City Research Online

Abstract

The research described in this thesis showed that, under certain conditions, coupling can take place between the lateral and in-line motion of a structure vibrating in a turbulent wind, This has important consequences both for full-scale and for model-scale tests.

Previous researchers have usually confined their investigations to models with only one degree of freedom (lateral), assuming that the in-line motion is of no consequence to the final results. It has been shown here, however, that this assumption can lead to erroneous results, It was found that for a lightly damped structure there is a significant transfer of energy between the two motions of oscillations. With the motion restricted to only one degree of freedom, no such energy transfer takes. place. Consequently, compared to a two degrees of freedom model, a much lower value for the structural damping for the model is obtained,

The above conclusion was reached as a result of tests made on models placed in a generated atmospheric boundary layer (GA8L). The models were mounted on a novel gimbal system, designed and constructed to permit motion with either one or two degrees of freedom, Emphasis was placed on digital techniques as opposed to analogue, for analysing the vibrations of the models and the turbulence structure of the GABL. For this purpose, a digital and an analogue computer were used together for off-line analyses of the various signals,

Publication Type:	Thesis (Doctoral)
Subjects:	Q Science > QC Physics T Technology > TA Engineering (General). Civil engineering (General) T Technology > TG Bridge engineering T Technology > TH Building construction
Departments:	School of Science & Technology > Department of Engineering School of Science & Technology > School of Science & Technology Doctoral Theses Doctoral Theses

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