Modal identification of damaged frames

Diaferio, Mariella; Sepe, Vincenzo

doi:10.1002/stc.1762

Cited by 10 publications

(9 citation statements)

References 36 publications

(66 reference statements)

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“…As shown in other papers of the writers', such procedure can also be extended to multispan and multi-floor framed structures, where only higher-order modes are significantly affected by local damage, by means of a substructure approach (Bellizzotti 2009;Diaferio and Sepe 2016). In , the possibility of applying such a procedure when the damaged span of a multispan beam is not directly accessible is also discussed.…”

Section: Discussionmentioning

confidence: 94%

Modal identification of localised damage in beams and trusses: experimental and numerical results

Diaferio

Sepe

Bellizzotti³

2019

Int J Adv Struct Eng

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The paper discusses the possibility of detecting local damages in complex structures typical of civil engineering, as multispan beams and trusses. Namely, it describes a procedure to identify localised cracks in structures in the elastic range of behaviour using only the values of natural frequencies in the intact configuration and in the damaged one evaluated by means of dynamic tests. The error minimisation procedure described in the paper selects the solution within a set of finite element models that simulate a range of positions and levels of damage, by identifying the damaged configuration as the one whose modal frequencies minimise the least-square difference with the measured data. The accuracy of the method is first investigated by applying it to the damage detection of a two-span steel beam, whose modal frequencies were obtained by means of experimental tests. To explore the accuracy of the proposed procedure, numerically simulated data with random noise were also generated for several positions and levels of damage and for different values of the random noise. The procedure was then extended, by means of numerical simulations, to the case of a beam with two localised damages. Finally, the procedure proposed for multispan beams is adapted to the damage identification of plane truss structures.

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Section: Discussionmentioning

confidence: 94%

Modal identification of localised damage in beams and trusses: experimental and numerical results

Diaferio

Sepe

Bellizzotti³

2019

Int J Adv Struct Eng

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“…Further insights for the direct problem are in Figures 9 and 10, which show exact solutions (ESs) versus the firstand second-order solutions provided by the PA, both for the eigenvalues (i.e., the imaginary and real parts of eigenvalues of the dynamic problem) and the four components (with real and imaginary parts) of the fastest natural mode (i.e., the fourth mode shape of the dynamic problem) before Liu's rotation. The ESs are so defined since they are the eigensolutions of the complete problem expressed by Equation 9, while the first-and second-order solutions are provided by Equation (21). The curves providing the so-called ESs are solid, the others are dashed.…”

Section: Sensitivity Analysis Of Eigensolutionsmentioning

confidence: 99%

“…Structural health monitoring is suitable in many engineering fields: we may quote Loh et al 18 for vibration-based damage detection in such industrial apparatus as wind turbines; Rainieri and Fabbrocino 19 for monitoring of civil structures and infrastructures in earthquake-prone areas; Oregui et al 20 for monitoring welded bolts by acceleration measurements; Diaferio and Sepe 21 and Antonacci et al 22 on vibration measurements for damage detection in framed structures; and a very recent insight onto possible medical applications is in Ong et al 23 Undamaged civil, industrial or aerospace framed structures can be described as proportionally damped systems, see the well-known monographs: 24,25 the physical quantity describing dissipation (damping) is supposed to be linearly related to the inertial and elastic properties. Then, the structure has real natural mode shapes in linear dynamics and, if it is naturally discrete, or made discrete by suitable assumptions, the mode shapes are lists of real quantities.…”

Section: Introductionmentioning

confidence: 99%

“…Structural health monitoring is suitable in many engineering fields: we may quote Loh et al 18 for vibration‐based damage detection in such industrial apparatus as wind turbines; Rainieri and Fabbrocino 19 for monitoring of civil structures and infrastructures in earthquake‐prone areas; Oregui et al 20 for monitoring welded bolts by acceleration measurements; Diaferio and Sepe 21 and Antonacci et al 22 on vibration measurements for damage detection in framed structures; and a very recent insight onto possible medical applications is in Ong et al 23 …”

Section: Introductionmentioning

confidence: 99%

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Dynamic damage identification using complex mode shapes

Lofrano

Paolone

Ruta

2020

Struct Control Health Monit

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Damage, be it a material or a geometric degradation, modifies some features of the response foreseen by the original structural design. These variations, once the dependence on the damage causing them is established, can be used for identification purposes. In the literature, vibration-based approaches usually compare some responses of linear elastic structures with dissipative properties that are assumed proportional to the mass and stiffness measures. However, such an assumption is reasonable for new, undamaged structures, but can be unreliable in existing, potentially damaged structures, particularly for damages localised in narrow areas. The eigenmodes of a proportionally damped system can be reduced to the real ones of the relevant ideal undamped system. On the other hand, non-proportional damping exhibits complex eigenmodes that cannot be reduced to those of the ideal, or of the proportionally damped, structure. Thus, we may assume the complexity of the eigenmodes as a measure of nonproportional damping, hence of damage. On this basis, some contributions in the literature verified the relationship among presence of damage and amount of complexity. Here, we propose a perturbation approach and an objective function able to identify presence, location and amplitude of localised damages, intended as sources of non-proportionality in viscously damped linear systems. A prototype naturally discrete structure with four degrees-of-freedom is chosen to test and show capability and accuracy of the proposed method.

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“…The identification of structural dynamic properties at seismic input pursues various goals, as response prediction, condition assessment, Structural Control and Health Monitoring, or damage identification. [1][2][3][4][5][6][7][8][9][10][11] Nearly all of the available attempts towards these ends pertain to the realm of Experimental Modal Analysis (EMA), [12][13][14][15][16][17][18] since they need the knowledge or measurement of the input ground motion. However, in most practical cases, the true foundation input motion turns out to be unavailable or unreliable (e.g., not recorded, recorded with low signal-to-noise ratio, or affected by soil-structure interaction (SSI) effects [19] ).…”

Section: Introductionmentioning

confidence: 99%

Seismic FDD modal identification and monitoring of building properties from real strong-motion structural response signals

Pioldi

Ferrari

Rizzi

2017

Struct Control Health Monit

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Summary In the present study, output‐only modal dynamic identification and monitoring of building properties is attempted successfully by processing real earthquake‐induced structural response signals. This is achieved through an enhanced version of a recently‐developed refined Frequency Domain Decomposition (rFDD) approach, which in the earlier implementation was adopted to analyse synthetic seismic response signals only. Despite that short duration, nonstationary seismic response data and heavy structural damping shall not fulfil traditional Operational Modal Analysis assumptions, the present rFDD response‐only algorithm allows for the effective estimation of strong‐motion natural frequencies, mode shapes, and modal damping ratios, with real seismic response signals. The present rFDD enhancement derives from a preprocessing time‐frequency analysis and from an integrated approach for Power Spectral Density matrix computation, which constitute crucial innovative issues for the treatment of real earthquake response data. A monitoring case study is analysed by taking the real strong‐motion response records from a seven‐storey reinforced concrete building in Van Nuys, California, from 1987 to the latest 2014 events (Center of Engineering Strong Motion Data database), as recorded before, during and after the 1994 Northridge earthquake, which severely damaged the building (then retrofitted). This paper proves the effectiveness of the proposed enhanced rFDD algorithm as a robust method for monitoring current structural modal properties under real earthquake excitations. This shall allow for identifying possible variations of structural features along experienced seismic histories, providing then a fundamental tool towards Earthquake Engineering and Structural Health Monitoring purposes.

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Modal identification of damaged frames

Cited by 10 publications

References 36 publications

Modal identification of localised damage in beams and trusses: experimental and numerical results

Modal identification of localised damage in beams and trusses: experimental and numerical results

Dynamic damage identification using complex mode shapes

Seismic FDD modal identification and monitoring of building properties from real strong-motion structural response signals

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