A time-domain model for predicting aerodynamic loads on a slender support structure for fatigue design

Chang, Byoung-Ky

doi:10.31274/rtd-180813-16799

Cited by 3 publications

(4 citation statements)

References 19 publications

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“…We show by means of simulations that the proposed estimator outperforms the standard KF in tracking the bending moment time history at critical locations of a tall and slender structure resembling the tower of a wind generator and, most importantly, that the proposed estimator provides significant improvements on the estimation accuracy of the number of threshold crossings, critical for fatigue prone structures subject to wind loading. In contrast with traditional methods for the assessment of fatigue damage on wind‐excited slender structures , the proposed algorithm does not require prior estimation of the wind loading, for example, in a wind tunnel test or any assumptions (or detailed analysis) of the wind and turbulence field in the proximity of the structure.…”

Section: Introductionmentioning

confidence: 99%

On-line monitoring of wind-induced stresses and fatigue damage in instrumented structures

Hernández

Bernal

Caracoglia

2012

Struct. Control Health Monit.

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SUMMARYThe use of sparse-measured response as a means to monitor stresses and fatigue damage throughout metal structures has been the subject of recent work by researchers in the field of vibration-based structural health monitoring. The basic premise is that by using measured structural response, one can improve upon purely stochastic estimates. The most recent applications found in the literature employ the Kalman filter as an estimator. In this paper, we propose a finite element model-based state estimator that can be implemented as a modified version of the finite element model of the system using corrective forces that are proportional to the measurements. In contrast with the standard Kalman filter, the proposed estimator explicitly accounts for spatial correlation and for the colored nature of the excitation through knowledge of its power spectral density. The approach is used to estimate the number of threshold crossings in the bending moment history of a simulated tall vertical structure subject to turbulent wind. It is shown that the proposed model-based estimator outperforms a standard Kalman filter.

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Section: Introductionmentioning

confidence: 99%

On-line monitoring of wind-induced stresses and fatigue damage in instrumented structures

Hernández

Bernal

Caracoglia

2012

Struct. Control Health Monit.

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“…As confirmed in a later study performed by Constantinescu et al [37], the truck passage was found to have a negligible contribution to fatigue [22,36,38]. The fatigue performance of high-mast, light poles was evaluated by Chang et al (2009 and 2010) through a long-term field monitoring program [39,40]. This study was then extended to evaluate aluminum DMS-support structures under thermal loads [41].…”

Section: Discussionmentioning

confidence: 87%

Vulnerability assessment of sign-support structures during transportation and in service

Arabi¹

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Dynamic Message Signs (DMSs) are increasingly used in highways as an effective means to communicate time-sensitive information with motorists. To ensure their long-term performance, it is critical to ensure that the truss structures that hold them can resist not only extreme loading events, but also fatigue induced by service loads. For this purpose, a comprehensive study has been conducted on the fatigue performance of this important category of structures. The current study evaluates the fatigue performance of DMS-support structures during transportation under road-induced excitations as well as throughout their service life under loads induced by environmental stressors. In the first section, fatigue analysis of these structures during transportation under road-induced excitations is conducted. To investigate this, a comprehensive field test and numerical study are conducted. For short-term monitoring, one span of a sign-support structure is instrumented. Additionally, detailed finite element simulations are conducted to obtain an in-depth understanding of the potential modes of damage under the road-induced excitations. The outcome of this study is expected to determine the extent of fatigue of DMS-support structures during transportation. In the second part, vulnerability assessment of these structures is investigated under thermal loads. For that purpose, two DMS-support structures located in Iowa are selected for long-term monitoring. Moreover, detailed finite element simulations are conducted to obtain an in-depth understanding of the expected extent of damage. Based on the results obtained from this study, the DMS-support structures are found to demonstrate a great performance under thermal loads, which strongly supports the recent transition from aluminum to steel truss structures. Finally, fatigue performance of DMS-support structures under the combined effects of diurnal temperature changes and natural wind excitations is investigated. Field monitoring has been vi paired with detailed FE simulations to understand the fatigue performance of DMS-support structures under multiple stressors. The current study is concluded with the investigation of wind directionality effects. The outcome of this study is expected to not only contribute to the long-term performance and safety of DMS-support structures, but also pave the way to implement similar multi-stressor perspectives for other transportation infrastructures in service. vii ACKNOWLEDGEMENT First of all, I would like to thank my thesis adviser Dr. Behrouz Shafei. His office door was always open whenever I had any trouble or question about my research. His support, guidance and ideas significantly helped to accomplish this work. I would also like to acknowledge Dr. Brent M. Phares and Dr. Ming-Chen Hsu as my committee members and I am gratefully indebted to their valuable comments on this thesis. I would also thank the Iowa Department of Transportation (DOT), which have funded this study as well as its several engineers who have helped in various parts o...

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“…Additionally, the effect of vibrations induced by vortex shedding must be accounted for (DNV/Risø, 2002). Vortex shedding is an aeroelastic phenomenon that involves the creation of "areas of negative pressures on either side of a structure normal to the wind direction" (Chang, 2007). Its occurrence is dependent on the cross section of the structure, as well as the design wind speed.…”

Section: Dynamic Effectsmentioning

confidence: 99%

“…However, it should be noted that at lower speeds (i.e., typical turbine operating speeds), it is possible that vortex shedding may occur, causing additional deflection of the tower, and therefore increased fatigue loading. Methods for investigation of vortex shedding have been developed by Chang (2007) for high-mast light poles, which could be extended to the towers that have been considered in this study. However, due to the lack of detailed turbine fatigue loading for a 328 ft (100 m) 3.0 MW turbine, it is not possible to determine how the occurrence of vortex shedding would affect the fatigue life of the tower.…”

Section: Dynamic Propertiesmentioning

confidence: 99%

An investigation of design alternatives for 328-ft (100-m) tall wind turbine towers

Lewin

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A time-domain model for predicting aerodynamic loads on a slender support structure for fatigue design

Cited by 3 publications

References 19 publications

On-line monitoring of wind-induced stresses and fatigue damage in instrumented structures

On-line monitoring of wind-induced stresses and fatigue damage in instrumented structures

Vulnerability assessment of sign-support structures during transportation and in service

An investigation of design alternatives for 328-ft (100-m) tall wind turbine towers

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