Santa Maria di Collemaggio Church (L’Aquila,Italy): Historical Reconstruction by Non-Destructive Testing Techniques

The main goal of this work was the non-destructive testing (NDT) of an ancient fresco (15th century) preserved in the Santa Maria di Collemaggio Church (L’Aquila, Italy) and damaged after the 2009 earthquake. Active infrared thermography (IRT), near-infrared (NIR) reflectography and ultraviolet imaging (UV) were used. In addition, the state of the fresco prior to the earthquake was analyzed by electronic speckle pattern interferometry (ESPI), digital speckle correlation (DSC), raking light, tap, and chemical NDT techniques. The use of these techniques was important for the monitoring of new damages and for a comparison between the results over the years. Square heating thermography (SHT) data were processed using principal component thermography (PCT) and pulsed phase thermography (PPT) algorithms, in order to improve the defects’ signature and to reduce the impact of non-uniform heating and emissivity variations due to the painting’s pigments. A multi-analysis approach, segmentation operators and a specific data correlation method emphasize the overall study of the fresco. Furthermore, the facade and the high altar area were inspected by passive thermography and ground-penetrating radar (GPR), respectively. In the present case, the combined use of NDT techniques was useful to fill in the gaps in the construction history of the building.     

The Bell-Tower Facade: An Aseismic Device in Sicily Between the 12th and 18th Centuries

Imposing tower facades with belfries in the last order were built in Sicily Italy, from the Middle Ages to the late Baroque period. Until the 16th century, this model, which was inspired by northern European examples, also had a parallelepiped forepart leaning against the facade, working as containment for the pressure imparted by the inner longitudinal arches on the front, and amplified in case of earthquakes. The lacking static efficiency of these early structures is demonstrated by collapses during the strong earthquakes that hit the island in the modern age. Despite numerous cases of destruction, the memory of some prototypes survived in Sicilian constructive memory through the elaboration, in the late Baroque, of tower facades with an updated morphology. The hybridization with Guarini’s pyramid scheme, and its related articulations, could in fact offer the tower system advantages in terms of structural strength, thanks to a better balanced redistribution of masses and weights.