Reynolds, Paul (2000) The effects of raised access flooring on the vibrational performance of long-span concrete floors. PhD thesis, University of Sheffield.
Abstract
There is a current trend towards ever more slender concrete floor structures, which is
resulting in more frequent problems with their vibration serviceability. Predictive
methods for vibration serviceability must consider not only the structures themselves,
but also the non-structural elements which are attached to them, as these may have a
significant effect on the dynamic characteristics of the floor structural system. As there
has been very little past research in this area, this thesis describes an investigation into
the effects of raised access floors on the vibration serviceability of long-span concrete
floors.
The development of a new modal testing facility based on electrodynamic shaker
excitation, which was capable of producing high quality estimates of the modal
properties of full-scale floor structures, is described. This was subsequently utilised to
determine the modal properties of three full-scale floor structures, before and after the
installation of various configurations of raised access floors. The response of these
structures to controlled pedestrian excitation was also measured. Realistic finite element
models of all structures were developed and updated using the results from the
experimental work. These were subsequently utilised for investigation of the
experimentally measured effects of the raised access floors.
It was found that raised access floors had only minor effects on the modal properties of
the long-span concrete floors. Reductions in natural frequencies due to the increased
mass were, to some extent, offset by the slight increases in stiffness following the
installation of the access floors. Modal damping ratios increased for some modes of
vibration, but these changes were rather unpredictable and hence they were too
unreliable to be used in design.
The response of the structures under controlled pedestrian excitation reduced following
the installation of various configurations of raised access floors. The reduction appeared
to be greater for relatively deep access floors (500 - 600 mm) than for relatively shallow
access floors (150 - 200 mm). Therefore, it is recommended that the effects of access
floors may be included in vibration serviceability analyses by applying a reduction
factor to predicted responses calculated by assuming a bare floor. The proposed
reduction factors are 0.9 for access floors where the finished floor height is less than
500 mm and 0.8 for access floors where the finished floor height is 500 mm or greater.
Metadata
Keywords: | Structural engineering |
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Awarding institution: | University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Engineering (Sheffield) > Civil and Structural Engineering (Sheffield) |
Identification Number/EthosID: | uk.bl.ethos.322934 |
Depositing User: | EThOS Import Sheffield |
Date Deposited: | 18 Jan 2017 12:37 |
Last Modified: | 18 Jan 2017 12:37 |
Open Archives Initiative ID (OAI ID): | oai:etheses.whiterose.ac.uk:15044 |
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