University of Stavangeruis.no

Jasna Bogunović Jakobsen

http://nn.wikipedia.org/wiki/Uburen#mediaviewer/File:Lysefjordbroen_sett_fra_Sokkanuten.jpg

PhDs / research work in connection with the Coastal Highway Route E39

at the University of Stavanger

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Overall research goal

Improve understanding and modelling of wind loads and wind-induced response of long-span bridges, in order to facilitate an economic and safe bridge design.

Collaboration with the NPRA: Support by NPRA for two research positions closely related to the ongoing PhDs:

A) Ambient load and vibration data acquisition and interpretation B) Wind-induced cable vibrations

Support and collaboration on the full-scale measurement campaigns Partial support to ongoing PhDs Adjunct Professor in Wind Engineering: Jonas Snæbjornsson

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Ongoing PhDs

Heidi Christensen

Aerodynamics of bridge cables

PhD student since 2012.

Etienne CheynetBridge vibrations due to turbulence

PhD student since 2013.

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B Stay cable vibrations 1

Focus on vibrations caused by rapidly changing/ unstable flowstates in the so-called drag crises.

Pressure distributions, fixed model, Re=1.1∙105 (left), Re=3.2∙105 (middle), Re=5.8∙105 (right)

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B Stay cable vibrations 2

Study of the effect of hellical fillets on cableaerodynamics.

Study of the effect of turbulence on cableaerodynamics.

Influence of cable non-circularity on theaerodynamics.

Research collaboration with the National Research Council Canada, University of Bristol, the US Federal Highway Administrataion and the Danish Technical University.

Other topics: vibrations of cables/hangers (ice-wind,…), vibration mitigation measures …

(Model) cable-cross section, deviation from the circularshape magnified

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A Bridge response due to turbulence

Measurement of wind conditions in complex terrain and theassocaited bridge vibrations.

Investigation of the link between the two, ref. the so-calledbuffeting theory.

Efficient techniques for the interpretation of the measuredresponse data, including wind-structure interaction, and thestructural health monitoring.

Remote wind velocity sensing in bridge engineering.

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University of Stavanger University of Bergen Christian Michelsen Research ASTechnical University of Denmark

http://nn.wikipedia.org/wiki/Uburen#mediaviewer/File:Lysefjordbroen_sett_fra_Sokkanuten.jpg

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Lidar measurement principlesLight Detection and Ranging

Doppler shift:

Lidar recording principles:

Wind flow characterization by a long-range pulsed Doppler lidar (March 2014 – June 2014)

Collaboration between UiS and NORCOWE (UiB, CMR and Leosphere)

WindCube100S, scanning modes: Doppler Beam Swinging mode (DBS) Plan Position Indicator mode (PPI) Range Height Indicator mode (RHI) Sequential Fixed Line of Sight mode (LOS)

Azimuth 13° to 63°

PPI, elev. 0.8°, 1.8° and 3.2° RHI Azimuth 37 °,38 ° and 39 °

Wind characteristics observed by lidars in a “dynamic” scanning modeExample of a Plan Position Indicator mode (PPI) data by WindCube100S

22.5.2014, 18:19:23 elev=3.2° 22.5.2014, 18:19:10 elev= 1.8°

Non-scanning, fixed line-of-sight, measurements:Example of a LOS data by WindCube100S,

Radial wind velocity recorded by a LOS scan elev=1.8°azim=39°; 22.05.2014 starting at 16:12:06 11

Multi-lidar measurements, May 2014Short range WindScanners deployment

Two short-range WindScanners developed by the Technical University of Denmark, building on ZephIR150, deployed on the bridge walkway on the West side.

Synchronized to map the airflow in different planes (horizontal and “vertical”) SW from the bridge, and operated remotely.

High-frequency, separate LOS data also recorded. The Doppler spectra averaged such that LOS wind

velocities were provided at about 390 Hz and the scan pattern frequency was 1 Hz.

Scanning sequences devoted to capturing the spatial characteristics of the inflow, as well as various forms of the bridge signature in the airflow.

Horizontal wind speed along the bridge axis measured by the WindScanners and the sonic anemometer

22.5.2014 starting from 16:13:24

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Spectra based on short-range WindScanners and sonic anemometers

Power spectral density of the longitudinal (left) and lateral turbulence (right),based on 20 minutes data starting at 17:20, 22.5.2014.

k1=2π∙f /U

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Coherence based on short range WindScanners and sonic anemometers

Squared coherence of the along-wind turbulence (left) and the lateral turbulence (right).D is the across-wind projection of the distance Δy between the observation “points”.

)()()(

),(11

212

1 kFkFkF

kDCohuBuA

uAuBu =

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Summary

Coastal Highway Route E39 Project connects well to theongoing work and triggers further reserach in wind engineeringat UiS.

Many more topics to be explored (aerodynamics of multi-boxbridge girders, etc…)

New staff at UiS in marine technology, CFD….

Research network facilitates novel applications.

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