Assessment of structural interventions using Bayesian updating and subspace-based fault detection methods: the case study of S. Maria di Collemaggio basilica, L’Aquila, Italy

Abstract

The article focuses on the assessment of a structural intervention using a simple Bayesian approach driven by subspace-based indicators. A permanent monitoring system installed in a monumental masonry structure, the basilica of Santa Maria di Collemaggio in L’Aquila Italy, continuously acquires vibration data. The results of modal identification are first reported and discussed. Then, the article delivers a damage detection procedure, tested on two sets of data measured by the façade accelerometers before and after the CLT (Cross-Lam Timber) roof connection, which are interpreted as damage and reference states, respectively. The application of Bayesian inference to a set of damage indicators for the assessment of the façade structural modification is presented and compared with the results of a non-parametric ${\chi }^2$-tests. A computation procedure for the built of a statistical reference model is proposed by discussing the issue of the choice of the reference data set.

Keywords:

• Damage assessment
• dynamic tests
• earthquake engineering
• masonry
• risk and probability analysis

Acknowledgements

The authors thank ENI for having financed the structural rehabilitation and the monitoring system, giving back to the city of L’Aquila one of the most identifying monument.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes

1 On April 6th, 2009, at 3:32 a.m. an earthquake (Richter Magnitude 5.9) struck L’Aquila (Central Italy): 309 victims, 65,000 displaced people. More than 10 billion Euro of estimated damage, about 100 churches uninhabitable for the the old town centres

2 vec denotes the vectorization operator.

3 The indicators thresholds I_T do not correspond to Damage Limit States or Damage thresholds.