Iannuzzo, Antonino (2017) A New Rigid Block Model for Masonry Structures. [Tesi di dottorato]


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Item Type: Tesi di dottorato
Lingua: English
Title: A New Rigid Block Model for Masonry Structures
Iannuzzo, Antoninoantoninoiannuzzo@libero.it
Date: 10 April 2017
Number of Pages: 293
Institution: Università degli Studi di Napoli Federico II
Department: Strutture per l'Ingegneria e l'Architettura
Dottorato: Ingegneria strutturale, geotecnica e sismica
Ciclo di dottorato: 29
Coordinatore del Corso di dottorato:
Rosati, Lucianorosati@unina.it
Gesualdo, AntonioUNSPECIFIED
Angelillo, MaurizioUNSPECIFIED
Date: 10 April 2017
Number of Pages: 293
Uncontrolled Keywords: New Rigid Block model, PR method, C0 method, masonry structures, unilateral materials, NRNT, smeared and concentrated cracks, limit analysis, settlements, horizontal actions
Settori scientifico-disciplinari del MIUR: Area 08 - Ingegneria civile e Architettura > ICAR/08 - Scienza delle costruzioni
Date Deposited: 25 Apr 2017 22:10
Last Modified: 13 Mar 2018 08:05
URI: http://www.fedoa.unina.it/id/eprint/11732
DOI: 10.6093/UNINA/FEDOA/11732


This dissertation presents a new rigid block model for the analysis of masonry elements and structures. In this work a masonry structure is modelled as a continuum composed by Normal Rigid No-Tension (NRNT) material. The NRNT represents an extension of the model material of Heyman to 2d/3d continua. The material is rigid in compression, but extensional deformations, allowed at zero energy price, can be either regular or singular; then extensional deformation can appear as either diffuse (smeared cracks) or concentrated (macroscopic cracks), and there is not any reason to prefer one upon another, on an energy ground. The fact that rigid block deformation seems to be the preferred failure mode for real masonry structures stems from mechanical characteristics, such as toughness, interlocking, finite friction and cohesion, that are not inherent to the simplified NRNT continuum model. So, it is interesting to see if rigid block mechanisms can arise naturally in solving the equilibrium problem, and if there is any legitimate way to force rigid block mechanisms over diffuse cracking. The boundary value problem for a continuum composed of NRNT material is formulated as an energy minimum search, and two numerical methods for approximating the solution are proposed. With the PR method the energy is minimized in the set of piecewise-rigid (PR) displacements. With the C0 method the possibility to restrict the search of the minimum to continuous (C0) displacement fields, by adopting some classical Finite Element (FE) approximation, is explored. The C0 solution, though more cumbersome from the numerical point of view, appears as more adaptable than the rigid block approximation, in approximating fracture lines that are slanted, that is far from being located on the skeleton of a mesh. This sluggishness of the rigid block approximation in reproducing “slanted” cracks (that is cracks not developing along the boundary of the rigid elements), is one of the main critical issues inherent to the piecewise rigid (PR) approximation. Then there is another reason to adopt the C0 approximation, namely for seeing if the C0 approximation can be used, in combination with the PR approximation, as a preliminary analysis for suggesting the optimal rigid block partition. After the two methods are introduced, some benchmark problems are analysed to illustrate the numerical performances of the two approaches and the “pro et contra” of these two opposed strategies. The effectiveness of the rigid block approach combined with energy minimization, is also tested on some benchmark problems, such as the problem of the arch subject to given settlements, the Couplet’s problem, and the determination of the collapse load multiplier of horizontal forces. A number of case studies concerning real masonry structures is also presented to illustrate the effectiveness of the proposed method.

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