Assessment of Stiffening Type of the Cutout in Tubular Wind Turbine Towers Under Artificial Dynamic Wind Actions

2015 ◽  
Vol 10 (4) ◽  
Author(s):  
Christoforos A. Dimopoulos ◽  
Konstantina Koulatsou ◽  
Francesco Petrini ◽  
Charis J. Gantes
Keyword(s):  
Wind Turbine ◽  
Structural Performance ◽  
Wind Loading ◽  
Finite Element Models ◽  
The Public ◽  
Dynamic Analyses ◽  
Time Histories ◽  
Wind Actions ◽  
Wind Turbine Towers ◽  
Nonlinear Dynamic Analyses

The effectiveness of alternative stiffening types of the cutout provided near the base of tubular steel wind turbine towers is assessed, taking into account the dynamic nature of wind loading. To that effect, artificial wind load time histories are first obtained using the public domain aero-elastic code FAST. Finite element models that have been previously validated by means of comparison with experimental results, are then used to carry out fully nonlinear dynamic analyses and compare strength and overall structural performance.

Fatigue Strength and Evaluation of Double–Mast Arm Cantilevered Sign Structures

2005 ◽  
Vol 1928 (1) ◽  
pp. 64-72 ◽  
Author(s):  
Xuejun Li ◽  
Timothy M. Whalen ◽  
Mark D. Bowman
Keyword(s):  
Fatigue Life ◽  
Base Plate ◽  
Analytical Investigation ◽  
Wind Loading ◽  
Finite Element Models ◽  
Critical Detail ◽  
Dynamic Analyses ◽  
Sign Structure ◽  
Stress Cycles ◽  
High Flexibility

Double–mast arm cantilevered sign structures are widely used in Indiana and in many other states. Because of the large sign area and relatively high flexibility, wind loading on these sign structures occasionally produces significant stress cycles. Cracking caused by fatigue damage may occur at several critical spots on the sign structures. An analytical investigation of the fatigue lives of the critical details in double–mast arm sign structures is discussed in this paper. An analytical procedure is introduced, and wind load selection and simulation are explained. Finite element models based on a prototype double–mast arm sign structure are described, and dynamic analyses and fatigue life results are presented. It was found that the post-to–base plate socket weld connection was the most critical detail and that variations in the fatigue life occurred because of differences in the wind environment at various sites.

Fatigue Assessment on Reverse–Balanced Flange Connections In Offshore Floating Wind Turbine Towers

2021 ◽  
Author(s):  
Tao Zou ◽  
Wenjie Liu ◽  
Mingxin Li ◽  
Longbin Tao
Keyword(s):  
Wind Turbine ◽  
Fatigue Damage ◽  
Deep Water ◽  
Wind Loading ◽  
Wave Forces ◽  
Local Geometry ◽  
Elastic Analysis ◽  
Wind Turbine Towers ◽  
Welding Joints ◽  
Offshore Floating Wind Turbine

Abstract Offshore floating wind turbines (FWTs) in deep water experience cyclic loadings from both environment and mechanical operations. For FWTs, the upper turbine and tower are mainly subjected to wind loading; and the floater is subjected to wave forces. It has been widely accepted that there is a strong coupling between the floater motions and the turbine forces. As the tower is placed between the upper wind turbine and the floater, both wind and wave loadings affect the cyclic forces on the tower. The construction of towers makes use of prefabricated segments. These prefabricated segments are bolted together with flanges at either end. The paper aims to investigate the axial hotspot stress on FWT’s tower base and analyze its induced fatigue damage at the welding joints around the flanges. A coupled aero-hydro-servo-elastic analysis is conducted to simulate the motion of FWTs. Then, the local welding joint along the reverse-balanced flange connection is modeled to consider the influence of local geometry. At last, the hourly fatigue damages at four locations over the tower base section are compared.

DYNAMIC ANALYSIS OF WIND TURBINE TOWERS UNDER RANDOM WIND LOADING

2019 ◽  
Author(s):  
Lucas Foschiera ◽  
Herbert Gomes ◽  
Dodani Renan de Morais
Keyword(s):  
Dynamic Analysis ◽  
Wind Turbine ◽  
Wind Loading ◽  
Wind Turbine Towers

Structure-Specific Scalar Intensity Measures for Near-Source and Ordinary Earthquake Ground Motions

2007 ◽  
Vol 23 (2) ◽  
pp. 357-392 ◽  
Author(s):  
Nicolas Luco ◽  
C. Allin Cornell
Keyword(s):  
Ground Motions ◽  
Linear Regression Analysis ◽  
Structural Performance ◽  
Intensity Measures ◽  
Earthquake Ground Motions ◽  
Long Period ◽  
Earthquake Records ◽  
Dynamic Analyses ◽  
Nonlinear Dynamic Analyses ◽  
A Site

Introduced in this paper are several alternative ground-motion intensity measures ( IMs) that are intended for use in assessing the seismic performance of a structure at a site susceptible to near-source and/or ordinary ground motions. A comparison of such IMs is facilitated by defining the “efficiency” and “sufficiency” of an IM, both of which are criteria necessary for ensuring the accuracy of the structural performance assessment. The efficiency and sufficiency of each alternative IM, which are quantified via (i) nonlinear dynamic analyses of the structure under a suite of earthquake records and (ii) linear regression analysis, are demonstrated for the drift response of three different moderate- to long-period buildings subjected to suites of ordinary and of near-source earthquake records. One of the alternative IMs in particular is found to be relatively efficient and sufficient for the range of buildings considered and for both the near-source and ordinary ground motions.

Reliability Analysis of Seismic Isolation in Retrofitting of Simply Supported Bridges

2016 ◽  
Vol 847 ◽  
pp. 391-400
Author(s):  
Luigi Petti ◽  
Alessio Lodato ◽  
Angelo Mammone
Keyword(s):  
Seismic Isolation ◽  
Fragility Curves ◽  
Seismic Intensity ◽  
Finite Element Models ◽  
Design Strategies ◽  
Limit States ◽  
Damage Level ◽  
Simply Supported ◽  
Dynamic Analyses ◽  
Nonlinear Dynamic Analyses

The paper investigates the reliability of simply supported bridges, retrofitted or less with seismic isolation, by means of fragility curves, which represent the probability of reaching a certain damage level for an assigned seismic intensity. Taking advantage of the Multi Stripes methodology, several nonlinear dynamic analyses of a multi-span bridge representing the existing ones in Italy built in the 60 ' characterized by means of non linear finite element models in different design configurations of seismic retrofit have been carried out, in order to obtain the fragility functions.The obtained results allow to assess the isolation retrofit strategies effectiveness to mitigate the seismic risk of simply supported bridges, highlighting the influence of different design strategies on the probability of exceeding the limit states considered.

Nonlinear Response of Wind Turbines Under Wind and Seismic Excitations With Soil–Structure Interaction

2015 ◽  
Vol 10 (4) ◽  
Author(s):  
Evangelos J. Sapountzakis ◽  
Ioannis C. Dikaros ◽  
Andreas E. Kampitsis ◽  
Angeliki D. Koroneou
Keyword(s):  
Wind Turbine ◽  
Soil Structure ◽  
Nonlinear Dynamic Analysis ◽  
Axial Loading ◽  
Soil Surface ◽  
Variable Cross Section ◽  
Wind Loading ◽  
Variable Cross ◽  
Wind Turbine Tower ◽  
Time Histories

The objective of this paper is to present an efficient beam formulation based on the boundary element method (BEM), for the nonlinear dynamic analysis of wind turbine towers of variable cross section founded either on surface or on monopile foundation system. The whole structure may undergo moderately large displacements, taking into account the effect of soil–structure kinematic and inertia interaction. The tower is subjected to the combined action of arbitrarily distributed or concentrated transverse wind loading as well as to seismic excitation together with axial loading arising from the self-weight of the tower and the mechanical parts. The Blade element momentum theory is taken into consideration in order to produce the wind load time histories, while the site seismic response is obtained through one dimensional shear wave propagation analysis. The soil–surface foundation system is formulated as equivalent lateral and rotational springs, while the case of monopile system is treated as a prismatic beam on elastic foundation assigning the corresponding springs and dashpots along its length. An extensive case study is carried out on a wind turbine tower–foundation system employing the generated wind velocity time histories and recorded earthquake accelerograms, providing insight to several structural phenomena. The results of the proposed model are compared wherever possible with those obtained from a commercial finite elements software package, illustrating the validity and the efficiency of the developed method. From the obtained results, the strong influence of the nonlinear effects on the dynamic response of the wind turbine tower is verified.

Wind load response of offshore wind turbine towers with fixed monopile platform

2016 ◽  
Vol 158 ◽  
pp. 122-138 ◽  
Author(s):  
M. Feyzollahzadeh ◽  
M.J. Mahmoodi ◽  
S.M. Yadavar-Nikravesh ◽  
J. Jamali
Keyword(s):  
Wind Turbine ◽  
Wind Load ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Load Response ◽  
Wind Turbine Towers

scholarly journals Verification of the Structural Performance of Textile Reinforced Reactive Powder Concrete Sandwich Facade Elements

2019 ◽  
Vol 9 (12) ◽  
pp. 2456 ◽  
Author(s):  
Mathias Flansbjer ◽  
Natalie Williams Portal ◽  
Daniel Vennetti
Keyword(s):  
Structural Model ◽  
Structural Performance ◽  
Wind Loading ◽  
Experimental Program ◽  
Reactive Powder Concrete ◽  
Uniaxial Tensile ◽  
Material Development ◽  
Pull Out ◽  
Glass Fiber Reinforced ◽  
Reactive Powder

As a part of the SESBE (Smart Elements for Sustainable Building Envelopes) project, non-load bearing sandwich elements were developed with Textile Reinforced Reactive Powder Concrete (TRRPC) for outer and inner facings, Foam Concrete (FC) for the insulating core and Glass Fiber Reinforced Polymer (GFRP) continuous connectors. The structural performance of the developed elements was verified at various levels by means of a thorough experimental program coupled with numerical analysis. Experiments were conducted on individual materials (i.e., tensile and compressive tests), composites (i.e., uniaxial tensile, flexural and pull-out tests), as well as components (i.e., local anchorage failure, shear, flexural and wind loading tests). The experimentally yielded material properties were used as input for the developed models to verify the findings of various component tests and to allow for further material development. In this paper, the component tests related to local anchorage failure and wind loading are presented and coupled to a structural model of the sandwich element. The validated structural model provided a greater understanding of the physical mechanisms governing the element’s structural behavior and its structural performance under various dead and wind load cases. Lastly, the performance of the sandwich elements, in terms of composite action, was shown to be greatly correlated to the properties of the GFRP connectors, such as stiffness and strength.

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