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On the standardization of procedures for Structural Health Monitoring
Full text linkThe 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
Vibration-based structural health monitoring: Challenges and opportunities
Full text linkIn 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
Experimental verification of the interpolation method on a real damaged bridge
Full text linkThe 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
The value of seismic structural health monitoring for road bridges
No full textIn the aftermath of seismic events, the availability of real time Structural Health Monitoring (SHM) information can support the selection of the most efficient emergency management plan. A remaining issue in SHM is to convince owners and operators of infrastructure of what is the “added-value” of SHM and what are its social and economic benefits. The Value of Information (VoI) from Bayesian decision theory has been recently proposed to this aim. In this paper, the general methodology to compute VoI from Seismic SHM (S2HM) is described and a sensitivity analysis is carried out to investigate in which cases the installation of a S2HM provides the higher benefit. Specifically, the sensitivity analysis is carried out considering a range of different structural properties of the bridge and different seismic hazard levels. Results demonstrate that, for the considered decision scenario, the installation of a S2HM system is particularly convenient for relatively weak bridges located in high seismicity areas
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