Relations between static-structural aspects, construction phases and building materials of San Saturnino Basilica (Cagliari, Italy)

The construction site was used several times: in a first phase, in the republican era of Roman domination it hosted, probably, a temple whose height could reach 25 meters; in a second phase, during the Roman Empire, it was used as a burial area. Then around IV-V century AD a first Christian Basilica made of a naved building with an apse was built there, at the center of a large monastery. Subsequently in a third phase in VI century AD a Byzantine Martyrium, with a Greek cross-shaped plan, was built: the central part of it, supporting a dome is still standing. Finally after 1089 the church was given to Marsilian monks who deeply renovated it and changed its shape converting the plan to a Latin cross. A macroscopic material analysis shows the presence of various rocks, whose use appears to be inhomogeneous during all construction phases. Sedimentary rocks (limestones, sandstones, calcarenites etc belonging to local geological formations) are generally used for masonry structures. Marbles, mostly coming from abroad and previously used in Roman buildings have been adopted for architectural elements (columns, capitals, and so on). At a lower extent there are masonry blocks in Oligo-Miocenic volcanic rocks and seldom stone materials which are not originally from Sardinia. Both mineralogical and petrographic tests (e.g. XRF, XRD) and the most important physical properties (porosity, density, water absorption coefficients, compressive, flexural and tensile strength, etc) show that many of the more representative samples of rock materials (like limestonss, calcarenits) are often highly decayed, with a corresponding reduction of their mechanical strength. A structural analysis is particularly useful for helping in clarifying the historical evolution of the building, checking reconstruction hypotheses and assessing the true residual strength of the more important parts. An example, a FEM analysis of the Byzantine domed part is presented here

Chapter Lake Garda lemon houses: a mediterranean landscape in an internal lake

Lemon houses (limonaie) are ancient terraced citrus gardens that shape the landscape along the NW shore of Lake Garda (Northern Italy). We propose an interpretation of limonaie as a deeply anthropogenic, labour intensive, multifunctional landscape that shares many characteristics with the oases of the wider Mediterranean basin. Any intervention which aims at preserving the fragility and peculiarity of the area, as well as the intangible cultural heritage of the citrus cultivation, should be framed in a holistic agroecosystemic perspective, deeply rooted in the knowledge of the limonaie past

Stabilization by deflation for sparse dynamical systems without loss of sparsity

Multiple-input, multiple-output models for coupled systems in structural dynamics including unbounded domains, like soil or fluid, are characterized by sparse system-matrices and unstable parts in the whole set of solutions due to spurious modes. Spectral shifting with deflation can stabilize these unstable parts; however the originally sparse system-matrices become fully populated when this procedure is applied. This paper presents a special consecutive treatment of the deflated system without losing the numerical advantages from sparsity. The procedure starts with an LU-decomposition of the sparse undeflated system and continues with restricting the solution space with respect to deflation using the same LU-decomposition. An example from soil-structure interaction shows the benefits of this consecutive treatment

Contact interactions in complex fibrous metamaterials: a proposal for elastic energy and Rayleigh dissipation potential

In this work, an extension of the strain energy for fibrous metamaterials composed of two families of parallel fibers lying on parallel planes and joined by connective elements is proposed. The suggested extension concerns the possibility that the constituent fibers come into contact and eventually scroll one with respect to the other with consequent dissipation due to friction. The fibers interact with each other in at least three different ways: indirectly, through microstructural connections that could allow a relative sliding between the two families of fibers; directly, as the fibers of a family can touch each other and can scroll introducing dissipation. From a mathematical point of view, these effects are modeled first by introducing two placement fields for the two fiber families and adding a coupling term to the strain energy and secondly by adding two other terms that take into account the interdistance between the parallel fibers and the Rayleigh dissipation potential (to account for friction)

The construction materials and static-structural aspects of the Budello tower (Teulada, southwest Sardinia, Italy)

[EN] The Budello tower is located on a slight promontory from which it dominates the entire bay of Teulada and the towers of Sant’Isidoro, Pixinni, Malfatano and Porto Scudo. The tower, built in 1601 with irregular ashlars of local stones (mainly of magmatic-intrusive origin), has a truncated cone shape, an external diameter of 10,2 m and a height of 11,80 m. Inside it consists of a single room, with a domed vault and a central pillar, equipped with a embrasure, a fireplace, a trap door in the cistern, and a staircase, from which the square of arms was accessed. It was a torre de armas garrisoned by: 1 commander (in 1603), 1 artilleryman and 4 soldiers (1767), 1 artilleryman and 3 soldiers (1801), 1 artilleryman and 4 soldiers (1812). Although it underwent several restorations, documented as early as the years 1617-1619, the tower remained generally in good condition until the period 1763-1784, in which new restoration works were carried out including the closure of the parade ground with a classic parapet with gunboats and battlements. Other restoration works are carried out in 1808, 1819 and 1840. The tower remained in operation until 1843. Like all the other coastal fortifications, it was then definitively demilitarized with the Regio Decreto of 25 April 1867. Specific objectives of the research are the petrographic and physical-mechanical analysis of the stones and ancient mortars used in the construction of the tower, the structural analysis of the building and related geometric-constructive characteristics. The final intention is to understand the decay processes taking place on the tower both in terms of materials and static-structural aspects, and to envisage possible restoration interventions to be implemented aimed at its conservation.Columbu, S.; Picchizzolu, G.; Cazzani, A. (2020). The construction materials and static-structural aspects of the Budello tower (Teulada, southwest Sardinia, Italy). Editorial Universitat Politècnica de València. 1485-1492. https://doi.org/10.4995/FORTMED2020.2020.11549OCS1485149

THE GEO-REFERENCED XIX CENTURY CARTOGRAPHY: AN ANALYSIS TOOL AND A PROJECT REFERENCE FOR THE PRESERVATION AND MANAGEMENT OF BUILT AND LANDSCAPE HERITAGE

Abstract. Considering built and landscape heritage, the paper demonstrates how it is necessary to conserve the historic stratification and to define new compatible plans and uses, identifying the ways to mitigate alteration impacts, requalify degraded areas, enhance natural, historic and cultural values, improve documentary and educational options, and manage new tasks and opportunities. Particularly, the historic complexity of built and landscape heritage, and the level of permanence can be recognized and evaluated by comparing multi-temporal historic and current maps, and surveying the present situation in order to define preservation strategies.Innovative tools (open source map registry, open source GIS data management) support the critical analysis of the maps, the representation of historic stratification, the evaluation of conservation levels, and the definition of heritage reuse and management. Moreover, innovative applications based on advanced Virtual Hub, when used to publish historical maps as Open Data (GEOPAN ATL@S APP), allow a larger public of non-expert users (tourists, citizens, bikers, students, etc.) to access the extraordinary richness of the historical map contents, and navigate across urban landscapes. Such APPs are thus becoming instruments of awareness with a strong pro-active capacity to stimulate new design plans encompassing local cultural identity and rediscovering traces of the past.</p

An analytical assessment of finite element and isogeometric analyses of the whole spectrum of Timoshenko beams

The theoretical results relevant to the vibration modes of Timoshenko beams are here used as benchmarks for assessing the correctness of the numerical values provided by several finite element models, based on either the traditional Lagrangian interpolation or on the recently developed isogeometric approach. Comparison of results is performed on both spectrum error (in terms of the detected natural frequencies) and on the l2 relative error (in terms of the computed eigenmodes): this double check allows detecting for each finite element model, and for a discretization based on the same number of degrees-of-freedom, N, the frequency threshold above which some prescribed accuracy level is lost, and results become more and more unreliable. Hence a quantitative way of measuring the finite element performance in modeling a Timoshenko beam is proposed. The use of Fast Fourier Transform is finally employed, for a selected set of vibration modes, to explain the reasons of the accuracy decay, mostly linked to a poor separation of the natural frequencies in the spectrum, which is responsible of some aliasing of modes

On the whole spectrum of Timoshenko beams. Part I: a theoretical revisitation

The problem of free vibrations of the Timoshenko beam model is here addressed. A careful analysis of the governing equations allows identifying that the vibration spectrum consists of two parts, separated by a transition frequency, which, depending on the applied boundary conditions, might be itself part of the spectrum. For both parts of the spectrum, the values of natural frequencies are computed and the expressions of eigenmodes are provided. This allows to acknowledge that the nature of vibration modes changes when moving across the transition frequency. Among all possible combination of end constraints which can be applied to single-span beams, the case of a simply supported beam is considered. These theoretical results can be used as benchmarks for assessing the correctness of the numerical values provided by several numerical techniques, e.g. traditional Lagrangian-based finite element models or the newly developed isogeometric approach

On the whole spectrum of Timoshenko beams. Part II: Further applications

The problem of free vibrations of the Timoshenko beam model has been addressed in the first part of this paper. A careful analysis of the governing equations has shown that the vibration spectrum consists of two parts, separated by a transition frequency, which, depending on the applied boundary conditions, might be itself part of the spectrum. Here, as an extension, the case of a doubly clamped beam is considered. For both parts of the spectrum, the values of natural frequencies are computed and the expressions of eigenmodes are provided: this allows to acknowledge that the nature of vibration modes changes when moving across the transition frequency. This case is a meaningful example of more general ones, where the wave-numbers equation cannot be written in a factorized form and hence must be solved by general rootfinding methods for nonlinear transcendental equations. These theoretical results can be used as further benchmarks for assessing the correctness of the numerical values provided by several numerical techniques, e.g. finite element models

On nonlinear dilatational strain gradient elasticity

We call nonlinear dilatational strain gradient elasticity the theory in which the specific class of dilatational second gradient continua is considered: those whose deformation energy depends, in an objective way, on the gradient of placement and on the gradient of the determinant of the gradient of placement. It is an interesting particular case of complete Toupin–Mindlin nonlinear strain gradient elasticity: indeed, in it, the only second gradient effects are due to the inhomogeneous dilatation state of the considered deformable body. The dilatational second gradient continua are strictly related to other generalized models with scalar (one-dimensional) microstructure as those considered in poroelasticity. They could be also regarded to be the result of a kind of “solidification” of the strain gradient fluids known as Korteweg or Cahn–Hilliard fluids. Using the variational approach we derive, for dilatational second gradient continua the Euler–Lagrange equilibrium conditions in both Lagrangian and Eulerian descriptions. In particular, we show that the considered continua can support contact forces concentrated on edges but also on surface curves in the faces of piecewise orientable contact surfaces. The conditions characterizing the possible externally applicable double forces and curve forces are found and examined in detail. As a result of linearization the case of small deformations is also presented. The peculiarities of the model is illustrated through axial deformations of a thick-walled elastic tube and the propagation of dilatational waves