2024 - 2025
Ole Oiseth
Girma Bitsuamlak
Aksel Fenerci
Oyvind Wiig Petersen
Sebastian Knedahl Hansen
2024 - 2025
Aerodynamic performance of bridge decks subjected to downburst-like non-stationary outflows
AEROBURST
Dataset Description
This research investigates non-synoptic, non-stationary downburst-like wind effects on long-span bridge sections. The study is motivated by field observations of unusually strong responses of long span bridges in Norway (Petersen et al., 2020) and the United Kingdom (Owen et al., 2020) under winds exhibiting transient behaviour. To get an insight on the differences between the effects of synoptic and downburst-like winds on flexible bridges, static and dynamic section model tests were conducted under combined straight and impinging jet outflow winds simulated at the WindEEE Dome. under. This dataset consists of measurements of wind profiles used for testing the models, surface pressure measurements of the static section model, and vibration and force measurements of the dynamic section model.
Specimens
1. Vertical Profile Development (Rack 1)
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ABL, downburst-like, and the combination of downburst-like and ABL wind simulations were measured in a near-empty chamber. Turbulent Flow Instruments (TFI) Cobra Probes were used to characterize wind profiles and were mounted on to a vertical rack at heights of 5, 7.5, 10.0, 15.0, 20, 30.0, 40.0, and 50 cm above the ground surface. The location of the vertical profile varied between the experiments outlined below.
1. Downburst-like Wind Profiling
An impinging-jet style downburst is generated at the WindEEE dome through the release of pressure from a plenum above the testing chamber. Like the ABL measurements, 3-D point measurements were taken to characterize the velocity profiles for downbursts. For the downburst simulations, two parameters were varied: the strength of the impinging jet flow and the position of the bell mouth (r_jet) in the WindEEE dome.
The vertical rack was positioned at a radial distance from the center of the turntable, rm = 320 cm, and with model angular position, φ = 180 degrees. The bell mouth position r_jet = -192, -128, -64, 0, 64, and 128 cm from the centre of the turntable. These positions achieved r/D ratios of 1.6, 1.4, 1.2, 1, 0.8, and 0.6. These measurements aim to provide detailed characteristics of the wind profile as it develops radially.
Instrumentation
The instantaneous wind velocities of the uniform smooth flows were captured utilizing eight synchronized, TFI cobra probes. Seven of the probes were installed on the vertical rack at the described heights. The eighth probe was used to measure the reference velocity. The cobra devices capture u-, v , and w- components along with reference pressure in separate channels on the TFI data acquisition system.
2. Atmospheric Boundary Layer (ABL) Flow Profiling
The 60-fan wall located on one side of the hexagonal shaped WindEEE test chamber was used to generate the various ABL flows for this experiment. During the experiment, 3-D point measurements were taken to characterize the velocity profiles for numerous uniform smooth flow wind speeds.
The vertical rack (where the measurements of the profile are taken) was positioned at radial distance (rm) of 320 cm and at an azimuth angle φ = 180 degrees. The reference measurements were taken at a height of 50 cm.
Instrumentation
Similar instrumentation was used as described in S1.E1.
3. Combination Downburst-like and ABL Wind Profiling
In combination with the described downburst simulation in ‘S1. E2.’, these impinging-jets can be run simultaneously with the 60-fan wall (described in ‘S1. E1’) to achieve ABL and downburst-like flow combinations. During this experiment, 3-D point measurements were taken to characterize the velocity profile for a downburst with ABL wind.
The vertical rack was positioned at a radial distance from the center of the turntable (rm) at 320 cm and with φ=180, and 210 degrees. The bell mouth position r_jet = 0 cm from the centre of the turntable.
Instrumentation
Similar instrumentation was used as described in S1.E1.
2. Horizontal Profile Development (Rack 2)
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ABL, downburst-like, and the combination of downburst-like and ABL wind simulations were measured in a near-empty chamber. Turbulent Flow Instruments (TFI) Cobra Probes were used to characterize wind profiles and were mounted on to a horizontal rack at heights of 10, and 20 cm above the ground surface. The probes were spaced relative to the centre of the rack perpendicular to the ABL wind direction at distances of -60, -45, -30, -15, -7.5, 0, 15, and 30 cm. The location of the horizontal profile varied between the experiments outlined below.
1. Downburst-like Wind Profiling
An impinging-jet style downburst is generated at the WindEEE dome through the release of pressure from a plenum above the testing chamber. Like the ABL measurements, 3-D point measurements were taken to characterize the velocity profiles for downbursts. For the downburst simulations, two parameters were varied: the strength of the impinging jet flow and the position of the bell mouth (r_jet) in the WindEEE dome.
The vertical rack was positioned at a radial distance from the center of the turntable (rm) at 320 cm and with φ=180 degrees. The bell mouth position r_jet = -192, -128, -64, 0, 64, and 128 cm from the centre of the turntable. These positions achieved r/D ratios of 1.6, 1.4, 1.2, 1, 0.8, and 0.6. These measurements aim to provide detailed characteristics of the wind profile as it develops radially.
Instrumentation
The instantaneous wind velocities of the uniform smooth flows were captured utilizing eight synchronized, TFI cobra probes. The eight probes were installed on the horizontal rack at the described heights and horizontal positions. The cobra devices capture u-, v , and w- components along with reference pressure in separate channels on the TFI data acquisition system.
2. Atmospheric Boundary Layer (ABL) Flow Profiling
The 60-fan wall located on one side of the hexagonal shaped WindEEE test chamber was used to generate the various ABL flows for this experiment. During the experiment, 3-D point measurements were taken to characterize the velocity profiles for numerous uniform smooth flow wind speeds.
The vertical rack (where the measurements of the profile are taken) was positioned at radial distance (rm) of 320 cm and at an azimuth angle φ = 180 degrees.
Instrumentation
Similar instrumentation was used as described in S2.E1.
3. Combination Downburst-like and ABL Wind Profiling
In combination with the described downburst simulation in ‘S2. E2.’, these impinging-jets can be run simultaneously with the 60-fan wall (described in ‘S2. E1’) to achieve ABL and downburst-like flow combinations. During this experiment, 3-D point measurements were taken to characterize the velocity profile for a downburst with ABL wind.
The vertical rack was positioned at a radial distance from the center of the turntable (rm) at 320 cm and with φ=180, and 210 degrees. The bell mouth position r_jet = 0 cm from the centre of the turntable.
Instrumentation
Similar instrumentation was used as described in S2.E1.
3. 1-100 Scale Static Section Pressure Model
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This specimen was a rigid 1-100 scale section of a bridge inspired by the Hardanger Bridge (HB) in Norway. HB is chosen as the UG has extensive experience on classical wind tunnel testing of the section and possesses full-scale measurements of non-stationary events that are relevant for the proposed project. The bridge cross-section is simplified as hexagonal prism with chord width of 18.3 cm, and thickness of 3.25 cm. The section model is 1.5 m (7.5 times its chord width) long in the spanwise direction, The bridge geometry is further described in the documentation and diagrams contained in this dataset. The bridge construction was made as a cavity, a cap, and supporting rods to house the pressure tubing and support the weight of the model along the span. The angle of attack (a) of the bridge was made adjustable using bearings mounted at each support ends. The model has 348 pressure taps distributed over its external surfaces as shown in the tap layout drawing. Pressure tap coordinates are available to correlate instantaneous measurements with locations covering the model. The specimen was tested under synoptic and non-synoptic wind simulations at WindEEE (e.g., ABL, Downburst-like, and ABL-Downburst Combination flows).
1. Straight Wind Loading
This test involved the bridge section model subjected to ABL flow at a wind speed of approximately 10 m/s. The model was positioned 320 cm downwind from the center of the turntable facing the 60-fan wall (rm = 3.2 m, φ = 180°). The model angle of attack was tested at angles δ = ±5°, ±3°, and 0°, and at heights of 10 cm and 20 cm above the ground surface.
Instrumentation
The 348 pressure taps are connected to PSI pressure scanners using clear PV tubes that were contained within the bridge model. Digital differential pressure values were acquired using PSI’s DAQ system at a sampling rate of 500 Hz. The measured surface pressures were referenced relative to a pressure port inside a static reference box located in the lower chamber. Additional pressure measurements were made for referencing, including the test chamber wall, upper plenum wall, and the total and static pressure of a pitot tube. Reference velocity measurements were captured using one ‘Straight’ TFI Cobra Probe, located in the same position as S1.E1.
2. Downburst Wind Loading
This experiment involves testing the static section model under various simulated downburst flow profiles and strengths. The model was positioned 320 cm downwind from the center of the turntable facing the 60-fan wall (rm = 3.2 m, φ = 180°). The model was tested at geometric angles of attack a = ±5°, ±3°, and 0°, and at heights of 10 cm and 20 cm above the ground surface at r/D = 1.0. In addition, the radial position of the impinging jet (rjet) was varied relative to the model to achieve r/D = 0.6, 0.8, 1.2, 1.4, and 1.6, only the downburst strength was varied for these positions, the angle of attack a = 0°.
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Instrumentation
Similar instrumentation was used as described in S3.E1.
3. Combined Downburst and ABL Loading
This test involved the static section model subjected to various downburst simulations involving combinations of impinging jet outflows and an ABL head wind of approximately 4-5m/s, generated from the 60-fan wall. The model was positioned 320 cm radially from the center of the turntable at angles of φ = 180°, and 210°. During the φ = 180° position the model was tested with angles of attack of a = ±5°, ±3°, and 0°, and at heights of 10 cm and 20 cm above the ground surface. During the φ = 210° position the model was tested with angles of attack of a = 0° for heights of 10 and 20 cm. All tests in these configurations were captured with the impinging jet at a position of r/D = 1.0 relative to the model.
Instrumentation
Similar instrumentation was used as described in S3.E1. However, at model position φ = 210°, the reference cobra probe followed a similar positional change, while being directed at the centre of the impinging jet the probe was placed at φ = 210°, r = 320 cm, and a height of 50 cm.
4. 1-100 Scaled Dynamic Bridge Section Model
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This specimen was a dynamic 1-100 scale section of a bridge inspired again by the Hardanger Bridge (HB) in Norway. The bridge geometry is like that of Specimen 3; however, the construction was different. The dynamic bridge model was required to have a mass per unit length of 1.28 kg/m, a mass moment of inertia of 0.00426 kg/m, a horizontal frequency of 2.5 Hz, a vertical frequency of 7 Hz, and a torsional frequency of 18 Hz. The mass and moments of inertia were achieved by constructing this model out of a composition of high-density polypropylene foam, a carbon fiber rod, and various stainless-steel rods. The model was suspended in custom made test rig utilizing tension springs of various stiffness and taut strings which attached to the 3D-printed end plates and steel rods embedded in the foam cladding, respectively. The end plates and spring stiffnesses were specifically selected to provide the model with its design frequencies. The model was suspended 20 cm above the floor and had an angle of attack of a= 0°. The specimen was tested under simulated synoptic and non-synoptic winds at WindEEE (e.g., ABL, Downburst-like, and combined ABL-Downburst flows).
1. Straight Wind Effects
This test involved the dynamic section model subjected to ABL flow at various wind speeds. The model was positioned 320 cm downwind from the center of the turntable facing the 60-fan wall (rm = 3.2 m, φ = 180°). During testing, the model was set up at geometric angle of attack a = 0°, and at heights of 20 cm above the ground surface.
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Instrumentation
The vibration of the model was measured using five Panasonic short rang lasers (HL-G112-A-C5) with a nominal range of 120 mm +/-60 mm; three of them were positioned to measure its vertical movement, and the other two focused to measure the horizontal movement at each of its ends. The upper vertical springs were suspended from the test rig using four load cells, which are rated as 150 N (AEP TS-25kg). These load cells yield axial forces to evaluate the dynamic lift and torque acting on the model. Whereas the lateral force was measured using two horizontal load cells rated as 5 kg (AEP TCA-5kg). The combination of sensors provides insight into the bridge section’s motion in 3 degrees of freedom: mainly the drag (horizontal), lift (vertical) and pitch (torsional) motions. In addition, a single TFI cobra probe was placed upstream of the mid-point of the bridge model at r = 2.7 m, directed towards the centre of the turntable.
2. Downburst Wind Effects
This test involved the bridge section model subjected to Downburst flow of various strengths. The model was positioned 320 cm downwind from the center of the turntable facing the 60-fan wall (rm = 3.2 m, φ = 180°). The model angle of attack was tested at angles a = 0°, and at heights of 20 cm above the ground surface at r/D = 1.0. In addition, the radial position of the impinging jet (rjet) was varied relative to the model to achieve r/D = 0.6, 0.8, 1.2, 1.4, and 1.6, only the downburst strength was varied for these positions, the angle of attack a = 0°.
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Instrumentation
Similar instrumentation was used as described in S4.E1.
3. Combined Downburst and ABL Effects
This test involved the bridge section model subjected to various downburst simulations with an ABL head wind of approximately 4-5m/s, generated from the 60-fan wall. The model was positioned 320 cm radially from the center of the turntable at angles of φ = 180°, and 210°. During the φ = 180° and 210° positions the model was tested with angles of attack of a = 0°, and at a height of 20 cm. The impinging jet was at a position of r/D = 1.0 relative to the model for all tests.
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Instrumentation
Similar instrumentation was used as described in S4.E1. However, at model position φ = 210°, the reference cobra probe followed a similar positional change, while being directed at the centre of the impinging jet the probe was placed at φ = 210°, r = 270 cm, and a height of 20 cm.
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Creative Commons Attribution 4.0 International.
CC BY 4.0
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