Full-scale investigation of the effects of wind turbulence characteristics on dynamic behavior of long-span cablesupported bridges in complex terrain
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The global demand for long-span cable-supported bridges are emerging. Impressive number of projects have been realized in the last two decades and many more projects are in their planning, design or construction phases today. Recently, the Norwegian Public Roads Administration took the initiative and started a project to replace ferries along Norway’s coastal E39 highway by fixed links. This requires crossing of wide and deep straits by bridges in the wind-prone Norwegian fjords, where the terrain is mountainous and complex. Some of the straits extend up to 3-5 kilometers, which demand novel bridge designs. Accomplishment of such bridge projects is only possible with a deep understanding of the wind environment, terrain-induced effects, wind-structure interaction and the uncertainties involved in analytical methodologies. In this context, Hardanger Bridge, currently the longest suspension bridge in Norway (main span 1308 meters), has been instrumented to investigate characteristics of the turbulent wind environment and the dynamic response of the bridge. In this thesis, large amount of data collected from the Hardanger Bridge monitoring system over a period of almost four years are analyzed to study the wind characteristics and dynamic response of the bridge. Response surface analyses is employed to examine the wind-response relationship from a statistical point-of-view. Analytical predictions of the dynamic response are carried out using multimode buffeting theory and compared with the measurements. The measurement data are then used to deduce a probabilistic turbulence model that can be used in long-term extreme response estimation and reliability based and probabilistic analyses. The investigations surfaced that the wind-induced response of the Hardanger Bridge showed significant variability, implying significant amount of uncertainty inherently present in the dynamic response analyses. To a large extent, this is found to root from the variable wind turbulence field. Therefore. It is stressed that this variability might cause unfavorable designs and should be handled rationally. In light of these findings and using field measurements, a probabilistic turbulence model is devised and its ability to represent the measured turbulence field is shown. Prediction of the wind-induced dynamic response of a cable-supported bridge is a complex problem, involving characterization of the turbulence field, determination of structural, dynamic and aerodynamic properties of the structure and modeling of the fluid-structure interaction. Consequently, analytical treatment of such a problem involves a great deal of modeling and parametric uncertainties, and requires validation by full-scale measurements. Comparison of the analytical predictions with fullscale measurements remains as the most reliable approach for evaluation of performance of the available analytical tools. The comparisons throughout the thesis indicates discrepancies between measurements and analytical results, where the sources of which are difficult to identify. Further research is needed that will aid in calibration or improvement of the available tools.
Består avPaper 1: Fenerci, Aksel; Øiseth, Ole; Rønnquist, Anders. Long-term monitoring of wind field characteristics and dynamic response of a long-span suspension bridge in complex terrain. Engineering structures 2017 ;Volum 147. s. 269-284
Paper 2: Fenerci, Aksel; Øiseth, Ole. Measured Buffeting Response of a Long-Span Suspension Bridge Compared with Numerical Predictions Based on Design Wind Spectra. Journal of Structural Engineering 2017 ;Volum 143.(9) s. – Not included due to copyright restrictions. Available at: http://dx.doi.org/10.1061/(ASCE)ST.1943-541X.0001873
Paper 3: Fenerci, Aksel; Øiseth, Ole. Evaluation of wind-induced response predictions of a long-span suspension bridge using full-scale measurements. 7th European African Conference of Wind Engineering; 2017-07-03 - 2017-07-07. Not included due to copyright restrictions.
Paper 4: Fenerci, Aksel; Øiseth, Ole. Strong wind characteristics and dynamic response of a long-span suspension 1 bridge during a storm. Journal of Wind Engineering and Industrial Aerodynamics 2018 ;Volum 172. s. 116-138.
Paper 5: Fenerci, Aksel; Øiseth, Ole. Site-specific data-driven probabilistic wind field modeling for the wind-induced response prediction of cable-supported bridges. Journal of Wind Engineering and Industrial Aerodynamics 2018 ;Volum 181. s. 161-179. © 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/