Abstract

Investigation into the geometric configuration of historical masonry domes isfundamental when studying the structural behaviour of these architectural elements, above all if they have historical and artistic relevance. Indeed, accurate geometric information is essential also for the construction of reliable mechanical models, to monitor the condition stateof the building and to plan strengthening and conservation interventions. To this aim, a multidisciplinary approach is required to collate the highest possible amount of data useful for the numerical modelling, including historical and archival research. The "SS. Trinità" church is a 16th century building of great historical, architectural and structural significance in the historic centre of Turin. It owes its fame primarily to the architect who built it, Ascanio Vitozzi, and to its large dome, built after the architect’s death. The availability of a recently undertaken laser scanner survey of the intrados of the dome made it possible to detect several depressions of the masonry cap. These findings can be either due to construction defects, or to structural problems that developed over centuries, or to the severefire which struck the dome in 1942. In this multidisciplinary research, different numerical models of the masonry dome of SS.Trinità church were built. As a first step, a geometric study was based on the point cloud from the laser scanning. Then, structural analyses were conducted on the two different models of the dome-tambour system of the building, in order to try to explain the observed deformation behaviour.

Abstract

Masonry vaults have a great diffusion in the historical architectural heritage: in this work, their structural behavior is investigated. Attention is focused on lowered sail vaults composed by several brick arrangements, a typical nineteenth-century masonry vault which have great diffusion in Cagliari (Sardinia). The target is evaluating the role played by bricks arrangement in their mechanical behavior. A series of rigorous laser scanner surveys have been performed in order to obtain the effective geometry both at macro-level – the vault shape – and at micro-level – brick patterns. A NURBS (Non-Uniform Rational B Spline) representation of the geometry is adopted and adaptive upper bound limit analyses are performed. NURBS entities, which are common in commercial CAD packages, have the great advantage to describe complex geometries such as curved elements, with very few elements. An upper bound limit analysis formulation is adopted, in which the NURBS elements forming the mesh are idealized as rigid bodies with dissipation allowed only along interfaces. The mesh constituted by few NURBS elements is progressively adjusted through a genetic algorithm in order to minimize the live load multiplier. Limit analysis is performed initially to determine the collapse multiplier of vertical loads, to assess the load bearing capacity of the vault, then attention is focused on differential settlements, that may be a serious hazard for this structural typology.

Abstract

The parish church of “Santa Maria” is considered one of the most important medieval buildings of Arezzo Although the church is attested from 11th century, it is between the 13th and 14th centuries that reached its current consistency, characterized by the particular façade with small columns on several levels and an imposing bell tower. Later, from the 16th to the 18th century, the church underwent profound transformations, that were almost completely erased by extensive restoration works in the second half of the 19th century. The architectural survey of the parish church of “Santa Maria” was carried out with a phase-shift laser scanner and a digital reflex camera (Z+F 5006h). 189 scans were performed for generating the 3D model of the church: 180 of them with high density and normal quality, lasting 5-6 minutes; the remaining ones with super high density and high quality, lasting 13-14 minutes. Vectorial drawings of plans and sections were then created from the 3D model. Thanks to laser scanner survay of the chuch, it was possible to highlight the singularity of the structure of the basilical body and the transept. The tilt of walls and columns, the variations in the thickness of the walls, the considerable deformations of some arches, the cracks and textures of the wall facing were thus shown. The information obtained attested an architectural structure created by complex construction events that over time have affected this building. The cnstructive singularities involve the medieval genesis of the building, the transformations during the following centuries and the following restoration works. These composite features are specific and common to every ancient building. This peculiar epistemological condition eschews from simplifications and requires deep and complex studies closely linked to the problems of conservation of the structures.