Structural health monitoring (SHM) and Nondestructive testing (NDT) of slender masonry structures: A practical review

The scientific community is hardly working to propose reliable methodologies of analysis and non-invasive technologies of investigation to assess the current state of conservation of historic buildings to verify their ability to resist future threats. These structures, mostly made of masonry, are difficult to assess due to the heterogeneity of materials and their mechanical behavior, but it is vital to preserve this invaluable cultural heritage by suitable structural assessment techniques. A great deal of research atten-tion has been paid to monitoring their structural health; in many recent publications new advanced tech-nological methods have been provided such as cheaper sensors, wireless connections, non-contact surveys and continuous monitoring. A bibliometric study has shown that more than half of the papers on Structural Health Monitoring (SHM) and Nondestructive Testing (NDT) on masonry have been pub-lished between 2018 and 2020, and 30% of those published in 2020 were on 'slender' elements like tow-ers, chimneys or minarets. This paper presents a wide-ranging review of static and dynamic studies published on SHM and NDT of slender masonry structures summarizing and discussing the different experimental techniques used. With respect to the dynamic testing, Operational Modal Analysis (OMA) by accelerometers is the mostly frequent used technique by scholars, but other promising methods such as radar interferometry are also reported. This overall discussion is concluded with a short review of some examples on numerical structural health assessment and signal processing tools. An inclusive list of papers is provided describing the most important slender masonry structures characteristics, natural frequencies, experimental and numerical techniques employed and reference values. This paper, set on a practical perspective, is expected to be of interest to those researchers and practitioners who require an extensive and up-to-date review of this topic. (c) 2021 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

The scientific community is actively working on proposing reliable analysis methodologies and non-invasive investigation technologies to assess the current state of conservation of historic buildings and to confirm their ability to resist future threats. The focus is on preserving invaluable cultural heritage through suitable structural assessment techniques, with attention paid to monitoring structural health using advanced technological methods like sensors, wireless connections, and continuous monitoring. Research has shown an increase in papers published on Structural Health Monitoring (SHM) and Nondestructive Testing (NDT) of masonry structures, particularly on slender elements in recent years.