PSI - Issue 64

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ScienceDirect Structural Integrity Procedia 00 (2023) 000 – 000 Structural Integrity Procedia 00 (2023) 000 – 000 Available online at www.sciencedirect.com Available online at www.sciencedirect.com ^ĐŝĞŶĐĞ ŝƌĞĐƚ Available online at www.sciencedirect.com ^ĐŝĞŶĐĞ ŝƌĞĐƚ

www.elsevier.com/locate/procedia www.elsevier.com/locate/procedia

Procedia Structural Integrity 64 (2024) 685–692

SMAR 2024 – 7th International Conference on Smart Monitoring, Assessment and Rehabilitation of Civil Structures Operation modal analysis on prestressed concrete beams with shear or flexural cracks Emanuele Gandelli a *, Giulia Rossini a , Matteo Lamberti a , Stefano Giuseppe Mantelli a , Luca Facconi a , Fausto Minelli a a Department of Civil, Environmental, Architectural Engineering and Mathematics (DICATAM), University of Brescia, Italy Abstract This study aimed to apply Operation Modal Analysis (OMA) techniques on prestressed concrete beams (PCBs) in order to identify early warning signs of structural damages, such as changes in natural frequencies and/or relevant mode shapes. The main novelty, compared to past similar investigations, is the employment of OMA to these particular damage-scenarios: (1) a PCB equipped with bonded strands affected by “almost pure” shear -cracks; (2) a PCB equipped with unbonded strands affected by small and reversible flexural-cracks. It was found that, especially in the second case, variations of the natural frequencies may not be an effective index of damage. On the contrary, a qualitative comparison between undamaged and damaged identified mode shapes can be useful for the spatial location of the cracks. Although not among primary objectives, it was also ascertained that OMA techniques are not suitable to assess the actual residual s trands’ tensile load within typical variation ranges during bridges’ service life. © 2024 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of SMAR 2024 Organizers Keywords: prestressed concrete beam; damage detection; shear cracks; operational modal analysis; frequency domain decomposition 1. Introduction Operational Modal Analysis (OMA) algorithms have been developed over the last three decades to perform the dynamic characterization of civil structures when exposed to ambient vibrations only (Brincker and Ventura, 2015). SMAR 2024 – 7th International Conference on Smart Monitoring, Assessment and Rehabilitation of Civil Structures Operation modal analysis on prestressed concrete beams with shear or flexural cracks Emanuele Gandelli a *, Giulia Rossini a , Matteo Lamberti a , Stefano Giuseppe Mantelli a , Luca Facconi a , Fausto Minelli a a Department of Civil, Environmental, Architectural Engineering and Mathematics (DICATAM), University of Brescia, Italy Abstract This study aimed to apply Operation Modal Analysis (OMA) techniques on prestressed concrete beams (PCBs) in order to identify early warning signs of structural damages, such as changes in natural frequencies and/or relevant mode shapes. The main novelty, compared to past similar investigations, is the employment of OMA to these particular damage-scenarios: (1) a PCB equipped with bonded strands affected by “almost pure” shear -cracks; (2) a PCB equipped with unbonded strands affected by small and reversible flexural-cracks. It was found that, especially in the second case, variations of the natural frequencies may not be an effective index of damage. On the contrary, a qualitative comparison between undamaged and damaged identified mode shapes can be useful for the spatial location of the cracks. Although not among primary objectives, it was also ascertained that OMA techniques are not suitable to assess the actual residual s trands’ tensile load within typical variation ranges during bridges’ service life. © 2024 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of SMAR 2024 Organizers Keywords: prestressed concrete beam; damage detection; shear cracks; operational modal analysis; frequency domain decomposition 1. Introduction Operational Modal Analysis (OMA) algorithms have been developed over the last three decades to perform the dynamic characterization of civil structures when exposed to ambient vibrations only (Brincker and Ventura, 2015). © 2024 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of SMAR 2024 Organizers

* Corresponding author. Tel.: +39 0303715968 E-mail address: emanuele.gandelli@unibs.it * Corresponding author. Tel.: +39 0303715968 E-mail address: emanuele.gandelli@unibs.it

2452-3216 © 2024 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of SMAR 2024 Organizers 2452-3216 © 2024 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of SMAR 2024 Organizers

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