Simulation of the Out-of-Plane Behaviour of URM Walls by Means of Discrete Macro-Element Method

The seismic response of masonry structures without box-type behaviour is given by a complex interaction between in-plane and out-of-plane behaviours. Previous earthquakes demonstrated that out-of-plane failure mechanisms represent the main cause of structural collapses of UnReinforced Masonry (URM) and historical structures. Previous experimental and analytical studies, investigating the out-of-plane behaviour of URM structures, mostly considered the effects of one-way bending moment. In this regard, recent experimental campaigns and numerical simulations have been conducted in order to investigate the out-ofplane behaviour of masonry walls subjected to two-way bending. These investigations have demonstrated the complexity of this mechanism and stressed the need for accurate numerical tools capable of providing reliable predictions in terms of ultimate strength and failure mechanisms. This paper focuses on the assessment of the dynamic behaviour of a U-shape URM prototype, subjected to shaking table tests, by means of a simplified computational strategy denoted as Discrete Macro-Element Method (DMEM). In this investigation, a comparison between experimental and numerical results was conducted in order to validate the capabilities of the proposed modelling approach. Subsequently, a parametric analysis was carried aiming at determining the influence that masonry mechanical properties, and additional model parameters, have on the out-of-plane nonlinear dynamic response of URM masonry structures

In-plane Behaviour of an Iron-Framed Masonry Façade: Comparison between Different Modelling Strategies

The ‘baraccato’ system is a construction technique with genius earthquake resilient features, used for the reconstruction of the historical city centres in the South of Italy after the catastrophic events occurred in the 18th-19th centuries. A very interesting example of such a building typology is represented by the Church of Santa Maria Maddalena, located in the municipality of Casamicciola Terme of the Ischia Island and built in 1896, after the catastrophic earthquake of 1883. The church is characterized by a mixed ‘baraccato’ system mainly made of yellow tuff block masonry walls strengthened by iron profiles or wooden elements. The reduced damage suffered by the church after the seismic event of 21st August 2017 evidenced the good behaviour of such a mixed structural system, especially into avoiding out-of-plane mechanisms. The presence of the iron-framed system is even more challenging in the definition of the modelling strategies for the structural analysis of the church. Thus, the choice of an appropriate numerical strategy to be used for nonlinear simulation should be properly investigated since the interaction between the frame elements and the elements representing the masonry walls has to be considered. As a first step of the structural analysis of the whole church, the in-plane behaviour of the main façade of the Church of Santa Maria Maddalena is analysed in this paper, with the aim to evaluate the efficacy of different modelling strategies. In particular, the study considers different models according to Finite and Discrete Element strategies available within DIANA FEA [1] and 3DMacro [2] software, respectively. Non-linear static analyses are carried out by means of both software and the obtained results are compared and discussed with the aim of extending them to the study of the whole church

Constructive Analysis and Modelling of a Single Nave Church: a Proposal for S. Sebastiano (EN, Italy)

The seismic events occurred in Italy in the last decay (L’Aquila 2009, Emilia 2012, Central Italy Earthquakes 2016/2017) have caused the collapse of numerous historical buildings and monuments with loss of life and irreversible damages to the cultural heritage. An effective seismic prevention would avoid, or delay, the most frequent collapse mechanisms. However, it requires a correct interpretation of the structural mechanical behavior. With regard to the traditional masonry buildings, this issue presents a high level of complexity due to the uncertainties related to the materials and the constructive techniques. Furthermore, historic buildings are often the result of several modifications that induce significant structural irregularities. A possible analysis strategy is provided by a discrete macro-element modelling (DMEM) approach which is able to simulate the global behavior of traditional fabrics, if supported by an adequate level of historic, geometrical, constructive and structural knowledge. In this paper a multidisciplinary procedure is applied to the church of S. Sebastiano in Regalbuto (Italy), considered as case study. This procedure is composed of three steps: the knowledge phase in which the constructive apparatus and the static schemes are identified, the modelling phase and the assessment phase in which the current safety level of the building and possible interventions that would be compatible with its cultural instance, are individuated. According to the followed procedure, different scenarios of intervention, characterized by increasing levels of benefit and invasiveness, are considered. For each scenario, non-linear static push-over analyses are performed, to evaluate the benefits and identify the structural critical issues, useful to individuate the next scenario. The obtained results are presented and discussed both in terms of capacity curves and failure mechanisms

A macro-modelling continuum approach with embedded discontinuities for the assessment of masonry arch bridges under earthquake loading

The paper presents a novel effective macro-modelling approach for masonry arches and bridges under cyclic loading, including dynamic actions induced by earthquakes. It utilises an anisotropic material model with embedded discontinuities to represent masonry nonlinearities. Realistic numerical simulations of masonry arch bridges under static and dynamic loading require accurate models representing the anisotropic nature of masonry and material nonlinearity due to opening and closure of tensile cracks and shear sliding along mortar joints. The proposed 3D modelling approach allows for masonry bond via simple calibration, and enables the representation of tensile cracking, crushing and shear damage in the brickwork. A two-scale representation is adopted, where 3D continuum elements at the structural scale are linked to embedded nonlinear interfaces representing the meso-structure of the material. The potential and accuracy of the proposed approach are shown in numerical examples and comparisons against physical experiments on masonry arches and bridges under cyclic static and dynamic loading

Discrete modelling of externally bonded composite layers on masonry structures

The safeguard of existing masonry structures requires the adoption of structural retrofitting strategies able to preserve the architectural of the construction. Numerous strengthening techniques are available for the rehabilitation of exitsting structures, including historic and monumental buildings, most of them based on the application of Externally Bonded Composite (EBC) layers on the masonry surfaces. Such a technique represents a low-invasive retrofitting strategy widely used in engineering practice. In this paper, within the framework of the Discrete Macro-Element Method (DMEM) already introduced by the authors, an original macro-element for modelling the interaction between masonry elements and EBC layers is presented. The proposed model is able to provide a reliable simulation of the EBC layer applications to masonry structures although maintaining a low computational burden. After a theoretical description of the EBC macro-element, the new macro-modelling approach is validated against experimental and numerical tests available in the literature

An Interdisciplinary Approach for the Geometric, Constructive, and Structural Assessment of Historical Masonry Domes with Application to the ‘Badia di Sant’Agata’ in Catania, Sicily

Masonry domes have always represented one of the most fascinating and daring architectural structures, with great symbolic relevance. However, their structural behaviour under environmental actions, such as earthquakes, has not yet been thoroughly investigated. This paper defines an interdisciplinary methodological approach, based on advanced digital survey techniques to evaluate constructive, geometrical, and structural aspects of historical domes. The applied procedure comprises the study of archival documents and diagnostic reports, in-situ analyses and advanced three-dimensional surveys, the development of simplified discrete-element-based structural models, and the performing of pushover analyses. The procedure is applied to a case study represented by the dome of the ‘Badia di Sant’Agata’ church in Catania, an earthquake-prone town located in Eastern Sicily. This church was built after the devastating 1693 earthquake and its dome represents one of the most significant examples among hundreds of masonry domes built in Sicily. The historical and constructive investigation showed that the dome was built without supporting formworks, by laying 21 concentric courses of limestone voussoirs on a peculiar springing ring made of mortared rubble stones. The numerical simulations highlighted that this peculiar ring affects the dome’s failure mechanism and limits its displacement capacity and the maximum shear transferred to the substructure

Modelling of the out-of-plane behaviour of unreinforced masonry panels using the Discrete Macro-Element Method (DMEM)

Existing unreinforced masonry (URM) buildings, including historical and monumental structures, represent an important architectural and cultural heritage for several countries worldwide. The response of URM, subjected to earthquake excitations, is strongly governed by the out-of-plane (OOP) response of masonry walls, which can lead to local failure mechanisms, even at low levels of seismic loading. The OOP failure conditions are mainly controlled by the geometry of the structure and the masonry quality. Different strategies are used for modelling the OOP response of URM structures including limit analysis and nonlinear FEM. A further recently proposed strategy is based on the discrete macro-element method (DMEM) which allows the simulation of the in-plane and the OOP response of masonry walls with a reduced computational cost compared to the other numerical strategies. In this paper, the DMEM is applied to simulate a masonry wall rocking experimental campaign for which other numerical strategies have already been applied. The dissipation effects, related to the rocking motion and the repetitive impacts, are taken into account according to an equivalent viscous damping approach. Furthermore, the role of masonry deformability is investigated by comparing the results obtained by the DMEM model, for different value of masonry elastic modulus, with those obtained by typical rigid-block based models. The results clearly demonstrate that the DMEM can be efficiently adopted to accurately predict the dynamic response of monumental structures.- (undefined

FRP-reinforced masonry structures: Numerical modeling by means of a new discrete element approach

The protection of existing historical masonry structures represents a relevant topic in view of the high social and economic values of such constructions. Many strengthening techniques for the rehabilitation of existing monumental structures have been introduced. Some of these strategies are based on the application of fiber reinforced composite materials on the masonry surface. Among these, the application of FRP (Fiber Reinforced Polymers) is a low invasive retrofitting strategy able to improve both the in-plane and the out of plane masonry behaviour applicable to many different structural geometrical layouts. In this paper, by taking advantage of a parsimonious discrete element approach already introduced by the authors, a new strip macro-element for the interaction modeling between masonry elements and FRP reinforcement is proposed. This new element is able to provide a satisfactory simulation of the FRP layer applications toin masonry structures although maintaining a very low computational effort. In the paper, after a theoretical description of the proposed strategy, some numerical applications on case-studies, already investigated in the literature, highlight the capability of the proposed approach to properly describe the collapse behaviour of FRP reinforced masonry structures.(undefined)info:eu-repo/semantics/publishedVersio

Un approccio innovativo per la modellazione degli edifici in muratura intelaiata. Applicazione ad un caso di studio

Le strutture in muratura intelaiata rappresentano una parte rilevante delle strutture esistenti e sono ancora largamente adottate come sistema strutturale per la costruzione di edifici residenziali, soprattutto in aree del mondo a forte sismicità non fortemente industrializzate e nelle quali la muratura rappresenta ancora un materiale tradizionale e a basso costo. In questo lavoro viene presentato un approccio per macro-elementi per la valutazione della risposta sismica di strutture in muratura confinata. La complessa interazione tra il telaio e la muratura è simulata mediante un approccio originale in cui il telaio è modellato con aste a plasticità concentrata mentre il contributo della muratura è descritto per mezzo di un macro-elemento piano, originariamente introdotto per lo studio degli edifici in muratura non rinforzata. La strategia computazionale proposta è concepita per fornire uno strumento di calcolo efficace che, a fronte di un costo computazionale relativamente basso, sia utilizzabile per il progetto e la valutazione della vulnerabilità di strutture in muratura confinata sia in ambito accademico che professionale