Prediction of cracking evolution in full scale structures by the b-value analysis and Yule statistics

As a case study we present the method used by the authors to determine the conditions of the materials and the crack patterns in the structures of the Syracuse Cathedral, built in the 17th century on the structures of the ancient Greek “Temple of Athena” (5th century B.C.). In particular, the acoustic emission technique was used to evaluate the onset of critical conditions in a monitored pillar, which is part of the vertical load-bearing structures. The b-value trends are shown by several acoustic emission tests carried out on specimens of different dimensions extracted from the pillar. In addition, these results are compared to the acoustic emission data obtained from the in situ monitored pillar; it is shown that the b-value can be used both in the laboratory specimens and in the in situ measurements as a reliable indicator of the structural integrity.