Simulation of Time Histories of Second-Order Wave Effects by Pseudo-Linear Transformation

1995 ◽  
Vol 117 (2) ◽  
pp. 78-84
Author(s):  
Y. Li
Keyword(s):  
Dynamic Response ◽  
Time History ◽  
Second Order ◽  
Hilbert Transforms ◽  
Structural Dynamic ◽  
Quadratic Transformation ◽  
Wave Effects ◽  
Time Histories ◽  
Component Wave ◽  
The Time Domain

Simulation of the time histories of second-order wave effects is often performed by quadratic transformation of a wave time history. By the present approach, the quadratic transformation of waves is approximated by linear combinations of the products of component wave time records and their Hilbert transforms. The computational efficiency is greatly enhanced. The efficient quadratic transformation of a time history is for the time domain solution of structural dynamic response, and can also be used as a post-processor of the frequency domain solution for obtaining statistic parameters of dynamic response.

Dynamic Response of a Semi-Submersible Floating Offshore Wind Turbine in Storm Condition

2012 ◽  
Vol 260-261 ◽  
pp. 273-278 ◽  
Author(s):  
Hai Tao Wu ◽  
Jin Jiang ◽  
Jing Zhao ◽  
Xiao Rong Ye
Keyword(s):  
Dynamic Response ◽  
Wind Turbine ◽  
Time History ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Offshore Platforms ◽  
Hydrodynamic Load ◽  
Floating Offshore Wind Turbine ◽  
The Time Domain ◽  
Storm Condition

The paper focuses on a semi-submersible floating offshore wind turbine (FOWT) and analyses its dynamic response in storm condition. The wind load is calculated based on wind block model; the hydrodynamic load is modeled using Potential Theory and Morison Equation. The time-domain dynamic response of the FOWT is simulated by SESAM software with duration of 3 hours. The performance of the FOWT is analyzed based on time history responses and response spectrums. The results show some unique characteristics that differ from offshore platforms and the analysis proofs that the performance is acceptable and the design is reliable.

F(P)SO Global Responses in the West of Africa Squall Environment

2005 ◽  
Author(s):  
Zhibin Zhong ◽  
Yong Luo ◽  
Dusan Curic
Keyword(s):  
Time Series ◽  
Wind Speed ◽  
Wind Direction ◽  
Time History ◽  
The Past ◽  
Transient Nature ◽  
Time Histories ◽  
The Time Domain ◽  
Water Depths ◽  
Tandem Offloading

Mooring design for F(P)SOs in West of Africa offshore environment is in many cases governed by the squall driven condition. In the past, the squall condition was typically analyzed by using the peak wind speed with associated wind direction. However, due to its inherent transient nature, the squall event formulated in the time history with varying wind speed and direction is more appropriate and could be potentially more critical for the mooring system design. This approach has been adopted in the design and analysis of recent F(P)SO mooring systems. The F(P)SOs are turret-moored in various water depths in offshore West of Africa. A series of squall time histories have been applied to predict the global responses of the F(P)SO in the time domain. Each squall time history, which provides a unique combination of wind speed and direction variations, is analyzed in five nominal directions covering a sector of 90 degrees from East to West. Squall time histories are also applied to analyze the tandem offloading operation. The results are compared with those of the conventional constant wind speed approach and a few interesting observations are made. The paper also provides some insights into the F(P)SO yaw motions, as well as their relations to the changing wind direction. Analysis results demonstrate that using the squall time series with changing wind speed and direction is more critical than the conventional constant wind speed approach in the tandem offloading scenario. It is therefore recommended that mooring analysis using squall time series should at least be used for the tandem offloading simulations.

Structural Surrogate Model and Dynamic Response Prediction with Consideration of Temporal and Spatial Evolution: An Encoder–Decoder ConvLSTM Network

2021 ◽  
pp. 2150140
Author(s):  
Hong Peng ◽  
Jingwen Yan ◽  
Ying Yu ◽  
Yaozhi Luo
Keyword(s):  
Dynamic Response ◽  
Surrogate Model ◽  
Structural Model ◽  
Short Term Memory ◽  
Time History ◽  
Response Prediction ◽  
Surrogate Models ◽  
Hybrid Network ◽  
Spatiotemporal Evolution ◽  
Structural Dynamic

In this paper, a new deep learning framework named encoding convolution long short-term memory (encoding ConvLSTM) is proposed to build a surrogate structural model with spatiotemporal evolution of structure, estimate the structural spatiotemporal state and predict the dynamic response under similar future dynamic load conditions. The main work of this study includes: (a) The spatiotemporal response tensor database is developed using discrete-time history data of structural dynamic response. (b) As an extension of LSTM, convolution operation is combined with LSTM network to construct structural surrogate model from the spatiotemporal evolution structural performance. (c) To enhance the anti-interference ability of structural surrogate models, a new three-layer encoding layer is added for denoising autoencoders of the hybrid network. The influence of building types and input noise on the accuracy and antinoise performance of the surrogate models are analyzed through the dynamic response prediction of a frame-shear wall, a cylindrical, and a spherical reticulated shell structure. As a testbed for the proposed network, a case study is performed on a laboratory stadium structure. The results demonstrate that the developed surrogate model can predict the structural dynamic response precisely with more under 30% noise interference.

Displacement Time Histories by Direct Numerical Integration of Acceleration Data

1991 ◽  
Author(s):  
M. L. Wang ◽  
S. R. Subia
Keyword(s):  
Time History ◽  
Shear Walls ◽  
Model Tests ◽  
Seismic Events ◽  
Scaled Model ◽  
Acceleration Data ◽  
Time Histories ◽  
Seismic Loadings ◽  
The Time Domain ◽  
Direct Numerical Integration

Abstract Acceleration measurements often provide the engineer with a means by which to determine the forces within dynamic structural systems. However for certain problems, information about the structural motion, the displacement-time history, may also be of interest. One such application deals with the evaluation of stiffness in reinforced concrete structures during seismic events. Scaled model tests of these events suggest that the stiffness of these structures often degrades drastically. The displacement response of these seismic events are required both for the development and evaluation of postulated structural stiffness models. This paper discusses the processing of acceleration data from scaled model tests to obtain displacement-time histories for low aspect shear walls subject to simulated seismic loadings. Displacement histories obtained in the time domain are compared with those produced using a frequency domain system identification analysis.

scholarly journals Integrating a Hive Triangle Pattern with Subpixel Analysis for Noncontact Measurement of Structural Dynamic Response by Using a Novel Image Processing Scheme

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Yung-Chi Lu ◽  
Shih-Lin Hung ◽  
Tzu-Hsuan Lin
Keyword(s):  
Image Processing ◽  
Digital Image Correlation ◽  
Dynamic Response ◽  
Digital Image ◽  
Time History ◽  
Image Correlation ◽  
Estimation Accuracy ◽  
Structural Dynamic ◽  
Processing Scheme ◽  
Noncontact Measurement

This work presents a digital image processing approach with a unique hive triangle pattern by integrating subpixel analysis for noncontact measurement of structural dynamic response data. Feasibility of proposed approach is demonstrated based on numerical simulation of a photography experiment. According to those results, the measured time-history displacement of simulated image correlates well with the numerical solution. A small three-story frame is then mounted on a small shaker table, and a linear variation differential transformation (LVDT) is set on the second floor. Experimental results indicate that the relative error between data from LVDT and analyzed data from digital image correlation is below 0.007%, 0.0205 in terms of frequency and displacement, respectively. Additionally, the appropriate image block affects the estimation accuracy of the measurement system. Importantly, the proposed approach for evaluating pattern center and size is highly promising for use in assigning the adaptive block for a digital image correlation method.

scholarly journals Dynamic Response of Self-Supported Power Transmission Tower Subjected to Wind Action

2018 ◽  
Vol 7 (4.35) ◽  
pp. 476
Author(s):  
Nur Hamizah Hamzah ◽  
Fathoni Usman ◽  
Mohd Yazee Mat Yatim
Keyword(s):  
Dynamic Response ◽  
Dynamic Analysis ◽  
Power Transmission ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Time History ◽  
Transmission Tower ◽  
Electrical Transmission ◽  
Structural Dynamic ◽  
Wind Action

A power transmission tower carries electrical transmission conductor at adequate distance from the ground. It must withstand all nature’s forces besides its self-weight. In structural analysis, natural frequency, mode shape and damping ratio are used to define the structural dynamic properties which relate to the basic structural features. This paper described the dynamic analysis including the modal and the time history analysis on each segment of the self-supported transmission tower to understand its dynamic responses subjected to wind action. The factors such as different height above ground, a different value of wind speed and different wind angle of attack were included in this study to see the influence of those factors towards dynamic response of the structure. The contribution of the wind towards the displacement of the structure is determined in this study by comparing the result obtained in a linear static analysis which considered the load combination without and with the presence of wind action. It was found that displacement using dynamic analysis is bigger than static linear analysis. The result illustrates that the studied factors gave a significant effect on the dynamic response of the structure and the findings indicate that dynamic analysis is vital in structural design.

scholarly journals Identification of Dynamic Loads Based on Second-Order Taylor-Series Expansion Method

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Xiaowang Li ◽  
Zhongmin Deng
Keyword(s):  
Series Expansion ◽  
Taylor Series ◽  
Time History ◽  
Taylor Series Expansion ◽  
Second Order ◽  
New Method ◽  
Dynamic Loads ◽  
Discrete Equation ◽  
System Response ◽  
Structural Dynamic

A new method based on the second-order Taylor-series expansion is presented to identify the structural dynamic loads in the time domain. This algorithm expresses the response vectors as Taylor-series approximation and then a series of formulas are deduced. As a result, an explicit discrete equation which associates system response, system characteristic, and input excitation together is set up. In a multi-input-multi-output (MIMO) numerical simulation study, sinusoidal excitation and white noise excitation are applied on a cantilever beam, respectively, to illustrate the effectiveness of this algorithm. One also makes a comparison between the new method and conventional state space method. The results show that the proposed method can obtain a more accurate identified force time history whether the responses are polluted by noise or not.

scholarly journals Dynamic Response Analysis of a Multiple Square Loops-String Dome under Seismic Excitation

Symmetry ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 2062
Author(s):  
Zhenwei Lin ◽  
Chao Zhang ◽  
Jucan Dong ◽  
Jianliang Ou ◽  
Li Yu
Keyword(s):  
Dynamic Response ◽  
Time History ◽  
Element Model ◽  
Internal Force ◽  
Seismic Excitation ◽  
Response Analysis ◽  
Seismic Structure ◽  
Force Response ◽  
Structural Dynamic ◽  
Seismic Arrays

The interaction between multiple loops and string cables complicates the dynamic response of triple square loops-string dome structures under seismic excitation. The internal connection between the multiple square loops-string cables and the grid beams was studies to provide a favorable reference for an anti-seismic structure. With a finite element model of the Fuzhou Strait Olympic Sports Center Gymnasium, established by SAP2000 software, the structural dynamic characteristic parameters were obtained first, and then this study adopted a time-history analysis method to study the internal force response of the cables and the roof grid beams of the multiple square loops-string dome (MSLSD) under three types of seismic array excitation. The influence of two factors, namely the seismic pulse and the near and far seismic fields, on the dynamic response of this structure was analyzed by three groups of different types of seismic excitation (PNF, NNF, PFF). As shown from the results, the first three-order vibration modes were torsional deformations caused by cables, the last five were mainly the overall roof plane vibration and antisymmetric vibration. Under the excitation of the three seismic arrays, the internal force responses of stay cables, square cables in the outer ring and the string cables were largest, while the maximum internal force response of the struts changed with the direction of seismic excitation. The largest internal force response of the roof grid beams occurred in local components such as BX3, BX7 and BY7, and the largest deformation of the beam nodes occurred in JX7, JX12 and JY4. In general, the seismic pulse and the near seismic field weakened the internal force response of the struts and cables but increased the internal force response and deformation of the dome beams, while the near and far seismic fields outweighed the seismic pulse. All the above provides an important reference for structural monitoring and seismic resistance.

Numerical Investigation of Vortex-Induced Vibration of a Marine SCR

2007 ◽  
Author(s):  
Alessandro A. de Lima ◽  
Julio R. Meneghini ◽  
Marcio Mourelle ◽  
Enrique Casaprima ◽  
Ricardo B. Flatschart
Keyword(s):  
Dynamic Response ◽  
Message Passing ◽  
Message Passing Interface ◽  
Vortex Method ◽  
Two Dimensional ◽  
The Finite Element Method ◽  
Discrete Vortex ◽  
Steel Catenary Riser ◽  
Time Histories ◽  
The Time Domain

In this paper the dynamic response and fatigue analysis of a marine SCR (Steel Catenary Riser) due to vortex shedding is numerically investigated. The riser is divided in two-dimensional sections along the riser length. The discrete vortex method (DVM) is employed for the assessment of the hydrodynamic forces acting on these two-dimensional sections. The hydrodynamic sections are solved independently, and the coupling among the sections is taken into account by the solution of the structure in the time domain by the finite element method implemented in ANFLEX code [1]. Parallel processing is employed to improve the performance of the method. A master-slave approach via MPI (Message Passing Interface) is used to exploit the parallelism of the present code. The riser sections are equally divided among the nodes of the cluster. Each node solves the hydrodynamic sections assigned to it. The forces acting on the sections are then passed to the master processor, which is responsible for the calculation of the displacement of the whole structure. The time histories of stress are employed to evaluate the damage as well as the life expectancy of the structure by the rainflow method to count the cycles in the dynamic response.

scholarly journals The Eigenfunction Method for Determining Displacement Time History in Structural Dynamic Analysis

2019 ◽  
Author(s):  
Bo Li ◽  
Mahesh M. Pandey ◽  
Yang Lu ◽  
Kao-Shan Dai
Keyword(s):  
Numerical Integration ◽  
Time History ◽  
Structural Dynamic ◽  
Acceleration Time ◽  
Acceleration Time Histories ◽  
Acceleration Data ◽  
Time Histories ◽  
Viable Approach ◽  
Eigenfunction Method ◽  
Displacement Information

In condition monitoring of structures, acceleration time histories are usually recorded due to ease of instrumentation. In cases where the information about a displacement time history is required, the acceleration data needs to be integrated to obtain the velocity and then the velocity needs to be integrated to obtain the displacements. However, the numerical integration of the acceleration data usually introduces an unrealistic drift component to the velocity as well as displacement. This paper presents an eigenfunction method to derive velocity and displacement time histories from a given acceleration time history. The paper analyzes displacements in two case studies using the numerical integration as well as the proposed eigenfunction method. It is concluded that the eigenfunction method is a viable approach to derive the displacement information from the acceleration data.

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