Findings with AVC Design for Mitigation of Human Induced Vibrations in Office Floors

Abstract

In recent years, there have been extensive active vibration control (AVC) studies for the mitigation of human induced vibrations in a series of office floors, in which such vibrations are deemed to be ‘problematic’ and have been found to affect only certain sections of the floors. These floors are predominantly open-plan in layout and comprise of different structural configurations for their respective bays and this influences their dynamic characteristics. Most of the AVC studies have comprised extensive analytical predictions and experimental implementations of different controller schemes. The primary measures of vibration mitigation performance have been by frequency response function (FRF) measurements, responses to controlled walking tests, and in-service monitoring, all tests with and without AVC.

This paper looks at AVC studies in three different office floor case studies in past field trials. Some of the estimated modal properties for each of these floors from experimental modal analysis (EMA) tests are shown as well as some selected mode shapes of fundamental modes of vibration. These reflect the variability in their dynamic characteristics by virtue of their different designs and thus the potential for their ‘liveliness’ under human induced excitation. An overview of some of the controller schemes pursued in the various field trials are mentioned as well as a brief insight being provided into some challenges encountered in their designs and the physical siting of the collocated sensor and actuator pairs used in the field trials. The measure for the vibration mitigation performances in this work is in the form of uncontrolled and controlled point accelerance FRFs which show attenuations in the target modes of vibration between 13 and 18 dB. These tests also show the variability in vibration mitigation performances between the various controllers.