Investigation of transmission of pedestrian-induced vibration into a vibration-sensitive experimental facility

Abstract

This paper is based on field measurements that were undertaken in a facility housing ultra-low level vibration sensitive equipment. The aim of these tests was to better understand the vibration transmission from an overhead pedestrian footbridge to a pile supported experimental floor and the supported vibration sensitive equipment. The results of experimental measurements to estimate the as-built modal properties (natural frequencies, modal damping ratios and mode shapes) of the footbridge structure are presented as well as response measurements at selected locations on the footbridge and experimental floor from controlled walking tests. These series of measurements indicate that vibrations are transmitted from the footbridge to the experimental floor as well as to the supported equipment. This is verified through transmissibility checks which also indicate that vibrations from the experimental floor are transmitted onto the supported equipment over the frequency bandwidth considered. The assessment of vibration levels using vibration criteria curves for response measurements on the experimental floor and the supported equipment for ambient (quiet conditions) and controlled walking excitations on the footbridge structure are also provided