Browsing by Author "Royer-Carfagni, Gianni"

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A regularized non-smooth contact dynamics approach for architectural masonry structures
(PERGAMON-ELSEVIER SCIENCE LTD, THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND, 2017) Beatini, Valentina; Royer-Carfagni, Gianni; Tasora, Alessandro; AGÜ, Mimarlık Fakültesi, Mimarlık Bölümü;
A Non-Smooth Contact Dynamic (NSCD) formulation is used to analyze complex assemblies of rigid blocks, representative of real masonry structures. A model of associative friction sliding is proposed, expressed through a Differential Variational Inequality (DVI) formulation, relying upon the theory of Measure Differential Inclusion (MDI). A regularization is used in order to select a unique solution and to avoid problems of indeterminacy in redundant contacts. This approach, complemented with an optimized collision detection algorithm for convex contacts, results to be reliable for dynamic analyses of masonry structures under static and dynamic loads. The approach is comprehensive, since we implement a custom NSCD simulator based on the Project Chrono C++ framework, and we design custom tools for pre-and post-processing through a user-friendly parametric design software. Representative examples confirm that the method can handle 3-D complex structures, as typically are architectural masonry constructions, under both static and dynamic loading. (C) 2017 Elsevier Ltd. All rights reserved.
The role of frictional contact of constituent blocks on the stability of masonry domes
(ROYAL SOC, 6-9 CARLTON HOUSE TERRACE, LONDON SW1Y 5AG, ENGLAND, 2018) Beatini, Valentina; Royer-Carfagni, Gianni; Tasora, Alessandro; AGÜ, Mimarlık Fakültesi, Mimarlık Bölümü;
The observation of old construction works confirms that masonry domes can withstand tensile hoop stresses, at least up to a certain level. Here, such tensile resistance, rather than a priori assumed as a property of the bulk material, is attributed to the contact forces that are developed at the interfaces between interlocked blocks under normal pressure, specified by Coulomb's friction law. According to this rationale, the aspect ratio of the blocks, as well as the bond pattern, becomes of fundamental importance. To investigate the complex assembly of blocks, supposed rigid, we present a non-smooth contact dynamic analysis, implemented in a custom software based on the Project Chrono C++ framework and complemented with parametric-design interfaces for pre- and post-processing complex geometries. Through this advanced tool, we investigate the role of frictional forces resisting hoop stresses in the stability of domes, either circular or oval, under static and dynamic loading, focusing, in particular, on the structural role played by the underlying drumand the surmounting tiburium.
Soap film analogy for anisotropically stretched membranes and cable nets
(SPRINGERONE NEW YORK PLAZA, SUITE 4600 , NEW YORK, NY 10004, UNITED STATES, 2017) Beatini, Valentina; Royer-Carfagni, Gianni; AGÜ, Mimarlık Fakültesi, Mimarlık Bölümü; Beatini, Valentina
Analogical physical models are a preferred technique to intuitively grasp complex engineering problems. It is well-known that the equilibrium minimal-surface configuration of membranes under equibiaxial tension can be visually represented by the surface of a soap film under equivalent boundary conditions, but this analogy fails when the stress state is not uniform equibiaxial. We extend to this situation the analogy with soap films. The equilibrium state of an orthotropically tensioned membrane is found by geometrically stretching the shape of a soap film, in a precise manner depending upon the applied state of stress. The procedure is easily done by elaborating digital pictures. The method is mathematically justified under the kinematic hypotheses of small strains and large rotations, and further verified in a parametric design environment. It can also provide an insight into the equilibrium configuration of cable-nets, when the stresses in the warp and weft directions are considerably different. Furthermore, this visualization favors implementing transformable shapes for membranes or orthogonal cable nets, as a consequence of a modification of the ratio of the principal stress components.