in significant over estimation of the tower bending demand. An investigation of turbines ranging from 65-kW to 5-MW concluded that consideration of aerodynamics and operational state becomes increasingly important with size. The updated FAST code was demonstrated to accurately reproduce observed dynamics of operating turbines, providing a validated tool for seismic design of turbines. These contributions clarify that operational state and orientation of shaking are important considerations and enable the development of a new generation of turbines that appropriately consider seismic loads.
Experimental And Numerical Seismic Response Of Offshore Wind Turbines Supported On Bucket Foundations
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Author : Muhammad Zayed
language : en
Publisher:
Release Date : 2022
Experimental And Numerical Seismic Response Of Offshore Wind Turbines Supported On Bucket Foundations written by Muhammad Zayed and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2022 with categories.
Bucket foundations have proven to be an efficient cost-effective option for a wide range of offshore applications. Motivated by the strong growth in offshore wind energy, this dissertation aims to investigate the seismic response of bucket foundations. A scaled soil-structure model of a 3.45 Megawatt (MW) utility-scale Offshore Wind Turbine (OWT) was tested on medium-size 1-g shake table. A preliminary testing phase resulted in developing new approaches for: i) tracking shear wave velocity variation within the ground during seismic excitation, and ii) generating accumulated ground deformation via asymmetric base shaking. Thereafter, the OWT model was subjected to a series of harmonic and earthquake-like excitations. From the collected data, key features of the overall system response were gleaned. Utilizing the experimental data, a nonlinear finite element (FE) model was calibrated to simulate the observed seismic response. The developed FE model was then extended to investigate the seismic behavior of a representative utility-scale OWT in sands under earthquake motions, combined with operational wind load effects. A parametric study is conducted to investigate influence of: i) soil stiffness and strength, ii) ground motion characteristics, iii) soil permeability, iv) bucket size, and v) damping on the OWT seismic response. The results suggest that: i) the near field pore water pressure build-up and bucket rotation are correlated, ii) ground motion characteristics have direct impact on the permanent bucket rotation, iii) lower soil permeability results in larger rotation due to the higher near field pore water pressure build-up, iv) permanent bucket rotation tends to reach a maximum and a minimum at the lower and upper bounds of soil permeability, respectively, reflecting the fully drained and undrained conditions, v) the difference in permanent bucket rotation between undrained and drained conditions tends to decrease with increasing soil stiffness, vi) Within the range of investigated scenarios, an essentially linear correlation was noted between the OWT fundamental frequency and the permanent bucket rotation, and vii) viscous damping at higher frequencies might have a significant effect on the bucket moment rotation response. As such, the gained insights provide guidance for seismic design of bucket foundation offshore wind turbines.
Experimental And Numerical Analysis Of Seismic Waves Produced By Wind Farms
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Author : Fabian Limberger
language : en
Publisher:
Release Date : 2023
Experimental And Numerical Analysis Of Seismic Waves Produced By Wind Farms written by Fabian Limberger and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2023 with categories.
Dynamic Response Analysis Of A 900 Kw Wind Turbine Subject To Ground Excitation
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Author : Adrian Felix Caudillo
language : en
Publisher:
Release Date : 2012
Dynamic Response Analysis Of A 900 Kw Wind Turbine Subject To Ground Excitation written by Adrian Felix Caudillo and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with categories.
This thesis exhibits the results of a study focused on the seismic behavior of a 900 kW wind turbine. As of the time of this writing, special engineering provisions for such loading events are not adequately defined. In order to accomplish the research objective, the author relies on available experimental data taken in 2009 from accelerometers attached to a wind turbine base and tower along with an eccentric mass shaker placed on the turbine foundation. On this basis, the dynamic properties of the wind turbine, including tower bending modes and natural frequencies were extracted. An attempt was made to quantify the damping ratios found in these bending modes by applying input shaking simulating the experimental excitation using the finite element program OpenSees. In this undertaking, possible sources of error are discussed. The author then describes a numerical study performed on a calibrated wind turbine like structure involving the application of a large range of actual recorded input motions. Adjustments are made to the original fixed-base model, placing the structure on a linearly elastic soil domain by using BridgePBEE, a graphical interface tool that eases simulation and functions as a pre and post processor. Using this code, the numerical study is further extended by varying the supporting ground stiffness. The study then compares the tower maximal shear and moment values for the studied rigid and flexible ground scenarios and explores trends in the lateral force lever-arm of the system.
Proceedings Of The 2022 International Conference On Green Building Civil Engineering And Smart City
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Author : Wei Guo
language : en
Publisher: Springer Nature
Release Date : 2022-09-07
Proceedings Of The 2022 International Conference On Green Building Civil Engineering And Smart City written by Wei Guo and has been published by Springer Nature this book supported file pdf, txt, epub, kindle and other format this book has been release on 2022-09-07 with Technology & Engineering categories.
This book of the conference proceedings focuses on innovative design, technology and methods in the fields of building, civil engineering and smart city. It contains a large number of detailed design, construction and performance analysis charts, benefited to students, teachers, research scholars and other professionals in related fields. As well, readers will encounter new ideas for realizing more safe, intelligent and economical buildings.
Experimental And Numerical Modeling Of The Response Of Foundations To Cyclic Loading For Offshore Structures
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Author : Bao Li Zheng
language : en
Publisher:
Release Date : 2018
Experimental And Numerical Modeling Of The Response Of Foundations To Cyclic Loading For Offshore Structures written by Bao Li Zheng and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018 with categories.
Design of offshore foundations can be difficult due to challenging soils that can vary from high plasticity, soft clay to very dense sand, and complex loading conditions from the respective environments (e.g., wind, waves, seismicity), in the form of combinations of monotonic and cyclic load patterns. Understanding the interaction of the soil-foundation-structure system under design loads is critical for reliable operations of offshore structures. This dissertation provides the evaluation of performance and investigation of mechanisms against cyclic loading for: (1) subsea wellhead-pipeline-manifold systems on soft clay; and (2) multi-pile-supported offshore wind turbine structures in dense sand. Commonly, the product from deep gas wells is collected at a central manifold founded on the seabed via jumpers (i.e., pipelines). The connections to the jumpers are relatively stiff, with limited tolerance against shear failure induced from relative displacement. A centrifuge test was conducted on the 9-m centrifuge at the UC Davis Center for Geotechnical Modeling to study the seismic performance of a caisson-supported manifold structure and a deeply-installed wellhead founded on soft clay when subjected to extreme and abnormal level earthquakes. Dynamic response of jumpers connecting the manifold structure and the wellhead was interpreted as the difference between the dynamic displacement time histories between the manifold structure, the wellhead, and the free-field clay surface. Comparison demonstrated that the governing jumper connections lie between the manifold and the wellhead and between the wellhead and the free-field surface, and the wellhead is the more critical component under the specific ground motion. Offshore wind turbine structures (OWTS) are subject to wind and wave loads with varying magnitudes of static and cyclic loads over their design lives. During normal operation, these structures are further loaded by rotor and blade-passing imbalance forces. Cyclic loading can cause significant degradation in the capacity and generate excessive movement, as well as reduction of the soil-pile stiffness and the natural frequency toward resonance with rotor frequencies. A centrifuge program was designed and performed on the 1-m Schaevitz centrifuge at UC Davis to evaluate the performance of tension piles against cyclic loads for multi-pile-supported offshore wind turbines. The potential for obtaining meaningful results using a small centrifuge for this application was demonstrated, and an initial data set from centrifuge testing of piles subjected to one-way and two-way cyclic axial loading was developed. The data set was presented and evaluated within the interaction diagram framework that is commonly used to predict the cyclic stability of piles. Results from the centrifuge tests were generally consistent with predictions from interaction diagrams (e.g., under one-way loading, increase in cyclic load amplitude lowers pile stability). However, inconsistencies were also observed in the comparison, such as a reduction of capacity for combinations of static and cyclic loads where the interaction diagram suggested “stable” behavior, and an increase in capacity for combinations where the diagram suggested “unstable” behavior. Other observations and implications of the centrifuge results are discussed. Inconsistencies between expected and observed response, such as that mentioned above, demonstrated a lack of full understanding on the complex mechanisms concerning the cyclic stability of tension piles. An axisymmetric finite-element model was developed in OpenSees (McKenna et al., 2010) to help understand the mechanisms affecting the evolution of the axial response (i.e., capacity, stiffness, and pullout rate) under different load combinations of static and cyclic loads on tension piles. The 2004 Dafalias and Manzari bounding surface plasticity model was used for the response of the soil. Five loading stages were performed to simulate this axial problem: confinement, installation by cylindrical cavity expansion and downward shear, static tensile shearing, cyclic shearing, and monotonic pullout. Results from the numerical analysis demonstrated the dependence of the evolution of axial response on the magnitudes of the static and cyclic shear stresses, and the number of applied cycles. Specifically, the analysis suggested the possibility for increase in tensile capacity and stiffening of the soil-pile stiffness for some load combinations, which is typically not considered in design. Other mechanisms and observations, as well as practical implication on current design, are presented.
Experimental Vibration Analysis For Civil Engineering Structures
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Author : Maria Pina Limongelli
language : en
Publisher: Springer Nature
Release Date : 2023-09-02
Experimental Vibration Analysis For Civil Engineering Structures written by Maria Pina Limongelli and has been published by Springer Nature this book supported file pdf, txt, epub, kindle and other format this book has been release on 2023-09-02 with Technology & Engineering categories.
This volume presents peer-reviewed contributions from the 10th International Conference on Experimental Vibration Analysis for Civil Engineering Structures (EVACES), held in Milan, Italy on August 30-September 1, 2023. The event brought together engineers, scientists, researchers, and practitioners, providing a forum for discussing and disseminating the latest developments and achievements in all major aspects of dynamic testing for civil engineering structures, including instrumentation, sources of excitation, data analysis, system identification, monitoring and condition assessment, in-situ and laboratory experiments, codes and standards, and vibration mitigation. The topics included but were not limited to: damage identification and structural health monitoring; testing, sensing and modeling; vibration isolation and control; system and model identification; coupled dynamical systems (including human–structure, vehicle–structure, and soil–structure interaction); and application of advanced techniques involving the Internet of Things, robot, UAV, big data and artificial intelligence.
Experimental And Numerical Study Of A Vertical Axis Tidal Turbine Performance
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Author :
language : en
Publisher:
Release Date : 2017
Experimental And Numerical Study Of A Vertical Axis Tidal Turbine Performance written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with categories.
Experimental And Numerical Investigations On The Collision Between Offshore Wind Turbine Support Structures And Service Vessels
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Author : S R Cho (B S Seo, B C Cerik and H K Shin)
language : en
Publisher:
Release Date : 2013
Experimental And Numerical Investigations On The Collision Between Offshore Wind Turbine Support Structures And Service Vessels written by S R Cho (B S Seo, B C Cerik and H K Shin) and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with Accidents categories.
Seismic Loading For Fast
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Author : M. A. Asareh
language : en
Publisher:
Release Date : 2012
Seismic Loading For Fast written by M. A. Asareh and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with Earthquakes categories.
As more wind farms are constructed in seismically active regions, earthquake loading increases in prominence for design and analysis of wind turbines. Early investigation of seismic load tended to simplify the rotor and nacelle as a lumped mass on top of the turbine tower. This simplification allowed the use of techniques developed for conventional civil structures, such as buildings, to be easily applied to wind turbines. However, interest is shifting to more detailed models that consider loads for turbine components other than the tower. These improved models offer three key capabilities in consideration of base shaking for turbines: 1) The inclusion of aerodynamics and turbine control; 2) The ability to consider component loads other than just tower loads; and 3) An improved representation of turbine response in higher modes by reducing modeling simplifications. Both experimental and numerical investigations have shown that, especially for large modern turbines, it is important to consider interaction between earthquake input, aerodynamics, and operational loads. These investigations further show that consideration of higher mode activity may be necessary in the analysis of the seismic response of turbines. Since the FAST code is already capable of considering these factors, modifications were developed that allow simulation of base shaking. This approach allows consideration of this additional load source within a framework, the FAST code that is already familiar to many researchers and practitioners.