Rehabilitation assessment of a centenary steel bridge based on modal analysis

Costa, Bruno J. Afonso; Magalhães, Filipe; Cunha, Álvaro; Figueiras, Joaquim

doi:10.1016/j.engstruct.2013.05.010

Cited by 18 publications

(8 citation statements)

References 15 publications

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“…For illustrative purposes, one set of the five strain and acceleration responses of the controlled traffic test, covering data before and after the truck entered the bridge at the speed of 20 km/h, is depicted in Figure 4. In comparison with large-scale bridges, where the root mean square (RMS) acceleration responses are usually around 0.05 m/s 2 , [42][43][44][45][46] the acceleration responses captured on this bridge are about 5 to 10 times smaller. This is reasonable considering a higher stiffness of this bridge compared with those more flexible bridges.…”

Section: Controlled Traffic Testmentioning

confidence: 77%

Field test investigations for condition monitoring of a concrete culvert bridge using vibration responses

Lin

Alamdari

et al. 2020

Struct Control Health Monit

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Summary Over the last two decades, vibration‐based structural health and condition monitoring has gradually become one of the main methods for monitoring changes in a structure on a global scale. This method has been applied to damage detection in many areas, including aerospace, mechanical and structural systems. However, it has not been widely used for identifying condition change of the structure itself. This paper demonstrates the feasibility of utilising acceleration and strain responses measured from a short‐span concrete culvert bridge located in New South Wales, Australia, to identify the effects of structural condition changes made to the deck due to bridge widening. In addition to the operating structural responses, two controlled traffic tests were carried out, before and after the bridge widening, in support of verifying the results from the modal analysis. A comparative study is presented evaluating the results obtained by two identification algorithms, namely, frequency‐domain decomposition (FDD) and frequency–spatial domain decomposition (FSDD), from which the link between the decrease in modal frequency and the event of bridge expansion as condition change is successfully established. The contribution of this work is to emphasise the application of FDD and FSDD on a short‐span concrete culvert bridge, in order to drive the interest from large‐scale bridges to short‐span bridges so as to increase the coverage of current bridge health monitoring.

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Section: Controlled Traffic Testmentioning

confidence: 77%

Field test investigations for condition monitoring of a concrete culvert bridge using vibration responses

Lin

Alamdari

et al. 2020

Struct Control Health Monit

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“…Although this assumption may seem drastic, one may think of it as replacing the stochastic dependence between and by deterministic dependencies between their relevant moments [22]. Following this assumption and assigning independent prior distributions for and , we have (4) where denotes the expectation operator with respect to the joint distribution of and . Thus, in order to maximize the free energy , we have to reduce the KL divergences between the approximating and prior distributions and simultaneously increase the expected log conditional likelihood.…”

Section: Variational Bayesmentioning

confidence: 99%

“…They are directly related to the mass and stiffness distributions, which are influenced by changes in support and continuity conditions as well as material properties. Identification of modal parameters has become a standard tool for model updating [1], structural control [2], damage detection [3] and condition assessment [4].…”

Section: Introductionmentioning

confidence: 99%

Operational modal identification using variational Bayes

Kiureghian

2017

Mechanical Systems and Signal Processing

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Operational modal analysis is the primary tool for modal parameter identification in civil engineering. Bayesian statistics offers an ideal framework for analyzing uncertainties associated with the identified modal parameters. However, the exact Bayesian formulation is usually intractable due to the high computational demand in obtaining the posterior distributions of modal parameters. In this paper, the variational Bayes method is employed to provide an approximate solution. Unlike the Laplace approximation and Monte Carlo sampling, the variational Bayes approach provides a gradient-free algorithm to analytically approximate the posterior distributions. Working with the state-space representation of a dynamical system, the variational Bayes approach for identification of modal parameters is derived by ignoring statistical correlation between latent variables and the model parameters. In this approach, the joint distribution of the state-transition and observation matrices as well as the joint distribution of the process noise and measurement error are firstly calculated analytically using conjugate priors. The distribution of modal parameters is extracted from these obtained joint distributions using a first-order Taylor series expansion. A robust implementation of the method is discussed by using square-root filtering and Cholesky decomposition. The proposed approach is illustrated by its application to an example mass-spring system and the One Rincon Hill Tower in San Francisco.

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“…These techniques exploit ambient acceleration records to extract the modal features of the system, namely, the natural frequencies, mode shapes and damping ratios. 4,5 The impact of these techniques on the monitored structures is kept minimal, and plenty of successful applications to diverse historic structures can be found in the literature, including bridges, 6,7 towers, 8,9 churches 10 and buildings. 11,12 Given that the modal features depend upon the stiffness, mass distribution and boundary conditions of the structure, damage detection through OMA can be performed by tracking variations in the identified modal parameters.…”

Section: Introductionmentioning

confidence: 99%

Synergistic application of operational modal analysis and ambient noise deconvolution interferometry for structural and damage identification in historic masonry structures: three case studies of Italian architectural heritage

García‐Macías

Kita

Ubertini

2019

Structural Health Monitoring

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Conservation techniques within the framework of structural health monitoring, particularly through dynamic measurements and operational modal analysis, are becoming popular for condition-based maintenance and decision-making in historic structures. Nonetheless, while effective for giving insight into the overall behaviour of structures, these techniques may fail at detecting local damages with limited effects on the modal features of the system. In this regard, the analysis of propagating waves throughout the structure poses an attractive alternative for data-driven damage identification. Specifically, some encouraging results have been reported on the application of seismic interferometry to reinforced concrete structures, albeit the number of works concerning ambient vibrations is far scarce, and practically nonexistent in the realm of historic structures. In this light, this article explores the synergistic application of operational modal analysis and ambient noise deconvolution interferometry for the structural identification of historic structures through three different case studies, namely the Sciri Tower in Perugia, the Consoli Palace in Gubbio and the bell-tower of the Basilica of San Pietro in Perugia. The first case study represents a typical example of a masonry tower inserted into a building aggregate, while the second one constitutes a particular case of a monumental masonry palace. The presented results and discussion cover diverse aspects of the identification of wave velocities, signal processing strategies, effects of dispersion and robustness of the identification. Finally, the case study of the bell-tower of the Basilica of San Pietro illustrates the application of operational modal analysis and deconvolution interferometry for damage identification. To do so, two different ambient vibration tests conducted before and after the 2016 Central Italy seismic sequence are studied. The results show concentrated reductions in the wave velocities in the area of the belfry, which demonstrates that deconvolution interferometry constitutes a complementary technique to operational modal analysis for damage localization and, to some extent, damage quantification.

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Rehabilitation assessment of a centenary steel bridge based on modal analysis

Cited by 18 publications

References 15 publications

Field test investigations for condition monitoring of a concrete culvert bridge using vibration responses

Field test investigations for condition monitoring of a concrete culvert bridge using vibration responses

Operational modal identification using variational Bayes

Synergistic application of operational modal analysis and ambient noise deconvolution interferometry for structural and damage identification in historic masonry structures: three case studies of Italian architectural heritage

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