Theory of Bridge Aerodynamics

Strømmen, Einar N.

doi:10.1007/978-3-642-13660-3

Cited by 57 publications

(39 citation statements)

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“…Figure 7 supports the argument that the Weibull distribution can express wind speed data well. This conclusion also can be supported by the fact that the Weibull distribution is one of the most popular distribution types in wind engineering [29,30]. However, it cannot be generalized for all geometric sites because wind speed is a very sensitive characteristic and, generally, strongly influenced by topographic and thermal effects [30].…”

Section: Wind Speed Datamentioning

confidence: 76%

“…According to the U.S. Insurance Institute for Highway Safety (IIHS), ESC has reduced fatal crash involvement risk by 33% from 1999 to 2008 [3], which indicates the remarkable contribution of the electronic safety system. However, although such safety systems have been widely equipped since the early 2000s, FARS shows that 32,885 people were still killed in 30,196 fatal crashes on the U.S. roadway system in 2010. This suggests that the problem cannot be resolved only by the development of advanced vehicle systems and that we should also focus on the fundamental causes of vehicle accidents.…”

Section: Introductionmentioning

confidence: 98%

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Reliability-Based Vehicle Safety Assessment and Design Optimization of Roadway Radius and Speed Limit in Windy Environments

Shin

Lee

2014

Journal of Mechanical Design

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This paper presents a reliability-based analysis of road vehicle accidents and the optimization of roadway radius and speed limit design based on vehicle dynamics, mainly focusing on windy environments. The performance functions are formulated as failure modes of vehicle rollover and sideslip and are defined on a finite set of basic variables with probabilistic characteristics, so-called random variables. The random variables are vehicle speed, steer angle, tire-road friction coefficient, road bank angle, and wind speed. The probability of accident was evaluated using the first-order reliability method (FORM) and numerical studies were conducted using a single-unit truck model. The analysis demonstrates that wind is a significant factor when assessing vehicle safety on roads, and probabilistic studies such as reliability-based design optimization (RBDO) are necessarily required to enhance vehicle safety in windy environments. Accordingly, design optimization of roadway radius and speed limit was conducted, and new designs were proposed satisfying the target reliability. This study suggests that probabilistic mechanics and theory can be of value for analysis and design of wind-related vehicle safety.

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Section: Wind Speed Datamentioning

confidence: 76%

Section: Introductionmentioning

confidence: 98%

Reliability-Based Vehicle Safety Assessment and Design Optimization of Roadway Radius and Speed Limit in Windy Environments

Shin

Lee

2014

Journal of Mechanical Design

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“…(19)), as described in Ref. [19], where N is the number of included frequency components, Aw is the fre quency step and phase angle 9 is a random value between -n and n N M{t) = Y \/2S M(®*)Aa> cos(co*t + 0k)…”

Section: Flexible Response To the Direct Wind Forcesmentioning

confidence: 99%

Frequency Versus Time Domain Fatigue Analysis of a Semisubmersible Wind Turbine Tower

Kvittem

Moan

2014

Journal of Offshore Mechanics and Arctic Engineering

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The current paper deals with a study of a semisubmersible wind turbine (WT), where short-term tower base bending moments and tower fatigue damage were estimated by a frequency domain (FD) method. Both a rigid structure assumption and a generalized degree-of-freedom (DOF) model for including the first flexible mode of the turbine tower were investigated. First, response to wind and wave loads was considered separately, then superposition was used to find the response to combined wind and wave loading. The bending moments and fatigue damage obtained by these methods were compared to results from a fully coupled, nonlinear time domain (TD) analysis. In this study a three column, catenary moored semisubmersible with the NREL 5 MW turbine mounted on one of the columns was modeled. The model was inspired by the WindFloat concept. The TD simulation tool used was Simo-Riflex-AeroDyn from Marintek and CeSOS. The FD method gave a good representation of the tower base bending moment histories for wave-only analyses, for the moderate sea states considered in these analyses. With the assumption that the structure is completely rigid, bending moments were underestimated, but including excitation of the elastic tower and blades, improved the results. The wind-induced low-frequency bending moments were not captured very well, which presumably comes from a combination of nonlinear effects being lost in the linearization of the thrust force and that the aerodynamic damping model was derived for a fixed turbine. Nevertheless, standard deviations of the bending moments were still reasonable. The FD model captured the combined wind and wave analyses quite well when a generalized coordinates model for wind excitation of the first bending mode of the turbine was included. The FD fatigue damage predictions were underestimated by 0–60%, corresponding to discrepancies in standard deviations of stress in the order of 0–20%.

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“…The mean and buffeting forces refer to the load due to the mean and fluctuating wind velocity, which can be calculated based on quasi-steady theory [39]. The effect of frequency-dependent aerodynamic admittance on the buffeting force is not considered in this paper.…”

Section: Mean and Buffeting Forcesmentioning

confidence: 99%

Prediction of long-term extreme load effects due to wind for cable-supported bridges using time-domain simulations

Yang

Øiseth

Næss

et al. 2017

Engineering Structures

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Many long-span bridges that are slender and susceptible to wind-induced vibrations are currently under construction all over the world. As nonlinear structural behavior and nonlinear displacementdependent wind loads become of higher importance, time-domain methods are commonly applied instead of frequency-domain approaches. This paper discusses how rational functions, fitted to aerodynamic derivatives, can be converted to a state-space model to transform the frequencydependent aerodynamic forces into the time domain. A user element has been implemented in ABAQUS to include the self-excited forces in the dynamic analysis. The flutter stability limit and buffeting response of the Hardanger Bridge have been calculated in a comprehensive case study to illustrate the performance of the presented methodology. The Average Conditional Exceedance Rate method is used to estimate long-term extreme load effects. A simplified full long-term method that ignores wind velocities which contribute little to the long-term extreme values is introduced to reduce the required computational effort. The long-term predictions are also compared with results obtained using a short-term approach and it is concluded that the long-term extreme load effects are approximately 20% higher than the short-term extreme values.

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Theory of Bridge Aerodynamics

Abstract: The use of general descriptive names, registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use.

Cited by 57 publications

References 0 publications

Reliability-Based Vehicle Safety Assessment and Design Optimization of Roadway Radius and Speed Limit in Windy Environments

Reliability-Based Vehicle Safety Assessment and Design Optimization of Roadway Radius and Speed Limit in Windy Environments

Frequency Versus Time Domain Fatigue Analysis of a Semisubmersible Wind Turbine Tower

Prediction of long-term extreme load effects due to wind for cable-supported bridges using time-domain simulations

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