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

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 χ2 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.