Seismic Load Analysis of Wind Turbines by Response Spectrum Approach

2011 ◽  
Author(s):  
Zhu Lei ◽  
Wang Yuanqing ◽  
Shi Yongjiu
Keyword(s):  
Wind Turbines ◽  
Response Spectrum ◽  
Seismic Load ◽  
Load Analysis

Seismic Design for Offshore Wind Farms – Lessons Learnt From the ACE Joint Industry Project

2021 ◽  
Author(s):  
Marcus Klose ◽  
Junkan Wang ◽  
Albert Ku
Keyword(s):  
Seismic Design ◽  
Wind Turbines ◽  
Wind Farms ◽  
The United States ◽  
Offshore Wind ◽  
Seismic Load ◽  
Support Structures ◽  
Offshore Wind Farms ◽  
Asian Pacific Region ◽  
The Impact

Abstract In the past, most of the offshore wind farms have been installed in European countries. In contrast to offshore wind projects in European waters, it became clear that the impact from earthquakes is expected to be one of the major design drivers for the wind turbines and their support structures in other areas of the world. This topic is of high importance in offshore markets in the Asian Pacific region like China, Taiwan, Japan, Korea as well as parts of the United States. So far, seismic design for wind turbines is not described in large details in existing wind energy standards while local as well as international offshore oil & gas standards do not consider the specifics of modern wind turbines. In 2019, DNV GL started a Joint Industry Project (JIP) called “ACE -Alleviating Cyclone and Earthquake challenges for wind farms”. Based on the project results, a Recommended Practice (RP) for seismic design of wind turbines and their support structures will be developed. It will supplement existing standards like DNVGL-ST-0126, DNVGL-ST-0437 and the IEC 61400 series. This paper addresses the area of seismic load calculation and the details of combining earthquake impact with other environmental loads. Different options of analysis, particularly time-domain simulations with integrated models or submodelling techniques using superelements will be presented. Seismic ground motions using a uniform profile or depth-varying input profile are discussed. Finally, the seismic load design return period is addressed.

On Categorization of Seismic Load As Primary or Secondary for Piping Systems With Hardening Capacity

2018 ◽  
Author(s):  
Pierre B. Labbé
Keyword(s):  
Natural Frequency ◽  
Response Spectrum ◽  
A Priori ◽  
Effective Stiffness ◽  
Linear Oscillator ◽  
Seismic Load ◽  
Wide Range ◽  
Non Linear ◽  
Piping Systems ◽  
Non Linear Oscillator

The concept of primary/secondary categorization is first reviewed and generalized for its application to a non-linear oscillator subjected to a seismic load. Categorizing the seismic load requires calculating the input level associated with the oscillator ultimate capacity and comparing it to the level associated with the plastic yield. To resolve this problem, it is assumed that the non-linear oscillator behaves like a linear equivalent oscillator, with an effective stiffness (or frequency) and an effective damping. However, as it is not a priori possible to predict the equivalent stiffness and damping, a wide range of possibilities is systematically considered. The input motion is represented by its conventional response spectrum. It turns out that key parameters for categorization are i) the “effective stiffness factor” (varying from 0 for perfect damage behaviour to 1 for elastic-perfectly plastic) and the slope of the response spectrum in the vicinity of the natural frequency of the oscillator. Effective damping and spectrum sensitivity to damping play a second order role. A formula is presented that enables the calculation of the primary part of a seismically induced stress as a function of both the oscillator and input spectrum features. The formula is also presented in the form of a diagram. This paper follows-up on a similar paper presented by the author at the PVP 2017 Conference [1]. The new development introduced here is that the oscillator exhibits hardening capacity, while no hardening was assumed in [1]. It appears that the conclusions are slightly modified but the trend is very similar to the non-hardening case. Regarding piping systems, it appears that even when experiencing large plastic strains under beyond design input motions, their observed effective frequency is very close to their natural frequency, decreasing only by a few percents (experimental data from USA, Japan and India are processed). These observations lead to the conclusion that the seismic load, or the seismically induced inertial seismic strains, should basically be regarded as secondary.

Fatigue-Ratcheting Behavior of 6 in Pressurized Carbon Steel Piping Systems Under Seismic Load: Experiments and Analysis

2017 ◽  
Vol 139 (6) ◽  
Author(s):  
A. Ravi Kiran ◽  
G. R. Reddy ◽  
P. N. Dubey ◽  
M. K. Agrawal
Keyword(s):  
Carbon Steel ◽  
Response Spectrum ◽  
Thickness Variation ◽  
Seismic Load ◽  
Frequency Change ◽  
Shake Table Tests ◽  
Numerical Studies ◽  
Piping Systems ◽  
Earthquake Load ◽  
Steel Piping

This article presents the experimental and numerical studies of fatigue-ratcheting in carbon steel piping systems under internal pressure and earthquake load. Shake table tests are carried out on two identical 6 in pressurized piping systems made of carbon steel of grade SA333 Gr 6. Tests are carried out using similar incremental seismic load till failure. Wavelet analysis is carried to evaluate frequency change during testing. The tested piping systems are analyzed using iterative response spectrum (IRS) method, which is based on fatigue-ratcheting and compared with test results. Effect of thickness variation in elbow on strain accumulation is studied. Excitation level for fatigue-ratcheting failure is also evaluated and the details are given in this paper.

Substructure Flexibility and Member-Level Load Capabilities for Floating Offshore Wind Turbines in OpenFAST

2019 ◽  
Author(s):  
Jason M. Jonkman ◽  
Rick R. Damiani ◽  
Emmanuel S. P. Branlard ◽  
Matthew Hall ◽  
Amy N. Robertson ◽  
...  
Keyword(s):  
Rigid Body ◽  
Wind Turbines ◽  
Cost Effective ◽  
Offshore Wind ◽  
Functional Requirements ◽  
Global Response ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines ◽  
Load Analysis ◽  
Source Physics

Abstract OpenFAST is an open-source, physics-based engineering tool applicable to the load analysis of land-based and offshore wind turbines, including floating offshore wind turbines. The substructure for a floating wind turbine has historically been modeled in OpenFAST as a rigid body with hydrodynamic loads lumped at a point, which enabled the tool to predict the global response of the floating substructure but not the structural loads within its individual members. This limitation is an impediment to designing floating substructures — especially newer designs that are more streamlined, flexible, and cost-effective. This paper presents the development plan of new capabilities in OpenFAST to model floating substructure flexibility and member-level loads, including the functional requirements and modeling approaches needed to understand and apply them correctly.

scholarly journals Seismic performance evaluation of high-rise steel buildings dependent on wind exposures

2019 ◽  
Vol 11 (3) ◽  
pp. 168781401983511
Author(s):  
Seonwoong Kim
Keyword(s):  
Seismic Performance ◽  
Response Spectrum ◽  
Slenderness Ratio ◽  
Lateral Force ◽  
Lateral Load ◽  
Seismic Load ◽  
Strong Wind ◽  
Steel Buildings ◽  
High Rise ◽  
Moderate Seismicity

The lateral load-resisting system of high-rise buildings in regions of low and moderate seismicity and strong wind such as the typhoon in the Korean peninsula considers the wind load as the governed lateral force so that the practical structural engineer tends to skip the evaluation against the seismic load. This study is to investigate wind-designed steel diagrid buildings located in these regions and check the possibility of the elastic design of them out. To this end, first, the diagrid high-rise buildings were designed to satisfy the wind serviceability criteria specified in KBC 2016. Then, the response spectrum analyses were performed under various slenderness ratio and wind exposures. The analyses demonstrated the good seismic performance of these wind-designed diagrid high-rise buildings because of the significant over-strength induced by the lateral load-resisting system of high-rise buildings. Also, the analysis results showed that the elastic seismic design process of some diagrid high-rise buildings may be accepted based on slenderness ratios in all wind exposures.

Investigation on the Effect of Infilled Walls Utilizing Response Spectrum Analysis for Steel Staggered-Truss System

2012 ◽  
Vol 152-154 ◽  
pp. 34-39
Author(s):  
Qing Sheng Guo ◽  
Qing Shan Yang
Keyword(s):  
Spectrum Analysis ◽  
Earth Quake ◽  
Simulation Analysis ◽  
Response Spectrum ◽  
Steel Structure ◽  
3D Models ◽  
Structure Design ◽  
Seismic Load ◽  
Base Shear ◽  
Response Spectrum Analysis

Considering the structure type of the steel staggered-truss (SST) system, the effect of infilled walls will be major and need to be studied amply, some scientific design regulations need to be found for referrence. Based on two different 3D models considering or ignoring the stiffness of infilled walls (SIW), a numerical investigation is presented on the structural behaviors of the SST system utilizing the finite element 3D simulation analysis soft ware ETABS. The longitudinal structure is asymmetrical due to the SIW, it causes the torsion forces in the building. Comparing to the different results of response spectrum analysis, including storey drift and equivalent base shear under frequent earth quake and rare earth quake, some conclusions were made, including the capacity of the SST system under seismic load and the effect of the SIW for SST system. The increased base shear force factors due to the effect of the SIW were suggested for SST structure design, it is different from the other steel structure types.

Convex Model for a New Lateral Load Pattern of Pushover Analysis

2011 ◽  
Vol 243-249 ◽  
pp. 4013-4016
Author(s):  
Li Zhe Jia ◽  
Zhong Dong Duan
Keyword(s):  
Response Spectrum ◽  
Pushover Analysis ◽  
Fundamental Equation ◽  
Lateral Load ◽  
Seismic Load ◽  
Influence Coefficient ◽  
Convex Model ◽  
Load Pattern ◽  
Relationship Of ◽  
Strong Ground

The uncertainties of earthquake currently were not considered with the various lateral load patterns of pushover. The convex set theory, which requires much less information, is employed to model the uncertainties of the seismic influence coefficient maximum and the characteristic period of response spectrum. Then the convex analysis method is integrated into the fundamental equation of pushover, and the analytic relationship of lateral seismic load and top displacement of buildings is derived. The results of numerical example shows that the new lateral load pattern of pushover proposed in this research may effective simulate the uncertainties of strong ground motion.

Vertical and Horizontal Seismic Response Analyses of Long-Span and Single-Layer Spherical Lattice Shell Structure

2014 ◽  
Vol 602-605 ◽  
pp. 602-605
Author(s):  
Jin Sheng He ◽  
She Liang Wang
Keyword(s):  
Vibration Control ◽  
Shell Structure ◽  
Response Spectrum ◽  
Single Layer ◽  
Internal Force ◽  
Seismic Load ◽  
Seismic Responses ◽  
Long Span ◽  
Current Design ◽  
Lattice Shell

The dynamic characteristics of 80 m single-layer spherical lattice shell structure are analyzed to control its vibration under seismic load. Through the response spectrum curve of current design specification, the analyses for the vertical and horizontal seismic responses of the single-layer spherical lattice shell structure are made by CQC, and the displacement response of the nodes and internal force of the rods unit are calculated respectively. The calculation results show that the vertical and horizontal seismic responses of the long-span lattice shell structure are in great difference, and should be performed in vibration control at the same time, which could provide certain references for the seismic design and vibration control of single-layer spherical lattice shell structure.

scholarly journals Seismic Performance of a Tall Multi Storey Tower Connected by a large Podium

2019 ◽  
Vol 8 (2) ◽  
pp. 3545-3551
Keyword(s):  
Shear Force ◽  
Response Spectrum ◽  
Seismic Load ◽  
Response Spectrum Method ◽  
Structural Walls ◽  
Structural Wall ◽  
Spectrum Method ◽  
Unfavorable Effect ◽  
Tower Structure ◽  
Tower Height

The present work focus on the effect of podium structure of single tower structure connected by a common podium at the interface level under seismic load. For this purpose, the simulation model with varying tower height and podium height is created in the ETABs and it is analyzed for the equivalent static and response spectrum method. In this study, the effect on the top displacement of the tower connected with podium structure under equivalent static and response spectrum method of analysis is observed. The backstay forces that are developed to resist the lateral overturning actions at the interface when the lateral horizontal forces are transferred from the tower to the podium are studied. The unfavorable effect of podium on the shear force distribution at and above the interface level of the structural wall is observed. The positioning of the tower on the podium structure is found to be the reason for the differential displacement between the structural walls.

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