Research Centre: Research Centre for Systems & Control
Speaker: Dr Agathoklis Giaralis, Lecturer in Structural Engineering, City, University of London
Vibration-based health monitoring (VHM) techniques are commonly considered for non-destructive condition assessment, design verification, and damage detection in civil engineering structures. They rely on acquiring and processing response acceleration signals from vibrating structures excited by ambient (e.g., wind and traffic induced) dynamic loads under operational conditions. The consideration of wireless sensor networks (WSNs) has been an important development in the past 20 years in facilitating VHM as they allow for less obtrusive, more economical, and rapid deployment compared to wired sensors especially in monitoring large-scale and geometrically complex civil engineering structures. Still, wireless sensors require frequent battery replacement which increases the maintenance cost of VHM while the amount of data that can be reliably transmitted within WSNs is subjected to bandwidth limitations. To this end, different non-uniform in time data acquisition strategies allowing for sampling at average rates significantly below the Nyquist frequency are herein discussed as a means to reduce wireless sensors energy consumption and data transmission payloads in VHM applications. Focus is given on discussing techniques that relax signal sparsity assumptions relying on deterministic non-uniform in time sampling which allows for correlation function or, equivalently, for power spectral density function estimation. In this regard, newly emerged fit-for-purpose VHM techniques using sub-Nyquist sampled structural response acceleration measurements without time-domain signal reconstruction are discussed. Applications for output-only system identification from field measurements of a highway overpass and of an on-shore wind turbine are presented as well as for post-earthquake damage detection in building structures.
Dr Agathoklis Giaralis is Senior Lecturer in Structural Engineering in the Department of Civil Engineering at City, University of London (CUoL) leading the Smart Structures and Structural Health Monitoring Research Unit within the Research Centre for Civil Engineering Structures. He holds a Diploma in Structural Engineering and an MSc in Earthquake Resistant Design of Structures from the Department of Civil Engineering of Aristotle University of Thessaloniki, Greece. He received a PhD in Civil Engineering from Rice University in 2008, partly funded by the Fulbright Exchange Programme, and joined CUoL in 2009. He has published more than 80 papers in peer-reviewed international journals and conference proceedings on nonlinear stochastic dynamics, structural vibration control and health monitoring, and earthquake engineering. He is member of ASCE and a Chartered Engineer in Europe.
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When and where
1.00pm - 2.00pmMonday 18th March 2019