Álvaro Cunha

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elsa caetano

Universidade do Porto

Michele Brun

University of Cagliari

Franco Bontempi

Università degli Studi "La Sapienza" di Roma

Mikail F Lumentut

National Taiwan University

Dionysius Siringoringo

Yokohama National University

Harijono Djojodihardjo

Institut Teknologi Bandung

Chandramouli Padmanabhan

IIT Madras

Dario Pastrone

Politecnico di Torino

Jana Javornik

University of East London

Gwen Robbins Schug

University of North Carolina at Greensboro

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Papers by Álvaro Cunha

Vibration-based damage detection in wind turbine blades using Phase-based Motion Estimation and motion magnification

Journal of Sound and Vibration, 2018

Vibration-based Structural Health Monitoring (SHM) techniques are among the most common approache... more Vibration-based Structural Health Monitoring (SHM) techniques are among the most common approaches for structural damage identification. The presence of damage in structures may be identified by monitoring the changes in dynamic behavior subject to external loading, and is typically performed by using experimental modal analysis (EMA) or operational modal analysis (OMA). These tools for SHM normally require a limited number of physically attached transducers (e.g. accelerometers) in order to record the response of the structure for further analysis. Signal conditioners, wires, wireless receivers and a data acquisition system (DAQ) are also typical components of traditional sensing systems used in vibration-based SHM. However, instrumentation of lightweight structures with contact sensors such as accelerometers may induce mass-loading effects, and for large-scale structures, the instrumentation is labor intensive and time consuming. Achieving high spatial measurement resolution for a large-scale structure is not always feasible while working with traditional contact sensors, and there is also the potential for a lack of reliability associated with fixed contact sensors in outliving the lifespan of the host structure. Among the state-of-the-art noncontact measurements, digital video cameras are able to rapidly collect high-density spatial information from structures remotely. In this paper, the subtle motions from recorded video (i.e. a sequence of images) are extracted by means of Phase-based Motion Estimation (PME) and the extracted information is used to conduct damage identification on a 2.3-meter long Skystream® wind turbine blade (WTB). The PME and phased-based motion magnification approach estimates the structural motion from the captured sequence of images for both a baseline and damaged test cases on a wind turbine blade. Operational deflection shapes of the test articles are also quantified and compared for the baseline and damaged states. In addition, having proper lighting while working with high-speed cameras can be an issue, therefore image enhancement and contrast manipulation has also been performed to enhance the raw images. Ultimately, the extracted resonant frequencies and operational deflection shapes are used to detect the presence of damage, demonstrating the feasibility of implementing non-contact video measurements to perform realistic structural damage detection.

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Dynamic monitoring of wind turbines: case studies onand off-shore

CRC Press eBooks, Sep 7, 2015

Validation of an Automated Approach for the Definition of Reference Modal Properties on Onshore Wind Turbines

Lecture notes in civil engineering, 2023

Identificação modal estocástica de estruturas de engenharia civil

Centre Internacional de Mètodes Numèrics en Enginyeria (CIMNE) eBooks, 2005

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Vibration Monitoring of Construction Work and Industrial Activities Using New Solutions of Instrumentation

EURODYN ..., 2020

Dynamic Tests and Continuous Monitoring of a Moveable Cable-Stayed Bridge

<u>Footbridge 2008 - Footbridges for Urban Renewal</u>, Third International Conference on Footbridges, 2-4 July 2008, Porto, Portugal, 2008

Summary A new cable-stayed footbridge was constructed over the entrance to the yachting marina of... more

Ambient re-testing of the Humber Suspension Bridge

Cable-deck dynamic interactions at the International Guadiana Bridge

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Dynamic testing of the Millau Viaduct

Implementation of a control system in a lively footbridge

Output-only modal identification of Luiz I Bridge before and after rehabilitation

Implementation of a dynamic monitoring system at Trezói railway bridge

Coimbra footbridge is a new structure that connects both banks of Mondego River. Preliminary stud... more Coimbra footbridge is a new structure that connects both banks of Mondego River. Preliminary studies conducted during design stage indicated some vulnerability to vibrations induced by pedestrians, both for lateral and vertical directions. As result, it was decided to install Tuned Mass Dampers in 5 different sections of the deck, as well as a dynamic monitoring system to evaluate the vibration levels observed in the footbridge during a period of one year after construction. This paper describes the architecture of the monitoring system, the type of results permanently displayed in a web site specially developed for this application, and some additional software created with the purpose of analysing and reporting the information collected along periods of several months.

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Analysis of the influence of environmental factors on modal properties of the Braga Stadium suspension roof

New solutions of sensors and instrumentation for dynamic monitoring of Civil structures: ViBest/FEUP experience

Contribution to new solutions of instrumentation of Civil structures for continuous dynamic monitoring

High spatial resolution operational modal analysis of a football stadium suspension roof

Evaluation of dynamic properties of the Infante Dom Henrique Bridge

Experimental characterization of the dynamic behaviour of lively footbridges

... Álvaro CUNHA Associate Aggregate Professor Faculty of Engineering of University of Porto Port... more

Dynamic Monitoring of a Cable-Stayed Bridge: Monitoring System and First Results

Lecture notes in civil engineering, Jun 16, 2022

The Éric Tabarly bridge in Nantes is a 210m long cable-stayed road bridge crossing the Loire Rive... more The Éric Tabarly bridge in Nantes is a 210m long cable-stayed road bridge crossing the Loire River, that was inaugurated in 2011. It is composed of a 27 m wide steel deck divided into two spans by a 57 m high steel pylon, being the main span 143m long. In the context of the European Research Project DESDEMONA (DEtection of Steel DEfects by Enhanced MONitoring and Automated procedure for self-inspection and maintenance), the bridge has been equipped with a dynamic monitoring system, constituted of 16 uniaxial accelerometers installed both on the deck and on the Pylon, with accelerations being recorded with a sampling rate of 100 Hz. This paper describes the dynamic monitoring system installed in the bridge and the results achieved during the first months of operation, including the characterization of vibration levels (maximum and effective values) as well as the automatic identification of the bridge modal properties. Finally, the effects of operational and environmental conditions on modal properties are studied.

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Tree Top Walk at Serralves Park, Portugal

Footbridge 2022, Madrid: Creating Experience, 2021

The current paper describes the structure and the dynamic behaviour of a footbridge built in Serr... more The current paper describes the structure and the dynamic behaviour of a footbridge built in Serralves Park at Porto, Portugal. The footbridge, named Tree Top Walk, is located in a slope in the park at the height of the top of the trees. Because it is in a slope, the footbridge develops with an irregular U-shape at a constant level. The total length of the footbridge is approximately 250 m. At its highest level, the height is 15 m.Approximately at one third of the course there is a passage between the two branches of the U. At this zone, there is a staircase that allows to reach the footbridge at the middle of its course, from the woods and a small amphitheatre at a level of 14 m. The structure of the deck is made with timber while the columns are made with steel covered with timber across their height and the connection between the columns and the deck is performed with timber struts placed in the longitudinal and transversal directions. Three of the columns are made with a circula...

Vibration-based damage detection in wind turbine blades using Phase-based Motion Estimation and motion magnification

Journal of Sound and Vibration, 2018

Download

Dynamic monitoring of wind turbines: case studies onand off-shore

CRC Press eBooks, Sep 7, 2015

Validation of an Automated Approach for the Definition of Reference Modal Properties on Onshore Wind Turbines

Lecture notes in civil engineering, 2023

Identificação modal estocástica de estruturas de engenharia civil

Centre Internacional de Mètodes Numèrics en Enginyeria (CIMNE) eBooks, 2005

Download

Vibration Monitoring of Construction Work and Industrial Activities Using New Solutions of Instrumentation

EURODYN ..., 2020