On the origin of the cracks in the dome of the Pantheon in Rome

Abstract

In this paper we aim at giving a contribution to a problem that has been the subject of previous studies since some decades: the reason and period of formation of the meridional cracks that affect the dome of the Pantheon of Rome. This problem is investigated using a detailed three-dimensional finite-element simulation in which material nonlinearities, as well as a plausible sequence of the construction stages, are modeled. In particular, we show that concrete shrinkage, together with gravity may have been the main mechanical causes of the cracks in the early phases of the building's life. Unlike previous studies on the matter, that have largely inspired our research and where simplified 2D finite element models of the Pantheon were used, we make use of a detailed 3D model of the Pantheon's structure, that takes into account for both the particular geometry of the building, and namely the presence in the dome of a coffering and of caveas, and of the differences in the materials. The nonlinear numerical simulations, in addition, aim at reproducing, through different steps, the (probable) true constructing sequence of the dome, in order to obtain numerical results as much as possible close to reality. The results of our simulations show a rather surprising correspondence with the actual state of the dome: in fact, the overall pattern of the cracks so found is in a very good agreement with the real one, for both the number of the cracks and their extent, which shows that concrete shrinkage may have been the true reason for the presence of the meridional cracks. We have also investigated the role of the stepped rings that exist in the outer part of the dome; we show in this case that some previous studies are not necessarily contradictory, but rather complementary.

Ancient restorations: computer-based structural approach for the identification and reinterpretation of the Medracen’s constructive sequence

“…However, as for ancient buildings, mainly those with basic geometry (such as the Pyramids), computer-based analysis-diagnosis studies are less presented (see, e.g. Giannattasio, Grillo & Murru, 2016;Aguilar et al, 2017;Masi, Stefanou & Vannucci, 2018;Giaccone, 2020). They are rather studied through virtual reconstruction for informationcommunication aims as they are considered as totally or partially lost buildings and artefacts (Younes et al, 2017;Stampouloglou et al, 2019;García-León, González-García & Collado-Espejo, 2021).…”

Graphical Modelling of Hoop Force Distribution for Equilibrium Analysis of Masonry Domes

“…The cause of cracks could depend on several factors: excessive load, thermal alteration, etc. Among the several causes, the increasing of the span due to settling of the supports is one of the most common phenomena that leads to cracks (Masi et al 2018;Pavlovic et al 2016). Under these conditions, hemispherical or axisymmetric domes manifest cracks which start from the base, open along the meridian direction, and stop near the crown of the dome (Heyman 1967).…”

“…8). The dome, constructed in unreinforced concrete with coffering on the intrados (Aliberti and Alonso-Rodríguez 2017), is composed of different layers of aggregate; the one near the support has the highest specific weight (16.00 kN/m 3 ) and, like the thickness, it decreases with height (from 16.00 to 13.50 kN/m 3 ) (Masi et al 2018).…”

Resistance of museum artefacts against blast loading

“…The material constitutive law is modified accordingly: in tension, a linear elastic behaviour is assumed until the maximum principal stress reaches the tensile strength. A subsequent tensile softening is considered in terms of the nonlinear brittle cracking model [20,36,37]. In compression, the behaviour is assumed to be linearly elastic due to the lower compression stresses involved in the case at hand and the high (strain rate dependent) material strength.…”