Title

ACROSS-WIND RESPONSE OF SLENDER STRUCTURES OF CIRCULAR CROSS-SECTION TO ATMOSPHERIC TURBULENCE.

Date of Award

1983

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Abstract

A mathematical model which yields estimates of across-wind response is presented. Fluctuating forces from three sources are identified and modeled. They are forces due to vortex shedding, forces induced by the lateral component of turbulence and forces induced by motion. The motion dependent force, which in reality is a complex flow-structure interaction phenomenon, is incorporated in the model through a simple device. The model is semi-empirical in construction, and relies on the results from laboratory-scale experiments for the empirical component.;The reliability of the predictions depends not only on the fidelity of the mathematical model but also on the quality of input data. The input data are considered in three categories, and they are the wind field, the aerodynamic coefficients and the structural parameters.;Recent models of the wind developed for engineering purposes are examined in the light of recent measurements of the wind. Theoretically based approaches for characterizing the atmospheric boundary layer are reviewed.;The aerodynamic coefficients which determine the fluctuating loads on the structure are examined thoroughly. The inability of laboratory-scale experiments to simulate certain flow parameters, typical of full-scale situations, is discussed. An attempt is made to reconcile laboratory-scale and full-scale measurements of the aerodynamic coefficients with a view to providing guidance for selecting appropriate values for response prediction purposes.;The measurements, of a variety of parameters, in a full-scale experiment on the dynamic response of a 130 m reinforced concrete chimney are analyzed. Results from the analysis provide a unique opportunity for examining the performance of the mathematical model. Comparison of the predicted response and measured response was generally satisfactory.;Further case studies, smaller in scope than the experiment mentioned above, of full-scale response are investigated. Again, the response was computed using the mathematical model and compared with the measurements. In view of the uncertainties, the comparisons are encouraging.

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