63,472 research outputs found
Vibration-based structural health monitoring: Challenges and opportunities
No full textIn the last twenty years vibration-based methods for Structural Health Monitoring (SHM) have received increasing attention by both academics and operators, due to undoubtable advantages they provide for damage identification purposes. These are mainly related to the capability of providing continuous information about the global state of the structure without a prior knowledge about the location of possible damages and without the need to access the damaged portion of the structure. These methods rely on the fact that a damage inducing a loss of stiffness results in a change of the dynamic behavior therefore, structural responses to forced or ambient vibrations can be used to retrieve information about these changes. Despite the large amount of literature published on these methods, their experimental validation is often limited to highly controlled laboratory conditions or numerical simulations. The validation of the algorithms on real damaged structures is often hampered by the unavailability of data and this constitutes indeed a challenge for the implementation of these techniques at the operational level. In the first part of this paper the possible drawbacks related to the effect of uncertainties related to the effect of environmental sources, noise in hardware systems for the acquisition and transmission of structural responses and approximations in the adopted models. Another aspect that has slow down the practical diffusion of these methods, and generally of SHM techniques, is the difficulty to quantify their benefits prior to their implementation. This has sometime restraint the operators from investing on them, despite the several advantages these systems offer in terms of maintenance optimization and emergency management. In the paper some recent research efforts on several aspects related to the development and implementation of these methods are illustrated
Value of Information Analysis Accounting for Sensor Data Quality: focus on drift
No full textStructural health monitoring plays a crucial role in assessing the condition of civil structures, providing information for regular maintenance and post-disaster emergency management. However, the reliability of structural health monitoring outcomes can be compromised by sensor malfunctions. Over the past two decades, sensor validation tools have been proposed to identify and discard abnormal measurements before extracting information from the structural health monitoring system. The long-term benefits of structural health monitoring systems are commonly evaluated without considering the possibility of faulty sensors. This can lead to suboptimal maintenance decisions. Recently, a Bayesian decision theory-based framework has been introduced to account for different data quality issues and quantify the benefit of implementing a sensor validation tool. This novel approach expands the traditional Value of Information concept to encompass multiple "functioning" states of the structural health monitoring system. This paper mainly focused on a specific data quality issue, i.e., bias or drift in the monitoring outcome. Previous applications of this framework regard simplified decision scenarios, where the monitoring system was either “damaged” or “undamaged”, considering a fixed drift value. In this paper, the impact of uncertain drift levels on the Value of Information in structural health monitoring is investigated, addressing real-world complexities. A numerical case study is considered to illustrate the practical implications of the VoI framework
Synthetic Aperture Radar Interferometry for Structural Health Monitoring of Bridges: Potentialities and Open Research Questions
No full textThe development of synthetic aperture radar (SAR) interferometry has provided unprecedented opportunities to remotely analyze the behavior of civil structures, transcending traditional limitations associated with in-situ methods. However, while the effectiveness of SAR technology in monitoring wide-area geohazards is demonstrated in several applications, its extension to civil structures, which have a much smaller footprint, requires further investigation of several aspects. This paper investigates the potentialities and challenges connected with the use of SAR technology for civil engineering artifacts, fostered by the availability of remote satellite open data. Recently, the European Space Agency has introduced the European Ground Motion Service (EGMS) under the Copernicus program. This innovative and freely accessible resource provides comprehensive information regarding ground motion across Europe through multitemporal interferometric analysis of Sentinel-1 images acquired since 2015. In this paper the focus is on the Palatino Bridge in Rome, Italy. Data from the ascending and descending orbit are combined to obtain vertical and longitudinal displacements of the structure, allowing for a better estimation of the bridge's response to varying environmental conditions. Results are then compared with those obtained processing high resolution data from COSMO-SkyMed of the Italian Space Agency, showing the consistency of findings
On the standardization of procedures for Structural Health Monitoring
No full textThe aim of this paper is to outline the different aspects of the Structural Health Monitoring process that should be standardized in order to provide the stakeholders with consensual procedures for their implementation and use on the lifecycle, thereby improving the diffusion of such systems at a large scale on structures and infrastructures
Value of Information analysis accounting for data quality
No full textStructural Health Monitoring (SHM) can provide valuable information for maintenance-related activities and post-disaster emergency management. However, as with any technological system, SHM systems can be susceptible to errors due to malfunctioning. Therefore, it is essential to assess the potential for malfunctions and the associated costs of maintenance and repair when evaluating the long-term benefits of SHM systems. In the last two decades, sensor validation tools (SVTs) have been proposed to support decisions by isolating and discarding abnormal data. Recently, the authors of this paper have proposed a framework based on the Value of Information (VoI) from Bayesian decision analysis to account for different states of an SHM system and assess the benefit of SVT information. By quantifying the additional value obtained from SVTs, decision-makers can make more informed decisions about investing in these systems. This framework is here demonstrated on a real case study, namely the S101 bridge in Austria, which has been artificially damaged for research purposes. The benefit of collecting SHM and SVT information is quantified by considering a simple decision problem related to the management of the bridge in the aftermath of a damaging event. Overall, the study highlights the potential benefits of using SVTs to improve the reliability of SHM data and inform decision-making in the management of structures
Value of Seismic Structural Health Monitoring Information for Management of Civil Structures Under Different Prior Knowledge Scenarios
No full textSeismic Structural Health Monitoring (S2HM) provides information about the integrity of civil structures and infrastructure in the aftermath of an earthquake. However, quantifying the benefits of S2HM information is crucial to justify the investment in S2HM systems. The benefit of S2HM can be computed through the Value of Information (VoI) from Bayesian decision theory, which compares the expected costs of alternative actions with prior information (without S2HM information) and with S2HM information (before it is available). This paper aims to analyze the VoI from S2HM in civil structures and infrastructure, considering different prior information scenarios regarding seismic action. The theoretical framework of the VoI is adapted to address three prior knowledge scenarios: (i) full information about the earthquake is available (ii) the intensity measure of the seismic motion is obtained using ground motion models, and (iii) no information is available. A numerical case study of a structure in a seismic area is presented, and the effect of different prior information scenarios on the VoI is discussed. The results show that VoI is higher when the prior information is low, indicating that monitoring systems are more valuable when uncertainty about seismic actions is high
Experimental verification of the interpolation method on a real damaged bridge
No full textThe identification of damage in a bridge from changes in its vibrational behavior is an
inverse problem of important practical value. Significant advances have been obtained on this
topic in the last two-three decades, both from the theoretical and applied point of view. One of
the main problems when dealing with the assessment of vibration based damage identification
methods is the lack of experimental data recorded on real damaged structures. Due to this, a large
number of damage identification algorithms are tested using data simulated by numerical
models. The availability of data recorded on a damaged bridge before its demolition gave the
authors the uncommon chance to verify the sensitivity and reliability of the IDDM basing on
data recorded on a real structure. Specifically data recorded on a reinforced concrete single-span
supported bridge in the Municipality of Dogna (Friuli, Italy) were used to apply the damage
localization algorithm. Harmonically forced tests were conducted after imposing artificial,
increasing levels of localized damage. In this paper the sensitivity of the method is discussed
with respect to the number of instrumented locations and to the severity of the damage scenarios
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Value of vibration-based structural monitoring for bridge emergency management
No full textContinuous monitoring of the structural response to vibrations enables to acquire real-time information that can support asset management decisions. Despite the several advantages provided by the availability of continuously updated information, the adoption of vibration-based monitoring systems still encounters difficulties to be implemented at large scale due to their perceived high cost and the difficulty to estimate the return on investment before their implementation. The Value of Information (VoI) analysis from Bayesian decision theory can be used to quantify the benefits associated with vibration-based monitoring information in supporting the selection of optimal asset management actions. In this paper, a framework to quantify the VoI from vibration-based monitoring is outlined, the principal ‘ingredients’ needed for its implementation are described, and examples of its application for emergency managements are used to illustrate the general framework
Comparison of indicators of damage location based on information gain
No full textVibration-based methods for damage localizations are often based on a damage feature defined in terms of changes of modal or operational shapes. These methods allow detecting variations of the damage feature that can be attributed to damage. Many of these methods are based on the detection of irregularities in the modal shapes of the structure. In this paper, the performance of several algorithms for damage localization is investigated and the results are compared both qualitatively, in terms of the capability to correctly localize damage, and quantitatively, in terms of relative information entropy. This parameter quantifies the gain of information obtained a given damage indicators with respect to a reference one. As reference damage indicator is assumed the prior probability of damage defined in terms of expert opinion or as a non-informative parameter. The investigation is carried out using responses simulated using the calibrated finite element model of a real Italian bridge permanently monitored by the Italian Seismic Observatory of Structures
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