Optimizing height and porosity of roadway wind barriers for viaducts and bridges

Kozmar, Hrvoje; Procino, Lorenzo; Borsani, Alessandra; Bartoli, Gianni

doi:10.1016/j.engstruct.2014.09.029

Cited by 49 publications

(22 citation statements)

References 10 publications

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“…Generally, Bora is a very strong, commonly dry and always gusty wind, which significantly influences optimal functioning of transportation networks, the agriculture, local wind energy yield as well as the fatigue of energy structures (e.g. Kozmar et al 2012aKozmar et al , 2012bKozmar et al , 2014Kozmar et al , 2015. While previous geophysical and meteorological studies laid ground on the macro-and meso-scale features of the Bora, (Jurčec 1981, Smith 1987, Grubišić 2004, Grisogono and Belušić 2009, further work is necessary to fully elucidate Bora turbulence in a form usable for wind engineers.…”

Section: Introductionmentioning

confidence: 99%

Near-ground turbulence of the Bora wind in summertime

Lepri

Večenaj

Kozmar

et al. 2015

Journal of Wind Engineering and Industrial Aerodynamics

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Bora is a strong, temporally and spatially variable downslope wind that blows along the Eastern Adriatic Coast and many other dynamically similar places around the world. Bora mean velocity rarely exceeds 20 m/s, while its strong gusts create significant problems for engineering structures, traffic and agriculture. Previous meteorological and geophysical studies laid foundations on Bora large-and mesoscale motions, but further research is necessary to fully understand and resolve Bora turbulence in a form usable for engineers. In this study, unique high-frequency measurements, carried out simultaneously in three heights on a meteorological tower in the hinterland of the city of Split, Croatia, are analyzed for a single summertime Bora episode. Time histories and vertical profiles are studied for turbulence intensity, Reynolds shear stress and turbulence length scales in comparison with values recommended in major international wind engineering standards. Turbulence intensity and Reynolds shear stress proved to be not that sensitive to meandering of the mean wind velocity, as the observed values remain within the same range during the time record. This trend applies on mean wind velocities larger than 5 m/s, as for smaller velocities the spread of values increases considerably. Turbulence length scales are observed to increase with increasing mean wind velocity and vice versa. With increasing height from the ground, turbulence intensity and absolute Reynolds shear stress decrease, turbulence length scales increase, all in agreement with the atmospheric physics. However, while turbulence intensity, Reynolds shear stress and longitudinal turbulence length scales generally agree well with the values recommended in international standards for the respective terrain type,

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Section: Introductionmentioning

confidence: 99%

Near-ground turbulence of the Bora wind in summertime

Lepri

Večenaj

Kozmar

et al. 2015

Journal of Wind Engineering and Industrial Aerodynamics

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“…According to the results from wind tunnel experiments on a train–barrier–bridge system [ 14 , 15 ], a taller wind barrier with a lower porosity may provide a greater reduction in the mechanical load on the train caused by the crosswind, and therefore provide better shielding effects; however, the side force and overturning moment transferred to the bridge from the wind barrier are increased. Therefore, the design of wind barriers (e.g., porosity and height) can introduce different effects on the aerodynamic performance of trains and bridges.…”

Section: Introductionmentioning

confidence: 99%

Aerodynamic Performance of an Adaptive GFRP Wind Barrier Structure for Railway Bridges

Dai

Bai

et al. 2020

Materials

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Wind barrier structures on railway bridges are installed to mitigate the wind effects on travelling trains; however, they cause additional wind loads and associated aerodynamic effects on the bridge. An innovative concept was developed for a wind barrier structure in this study that used a glass–fibre–reinforced polymer (GFRP) that may deform properly when subjected to a crosswind. Such deformation then allows for wind to pass, therefore reducing the wind loads transferred to the bridge. Wind tunnel experiments were conducted on a 1/40-scale train and bridge models with the proposed GFRP barrier subjected to airflow at different speeds up to 20 m/s. The side-force and overturning-moment coefficients of both the train and the bridge were evaluated to characterise the aerodynamic effects. The results show that favourable side-force and overturning-moment coefficients of the train were provided by wind barriers taller than 10 cm. The aerodynamic coefficients of the train were not significantly affected by the airflow speeds; meanwhile, the overturning-moment coefficient of the bridge decreased with the increase in airflow speed due to smaller wind resistance of the barrier after deformation. A numerical analysis was conducted on both the reduced- and full-scale models of the train–barrier–bridge system and the results supported the findings obtained from the wind tunnel experiments.

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“…Other full-scale experimental techniques include the use of cup and sonic anemometers [47,48,61]. With regard to wind tunnel testing, particle tracking velocimetry (PTV) [62], flow visualisation of the commencement of sand particle motion [32], hot-wire anemometry [46,63] and particle image velocimetry (PIV) [49,50,[64][65][66] have been applied.…”

Section: Introductionmentioning

confidence: 99%

“…In consequence, there is no much information on the wind characteristics in downstream locations where catenary contact wires are typically located. Nevertheless, it is fair to mention that Kozmar et al [64,65] studied by means of PIV technique in a wind tunnel, the characteristics of the flow above a model bridge section equipped with windbreaks at the leading edge. These authors reported an increment on the wind velocity with the windbreak porosity.…”

Section: Introductionmentioning

confidence: 99%

“…They provided a characterisation based on hot-wire anemometry of the shelter effect determined as the velocity magnitude reduction. Besides Kozmar et al [64,65] and Kwon et al [39], several authors have focused the interest on the effect induced by a single windbreak placed at the leading edge. For instance, Guo et al [69] analysed the effect of the windbreak height and porosity on the aerodynamic coefficients of a static train model.…”

Section: Introductionmentioning

confidence: 99%

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Characterisation of cross-flow above a railway bridge equipped with solid windbreaks

Avila-Sanchez

López-García

Cuerva

et al. 2016

Engineering Structures

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The flow field above a two dimensional model of a railway bridge equipped with solid windbreaks is analysed in a wind tunnel. Particle image velocimetry (PIV) is used to measure the flow velocity in planes perpendicular to the bridge span. The mean velocity components, the two-component turbulent kinetic energy, the turbulence intensities of the velocity fluctuation components and the Reynolds shear stress above the bridge deck are presented. The flow patterns based on the streamlines of the average flow field are analysed. The inclusion of a windbreak produces a separation bubble, that is locked to the bridge deck due to presence of the leeward fence. Special attention is paid to the analysis of the flow field characteristics along the vertical profiles above the railway tracks. The inclusion of the windbreak leads both to an increase of the mean velocity and the turbulence intensity around the catenary contact wires. On the other hand, the flow in the region close to the bridge deck is slowed-down. The effect of the size of the final interrogation window used in the PIV analysis is considered, more particularly on the determination of the mean velocity and turbulence intensity. The results show that a decrease of the final interrogation window leads to an increase of the turbulence intensity when there are no wind protection devices installed on the bridge.

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Optimizing height and porosity of roadway wind barriers for viaducts and bridges

Cited by 49 publications

References 10 publications

Near-ground turbulence of the Bora wind in summertime

Near-ground turbulence of the Bora wind in summertime

Aerodynamic Performance of an Adaptive GFRP Wind Barrier Structure for Railway Bridges

Characterisation of cross-flow above a railway bridge equipped with solid windbreaks

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