Numerical approaches for the analysis of timber frame walls

A numerical approach to simulate the behaviour of timber shear walls under both static and dynamic loading is proposed. Because the behaviour of timber shear walls hinges on the behaviour of the nail connections, the force-displacement behaviour of sheathing-to-framing nail connections are first determined and then used to define the hysteretic properties of finite elements representing these connections. The model nails are subsequently implemented into model walls. The model walls are verified using experimental results for both monotonic and cyclic loading. It is demonstrated that the complex hysteretic behaviour of timber shear walls can be reasonably represented using model shear walls in which nonlinear material failure is concentrated only at the sheathing-to-framing nail connections

Applicability of FEM for nonlinear seismic analysis of URM structures with timber diaphragms accounting for wall-to-floor/roof connections

The seismic behaviour of unreinforced masonry (URM) structures is generally governed by a complex interaction between the out-of-plane and in-plane responses of the walls, depending on the in-plane stiffness of timber diaphragms and the efficiency of wall-to-floor/roof connections. The presence of timber diaphragms, which are typically characterized by low in-plane stiffness and poor connection to the masonry walls, adds hindrances to the numerical modelling and analysis as well as to the structural assessment of URM structures under seismic actions. This work aims at developing a numerical study to investigate the seismic behaviour of URM buildings with timber diaphragms accounting for wall-to-floor/roof connections. The reference model used in this study is a full-scale two-storey prototype building which was subjected to shaking table tests at the European Centre for Training and Research in Earthquake Engineering (EUCENTRE), in Italy. Refined finite element (FE) models have been developed in DIANA software under different modelling assumptions for the timber diaphragms and their connections to the masonry walls. Eigenvalue, nonlinear static and nonlinear dynamic analyses have been carried out to calibrate and validate the models with respect to the experimental data. The results are discussed in terms of: (1) suitable modelling assumptions for the vertical structure and timber diaphragms; (2) derivation of mechanical properties for the timber diaphragms from available experimental data; (3) accuracy in predicting the experimental behaviour of the prototype building when refined FE modelling is used; and (4) advantages and limitations of applying nonlinear static and dynamic analyses

Experimental investigation of the behaviour of injection anchors in rubble stone masonry

The seismic response of historical masonry buildings is largely controlled by the effectiveness of wall-to-diaphragm connections, which can be improved using injection anchors. Despite their use, there is a need for a better understanding of the performance of such anchoring system in stone masonry walls. This paper presents quasi-static pull-out tests performed on twelve specimens to investigate the behaviour of injection anchors in rubble stone masonry walls when breakout failure occurs. For each specimen, the experimental results are presented in terms of force–displacement curves, propagation of damage and crack pattern. It is shown that the anchoring details adopted in this study had a negligible influence on the pull-out force capacity of the anchoring system, while an increase in peak pull-out force was observed with increasing overburden stress applied. Because stone masonry specific capacity formulations have not yet been presented in the literature, the capacity is predicted using state-of-the art formulations for the pull-out load capacity of anchors installed in brick masonry. The limits of their applicability are discussed using the obtained experimental results.FCT -Fundação para a Ciência e a Tecnologia(PD/BD/127910/2016

Engineering simulations of a super-complex cultural heritage building: Ica Cathedral in Peru

The Cathedral of Ica, Peru, is one of the four prototype buildings involved in the ongoing Seismic Retrofitting Project, initiative of the Getty Conservation Institute. The complex historical building, which was heavily damaged by earthquakes in 2007 and 2009, can be divided into two substructures: an external masonry envelope and an internal timber frame built by a construction method known as quincha technique. This study makes use of the information available in literature and the results obtained from experimental campaigns performed by Pontificia Universidad Catlica del PerA and University of Minho. Nonlinear behaviour of masonry is simulated in the numerical models by considering specified compressive and tensile softening behaviour, while isotropic homogeneous and linear behaviour is adopted for modelling timber with appropriate assumptions on the connections. A single representative bay was initially studied by performing linear elastic analysis and verifying the compliance with the various criteria specified by the applicable normative to discuss the actual failure of Ica Cathedral. Afterwards, the structural behaviour of the two substructures composing the Cathedral is evaluated independently. Finally, the interaction of these two substructures is investigated by performing structural analysis on the entire structure of Ica Cathedral. Several structural analysis techniques, including eigenvalue, nonlinear static and dynamic analyses, are performed in order to: (1) evaluate the dominant mode shapes of the structure; (2) validate the numerical models by reproducing the structural damage observed in situ; (3) estimate the structural performance; and (4) identify the main failure mechanisms.This work was carried out with funding from the Getty Seismic Retrofitting Project under the auspices of the Getty Conservation Institute (GCI). This work is also partially financed by FEDER funds through the Competitivity Factors Operational Programme-COMPETE and by national funds through FCT-Foundation for Science and Technology within the scope of the projects POCI-01-0145-FEDER-007633 and PTDC/ECM-EST/2777/2014.info:eu-repo/semantics/publishedVersio

Shake‑table testing of a stone masonry building aggregate: overview of blind prediction study

City centres of Europe are often composed of unreinforced masonry structural aggregates, whose seismic response is challenging to predict. To advance the state of the art on the seismic response of these aggregates, the Adjacent Interacting Masonry Structures (AIMS) subproject from Horizon 2020 project Seismology and Earthquake Engineering Research Infrastructure Alliance for Europe (SERA) provides shake-table test data of a two-unit, double-leaf stone masonry aggregate subjected to two horizontal components of dynamic excitation. A blind prediction was organized with participants from academia and industry to test modelling approaches and assumptions and to learn about the extent of uncertainty in modelling for such masonry aggregates. The participants were provided with the full set of material and geometrical data, construction details and original seismic input and asked to predict prior to the test the expected seismic response in terms of damage mechanisms, base-shear forces, and roof displacements. The modelling approaches used differ significantly in the level of detail and the modelling assumptions. This paper provides an overview of the adopted modelling approaches and their subsequent predictions. It further discusses the range of assumptions made when modelling masonry walls, floors and connections, and aims at discovering how the common solutions regarding modelling masonry in general, and masonry aggregates in particular, affect the results. The results are evaluated both in terms of damage mechanisms, base shear forces, displacements and interface openings in both directions, and then compared with the experimental results. The modelling approaches featuring Discrete Element Method (DEM) led to the best predictions in terms of displacements, while a submission using rigid block limit analysis led to the best prediction in terms of damage mechanisms. Large coefficients of variation of predicted displacements and general underestimation of displacements in comparison with experimental results, except for DEM models, highlight the need for further consensus building on suitable modelling assumptions for such masonry aggregates

Análise estrutural das estruturas de madeira abobadados na Catedral de Ica

Dissertação de mestrado em Structural Analysis of Monuments and Historical ConstructionsThe Cathedral of Ica, built in 1759 and damaged by the 2007 Pisco earthquake, is one of the most representative of the churches built in coastal cities of Peru. Declared as national monument in 1982, Ica Cathedral is part of the Seismic Retrofitting Project of the Getty Conservation Institute. Two structural systems are present in Ica Cathedral. At the exterior, a massive and stable load– bearing masonry envelope surrounds the cathedral consisting of the fired brick front façade with two bell towers and thick mud brick lateral walls. On the other hand, the internal space of Ica Cathedral is divided by a series of pillars that support a complex vaulted roof framing system constructed with the quincha technique. In particular, the latter is the main object of this thesis. The important influence of timber connections on the global behaviour of timber structures is investigated by modelling a timber frame wall, analytically and numerically. The architecture, the structural systems and recent damage of Ica Cathedral are presented in details with the construction of 3D–architectural models in AutoCAD. Performing linear elastic analyses on the model of the representative bay in SAP 2000 software, the compliance with the criteria specified by Eurocode is evaluated. Finally, the elastic behaviour of the complete timber structure is investigated by constructing a model in MIDAS FX+ for DIANA software. The results obtained from this thesis represent a starting point for the further research on the numerical model of the combined timber and masonry structures of Ica Cathedral.A Catedral de Ica, construída em 1759 e danificada pelo terremoto de Pisco em 2007, é uma das mais representativas igrejas construídas nas cidades costeiras do Peru. Declarada como monumento nacional em 1982, a Catedral de Ica é parte do projeto Seismic Retrofitting Project do Getty Conservation Institute. Dois sistemas estruturais estão presentes na Catedral de Ica. No exterior, uma massiva e estável alvenaria estrutural envolve a catedral, consistindo numa fachada frontal em tijolo com duas torres e as paredes laterais de elevada espessura compostas por alvenaria de adobe. Por outro lado, o espaço interno da catedral é dividido por uma série de pilares que suportam a estrutura da cobertura que é composta por um complexo sistema abobadado construído com a técnica de quincha. Em particular, este último é o principal objeto desta tese. A importante influência das ligações de madeira no comportamento global das estruturas de madeira é investigada através da modelação de uma parede de estrutura de madeira, analiticamente e numericamente. A arquitetura, os sistemas estruturais e os danos recentes observados na catedral são apresentados em detalhe com modelos arquitetónicos 3D executados em AutoCAD. Foram realizadas análises elásticas lineares de um modelo representativo da estrutura através do software SAP 2000, avaliando a conformidade com os critérios especificados pelo Eurocode. Finalmente, o comportamento elástico de toda a estrutura de madeira é investigado através da construção de um modelo em MIDAS +FX para o software Diana. Os resultados obtidos com esta tese representam um ponto de partida de um modelo combinado de madeira e alvenaria para a Catedral de Ica

Applicability of FEM and pushover analysis to simulate the shaking-table response of a masonry building model with timber diaphragms

The seismic behaviour of unreinforced masonry (URM) structures is generally governed by a complex interaction between the out-of-plane and in-plane responses of the walls, depending on the in-plane stiffness of floor/roof diaphragms and the efficiency of wall-to-floor/roof connections. The presence of timber diaphragms, which are typically characterised by low in-plane stiffness and poor connection to the masonry walls, adds challenges to the numerical modelling and analysis, as well as to the structural assessment of URM structures under seismic actions. This work aims at investigating the applicability of refined FE modelling using macro-modelling approach and mass-proportional pushover analysis for simulating the response of URM structures with flexible diaphragms, comparing the results with experimental data obtained from incremental dynamic testing. A full-scale two-storey prototype building with timber diaphragms, which was tested in shaking table at the European Centre for Training and Research in Earthquake Engineering (EUCENTRE), in Italy, was considered to perform this study. A refined finite element (FE) model was developed in DIANA software, considering the wall-to-diaphragm (WTD) connections. While the strength values of masonry were adopted according to axial and diagonal compression tests, the modulus of elasticity was calibrated after simulating in-plane cyclic shear tests of masonry piers, which were part of the same experimental program at EUCENTRE. Recommendations from international guidelines were used to derive the assumed material properties for diaphragms and wall-to-diaphragm connections. Mass-proportional pushover analysis was performed and a comparison between numerical and experimental results is presented to investigate the assumptions, advantages and limitations of the presented numerical modelling and analysis approach

CALIBRATION OF A FEM MODEL WITH COMPLEX GEOMETRY: THE CASE STUDY OF SANTA MARIA MADDALENA CHURCH IN ISCHIA, ITALY

The technology of the Bourbonic casa Baraccata is one of the earliest earthquake resisting systems, used since the 18th century across Southern Italy in response to the disastrous earthquakes that hit the region frequently. The church of Santa Maria Maddalena in Casamicciola Terme, Ischia Island, Italy, represents one of the very rare examples, with a unicity lying on the combination of materials adopted. It presents the regular Bourbonic Baraccato walls in the back portion, and tuff-masonry walls embraced in iron frames in the main body. The paper aims at presenting the development of a 3D Finite Element Model (FEM) calibrated taking advantage of ambient vibration tests performed under operational conditions. Sensitivity analyses allowed to inspect and validate several modeling strategies and explore the relevance of the data still unknown to define a reliable numerical model to perform the study on the seismic behavior of the church of Santa Maria Maddalena

Calibration of a FEM model with complex geometry: The case study of Santa Maria Maddalena church in Ischia, Italy

The technology of the Bourbonic casa Baraccata is one of the earliest earthquake resisting systems, used since the 18th century across Southern Italy in response to the disastrous earthquakes that hit the region frequently. The church of Santa Maria Maddalena in Casamicciola Terme, Ischia Island, Italy, represents one of the very rare examples, with a unicity lying on the combination of materials adopted. It presents the regular Bourbonic Baraccato walls in the back portion, and tuff-masonry walls embraced in iron frames in the main body. The paper aims at presenting the development of a 3D Finite Element Model (FEM) calibrated taking advantage of ambient vibration tests performed under operational conditions. Sensitivity analyses allowed to inspect and validate several modeling strategies and explore the relevance of the data still unknown to define a reliable numerical model to perform the study on the seismic behavior of the church of Santa Maria Maddalena.- This work was carried out in the frame of the Advanced Master in Structural Analysis of Historical Constructions and Monuments (SAHC) and partially sponsored by the Italian Civil Protection, through the RELUIS Project - WP4: MAppe di Rischio e Scenari di danno sismico (MARS) (2020). The mentioned in-situ analyses were performed under the commission of the Campania Regional Directorate for Cultural Heritage (MiBACT)

Seismic behaviour of a mixed iron-masonry church: Santa Maria Maddalena, Ischia

The concept of vulnerability of the existing building stock is receiving increasing awareness and central importance in the scientific community working in earthquake risk mitigation. This assumes even more relevance when dealing with heritage structures located in relevant seismic hazard zones. This paper aims to identify and describe the earthquake-resistant features found in a unique masonry church in Ischia (Italy), and discuss their effectiveness on the impact of the post-seismic damage through the application of non-linear static analyses. The Santa Maria Maddalena Church represents one of the rare examples in which the technology of the Borbonic casa Baraccata (mixed timber-masonry construction), already well-known in the literature for its use in Italian seismic areas since the eighteenth century, is applied with the non-conventional combination of masonry and iron frames. The church was struck by the recent earthquake of 21 August 2017 with epicentre in Casamicciola Terme. The recorded post-seismic damage of the church evidenced non-relevant structural crack patterns, which are likely to be related to the efficacy of the construction system adopted.- (undefined