Abstract

We address the problem of damage identification in complex civil infrastructure with an integrative modular Bayesian framework. The proposed approach uses multiple response Gaussian processes to build an informative yet computationally affordable probabilistic model, which detects damage through inverse updating. Performance of structural components associated with parameters of the developed model was quantified with a damage metric. Particular emphasis is given to environmental and operational effects, parametric uncertainty and model discrepancy. Additional difficulties due to usage of costly physics-based models and noisy observations are also taken into account. The framework has been used to identify a reduction of a simulated cantilever beam elastic modulus, and anomalous features in main/stay cables and bearings of the Tamar bridge. In the latter case study, displacements, natural frequencies, temperature and traffic monitored throughout one year were used to form a reference baseline, which was compared against a current state, based on one month worth of data. Results suggest that the proposed approach can identify damage with a small error margin, even under the presence of model discrepancy. However, if parameters are sensitive to environmental/operational effects, as observed for the Tamar bridge stay cables, false alarms might occur. Validation with monitored data is also highlighted and supports the feasibility of the proposed approach.

Highlights

  • A structural health monitoring (SHM) system must be able to identify the performance of complex physical systems

  • Based on the above remarks, the current paper proposes a hybrid modular Bayesian approach (MBA) to address the damage identification problem

  • It is recalled that the module 2 of the MBA, approximation of the discrepancy function, requires marginalisation of the computer model multiple response Gaussian processes (mrGp) with respect to the parameters prior

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Summary

Introduction

A structural health monitoring (SHM) system must be able to identify the performance of complex physical systems. One is Journal of Civil Structural Health Monitoring (2019) 9:201–215 the environmental/operational effects— known as confounding influences—which mask the presence and extent of damage This is a well known and extensively documented problem [11, 16, 17, 35]. Unless the effects of model discrepancy are small, assuming them as a zero-mean uncorrelated Gaussian [37, 43] (as in the traditional Bayesian methods) results in biased identifications. For these reasons, the broad influence of environmental variations, and in particular temperature, lead to the development of several temperature-based damage identification methods.

Modelling assumptions
Damage identification
Numerical example of a cantilever beam
The Tamar bridge reference and current state datasets
Stiffness of bearings arrangements
Initial strain of main suspension cables
Findings
Initial strain of stay cables

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