Joint Layout Design: Finding the Strongest Connections within Segmental Masonry Arched Forms

Segmental arched forms composed of discrete units are among the most common construction systems, ranging from historic masonry vaults to contemporary precast concrete shells. Simple fabrication, transport, and assembly have particularly made these structural systems convenient choices to construct infrastructures such as bridges in challenging environmental conditions. The most important drawback of segmental vaults is basically the poor mechanical behaviour at the joints connecting their constituent segments. The influence of the joint shape and location on structural performances has been widely explored in the literature, including studies on different stereotomy, bond patterns, and interlocking joint shapes. To date, however, a few methods have been developed to design optimal joint layouts, but they are limited to extremely limited geometric parameters and material properties. To remedy this, this paper presents a novel method to design the strongest joint layout in 2D arched structures while allowing joints to take on a range of diverse shapes. To do so, a masonry arched form is represented as a layout of potential joints, and the optimization problems developed based on the two plastic methods of classic limit analysis and discontinuity layout optimization find the joint layout that corresponds to the maximum load-bearing capacity.

FROM TLS POINT CLOUD DATA TO GEOMETRICAL GENESIS DETERMINATION OF RIBBED MASONRY VAULTS

The contribution aims to explore the possibility of tracing the geometry of ribbed vaults from two different Mediterranean regions to a single matrix, verifying the presence of possible local variations of the same rules. In particular, the analyses are being carried out in parallel on some case studies of the regions of Sardinia in Italy and Aragon in Spain. The two case studies include the Iglesia Parroquial del Salvador la Seo in Zaragoza and the Church of Santa Lucia in Cagliari. Both constructions can be traced back to the style known as Late Mediterranean Gothic, which characterised the architecture of the countries bordering the Mediterranean basin between the 14th and 17th centuries. The two case studies chosen were almost at the extreme ends of the Late Gothic period, to determine whether some invariants sought could persist even in relatively distant periods. The analysis focused on cross vaults covering the two naves, which included a laser scanner survey in order to obtain a cloud of points of sufficient precision to carry out studies on the geometry of the vaulted systems, the identification of the intrados profiles of the ribs and therefore the definition of the curvatures and centres of all the arches making up the vaults. Finally, the results are presented by means of summary diagrams and comparison tables.

CRITERIA AND TOOLS TO CATALOGUE BRICK-MASONRY VAULTS. THE GIS-DATABASE OF FRAME, A FASCE AND PLANTERIAN VAULTS BETWEEN THE 16TH AND 18TH CENTURY IN NORTHERN ITALY

The paper describes a proposal for criteria and tools to catalogue brick-masonry vaulted systems in Northern Italy between the 16th and 18thcenturies. Along with the standard geometric typologies, three novel parameters (maîtresses voûtes, voûte sur le plan d'une autre voûte, constructive features) are proposed to include the constructive features in the vault taxonomy. The novel parameters help catalogue three vaulting types that can be considered the metamorphosis of cloister vaults: frame, a fasce, and planterian vaults. The database was realized in MS Access and then imported into QGIS 3.10. Database and GIS have been operative tools to form hypotheses on vault disseminations, highlighting the recurrences and specificities across time and space of some peculiar construction techniques. The database collects the acquired information on each vault (building type, geolocation, building date, vaulting type, vault dimensions and description and, whenever possible, photogrammetric survey, 3D modelling, and thermographic survey). In the future, the database should be published online, making the data available and building a broader dataset to share the information.

From Stress to Shape: Equilibrium of Cloister and Cross Vaults

The assessment of the equilibrium and the safety of masonry vaults is of high relevance for the conservation and restoration of historical heritage. In the literature many approaches have been proposed for this tasks, starting from the 17th century. In this work we focus on the Membrane Equilibrium Analysis, developed under the Heyman’s theory of Limit Analysis. Within this theory, the equilibrium of a vault is assessed if it is possible to find at least one membrane surface, between the volume of the vaults, being in equilibrium under the given loads through a purely compressive stress field. The equilibrium of membranes is described by a second order partial differential equation, which is definitely elliptic only when a negative semidefinite stress is assigned, and the shape is the unknown of the problem. The proposed algorithm aims at finding membrane shapes, entirely comprised between the geometry of the vault, in equilibrium with admissible stress fields, through the minimization of an error function with respect to shape parameters of the stress potential, and then, with respect to the boundary values of the membrane shape. The application to two test cases shows the viability of this tool for the assessment of the equilibrium of existing masonry vaults.

A combination of terrestrial laser-scanning point clouds and the thrust network analysis approach for structural modelling of masonry vaults

Terrestrial laser-scanning (TLS) is well suited to surveying the geometry of monumental complexes, often realised with highly irregular materials and forms. This paper addresses various issues related to the acquisition of point clouds via TLS and their elaboration aimed at developing structural models of masonry vaults. This structural system, which exists in numerous artifacts and historical buildings, has the advantages of good static and functional behaviour, reduced weight, good requisites of insulation, and aesthetic quality. Specifically, using TLS, we create a geometric model of the ancient masonry church, S. Maria della Libera, in Aquino, largely characterised by naves featuring cross vaults and previously used as a case study in the paper entitled ‘Terrestrial laser-scanning point-clouds for modeling masonry vaults’, presented at the 2019 IMEKO TC-4 International Conference on Metrology for Archaeology and Cultural Heritage. The results of the TLS survey are used as input for a structural analysis based on the thrust network analysis. This recent methodology is used for modelling masonry vaults as a discrete network of forces in equilibrium with gravitational loads. It is demonstrated that the proposed approach is both effective and robust in terms of assessing not only the safety conditions of existing masonry vaults, the actual geometry of which significantly influences the safety level, but also to design new ones.