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Despite the fact that in recent years Portugal has not seen the occurrence of high-magnitude earthquakes, it remains threatened by these events due to its geographic location. Since the 1960s, reinforced concrete has been the most used material for new constructions, however the historic urban centers are dominated by old unreinforced masonry (URM) buildings which techniques and construction materials have evolved since the Great Lisbon earthquake that occurred in 1755 with a magnitude around 8.5. Given the presence of these buildings in areas of significant seismicity, a comprehensive research is needed to assess the seismic risk and define mitigation policies. This kind of studies are often supported by empirical methods and based on expert judgment due to the high variability of the building stock and lack of information. The main purpose of this work is: i) to provide analytical fragility curves, supported by nonlinear static analysis, for the entire population of old masonry buildings, built before the introduction of the first design code for building safety against earthquakes (RSSCS) in 1958; ii) define vulnerability curves to be used by the technical community for seismic risk assessment of pre code URM buildings. The characterization of the building stock geometry and material properties is based on the previous information collected, which was useful to define representative archetypes and typologies.

Earthquakes are a major cause of damage and human losses to the built environment, including cultural heritages, monumental buildings and historical centers. In the last decades the seismic performance of buildings has received special attention due to the interest in the built heritage conservation and protection of human life, particularly with respect to masonry structures which have shown evidence of poor behavior once subjected to seismic loads. The present work contributes to the seismic safety assessment of the out-of-plane behavior of unreinforced masonry walls through a displacement-based approach, providing the capacity for different out-of-plane geometric indexes and its seismic response in different earthquake-prone regions. The analyses are conducted using a seismic probabilistic framework, considering the most common out-of-plane mechanisms, different material properties, various slenderness ratios, and a wide range of seismicity levels to cover the seismic hazard in Europe. The results presented can be useful for seismic safety assessment and to incorporate vulnerability models for seismic risk analysis.

Post-earthquake damage reports have continuously highlighted the significant vulnerability of nonstructural elements to seismic events. Nonstructural damage has severe impact in the building recovery, increasing the socioeconomic losses even for low intensity events. In the last few years, research efforts have focused on the development of innovative nonstructural solutions, to be combined with damage-resistant structural skeletons in order to obtain an overall highperformance building. As part of a European Union (EU)-funded project, the effectiveness of such integrated skeleton&envelope low-damage system in reducing the earthquake related losses was investigated. Tridimensional shake table tests on a 1:2 scaled timber-concrete low-damage structural skeleton, “dressed” by different innovative nonstructural elements (glass/concrete facades, gypsum/ masonry partitions), were performed at the National Laboratory for Civil Engineering (LNEC) in Lisbon, Portugal. The shake table testswere carried out at increasing seismic intensities to investigate the structural and nonstructural performance up to a higher-than Collapse Prevention Limit State according to the Italian Code (975 years return period). This paper focuses on the dynamic behavior of nonstructural elements with detailed discussion on construction detailing, seismic demand and performance of the innovative solutions. The high performance of nonstructural elements proved the potential of the details introduced in the partitions/facades. Minimal or no damage was observed up to the end of the overall testing sequence, which reached moderate-to-high interstory drift ratios (more than 1.00%) - typically expected to cause severe damage to traditional nonstructural partitions/infills/facades.

This paper describes a shake table test on a one-storey full-scale unreinforced masonry structure, which complements an earlier testing of a two-storey structure with similar characteristics. The building specimen was meant to represent the upper floors of the end-unit of a terraced house, built with cavity walls and without any particular seismic design or detailing. In these specimens, the masonry walls were composed of two leaves: a load-bearing inner one made of calcium silicate bricks sustaining a reinforced concrete floor and an external leaf made of clay-bricks connected to the inner leaf by means of metallic ties. A pitched timber roof was supported by two triangular gable walls. Floor acceleration response histories of the previously tested two-storey specimen were used as input motions. An incremental dynamic test, with vertical and horizontal inputs, was carried out up to the explicit collapse of some bearing elements of the structure. In particular, a two-way bending out-of-plane collapse of a load-bearing wall was observed and described.

After the large destruction of Lisbon due to the 1755 earthquake, the city had to be completely rebuilt. The innovative “Pombalino” buildings, named after the Prime Minister Marquis of Pombal, were then developed. This type of building is characterized by its structural interior “frontal” walls in elevated floors, composed of a timber frame with vertical and horizontal elements, braced with diagonals and masonry infill. The research presented in this paper aims at assessing the seismic behavior of the “Pombalino” buildings and proposes a strengthening technique by reinforcing the timber framed “frontal” walls. The experimental program was based on extensive dynamic testing on prototypes representative of typical “frontal” walls. The results of the dynamic tests carried out in the LNEC 3D shaking table are presented regarding the two types of tests performed: (a) seismic tests, in which the seismic action was applied with increasing amplitude in the in-plane direction; (b) dynamic identification tests, performed before the first and after each increasing amplitude seismic test, aiming at evaluating the evolution of the models’ mechanical properties with increasing seismic amplitude tests. A comparison of the performance of the non-strengthened and strengthened tested prototypes is also presented.

Masonry veneer walls have been used successfully in a wide variety of structures in modern building construction. However, their vulnerability under seismic actions is recognized as the result of poor material selection, design and construction practices. The knowledge of the local behaviour of ties under different loading conditions should provide important information to help in the selection of the most appropriate wall ties, improving seismic performance. An experimental campaign of different brick-tie-brick assemblages subjected to cyclic tension–compression loading is presented in this paper and the results (stiffness, strength, dissipation of energy and failure modes) are discussed in detail.

Lessons from recent earthquakes have provided a tough reality check of the current seismic design approach, highlighting a critical mismatch between societal expectations over the reality of seismic performance of modern buildings. The performance-based design criteria and objectives need a paradigm shift towards low-damage design philosophy and technologies that should The project provided the opportunity to coordinate a unique research effort for the development and possible future implementation in the European Environment of an integrated low-damage building systems, including structural skeleton and non-structural components for the next generation of buildings.embrace the entire building system. The final goal is the development of a cost-affordable high-performance building system, including structural skeleton, non-structural elements, services and soil foundation systems, capable of sustaining a design level earthquake with limited damage, controllable socio-economic losses and minimum disruption of business. The modern society is waiting for an “earthquake proof” and eco-friendly building at affordable costs. This paper provides an overview and the preliminary results of the EU-funded SERA project titled “(Towards the) Ultimate Earthquake proof Building System: development and testing of integrated low-damage technologies for structural and non-structural elements”. A damage-control building system based on post-tensioned rocking and dissipative mechanisms that combines self-centering and dissipating capabilities was “dressed” with traditional or lowdamage enclosures and fit-outs. A two-storey 1:2 scaled fully prefabricated and dry-assembled building with two bays timber-concrete low-damage seismic frames in one direction and post-tensioned rocking dissipative timber low-damage seismic walls in the other direction was designed and pre-assembled in Italy, then transported and tested on the 3D shaking table of the National Laboratory of Civil Engineering (LNEC) in Lisbon. The building also comprised two different flooring systems, namely a timber-concrete composite floor (TCC) at the first level and a prestressed timberconcrete floor (3PT) at the second level. Three test stages were performed: 1) the bare structural skeleton solution; 2) the structural skeleton including internal gypsum partitions and 3) the integrated skeleton + envelope system. Exterior GFRC panels in the frame direction and spider glazing systems in the wall direction with an internal low-damage clay brick infill wall were investigated during the last stage. Preliminary test results will be herein discussed After many cycles of input motions at different seismic intensities, the integrated low-damage system proved a very high seismic performance, confirming the unique potential of low-damage building system and the opportunity for their widespread implementation in the design and construction practice.

A avaliação da segurança sísmica de edifícios existentes tem como quadro de referência o Eurocódigo 8 – Parte 3 (NP EN 1998-3; 2017), que apresenta procedimentos de avaliação com âmbito de aplicação geral. A complexidade destes procedimentos, aliada ao reconhecimento de que uma parte significativa do território nacional apresenta uma sismicidade moderada a baixa, faz com que a aplicação dos procedimentos definidos neste código seja demasiado complexa para a maioria dos edifícios existentes de pequeno a médio porte, que cumpram certos requisitos de regularidade estrutural. Além disso, dada a natureza estocástica dos sismos, o nível de exigência da segurança estrutural a requerer para as diferentes tipologias de edifícios nas diferentes zonas sísmicas deve ser definido em termos probabilísticos de forma a garantir que a probabilidade de se excederem certos níveis de danos, devido à ocorrência de sismos, seja uniforme no território nacional. Neste contexto, foi desenvolvido um estudo realizado ao abrigo do Protocolo de Colaboração no âmbito do Estudo de Procedimentos para Certificação Sísmica de Edifícios Existentes, de 2014, de cooperação entre o Laboratório Nacional de Engenharia Civil (LNEC) e a Sociedade Portuguesa de Engenharia Sísmica (SPES) com o objetivo de definir procedimentos alternativos expeditos que, não pretendendo substituir a aplicação da regulamentação existente para a totalidade dos edifícios, permitem avaliar a segurança sísmica de uma sub-classe considerável de edifícios de forma mais expedita comparativamente aos procedimentos regulamentares de referência. Assim, neste documento são propostos dois métodos expeditos que permitem avaliar a resistência sísmica de edifícios de betão armado sem recurso a modelos numéricos, apenas com base nas propriedades geométricas (Método I) e também mecânicas (Método II) dos pilares dos edifícios. Não obstante a simplicidade dos dois métodos expeditos, utilizaram-se no seu desenvolvimento análises probabilísticas de avaliação de segurança sísmica (Nível 3, avaliação da probabilidade de excedência de estados limites), aplicadas a um universo de estruturas representativas de uma fração relevante do parque habitacional português. Os métodos aqui propostos permitem assegurar o mesmo nível de fiabilidade estrutural para diferentes graus de perigosidade sísmica em Portugal com avaliações tendencialmente mais conservativas para métodos com graus de simplificação crescente. Apresenta-se neste documento uma descrição detalhada das diferentes fases do estudo desenvolvido, terminando com um exemplo de aplicação dos diferentes métodos a um edifício existente de betão armado e com uma avaliação do grau de aproximação dos resultados obtidos com os métodos expeditos propostos relativamente à metodologia de avaliação sísmica de referência definida na NP EN1998-3 (2017). info:eu-repo/semantics/publishedVersion

A avaliação da segurança sísmica de edifícios existentes tem como quadro de referência o Eurocódigo 8 – Parte 3. Tendo em conta que uma parte significativa do território nacional apresenta uma sismicidade moderada a baixa, a aplicação dos procedimentos definidos neste código conduz a análises demasiado complexas para a maioria dos edifícios existentes de pequeno a médio porte. Neste trabalho são propostos dois métodos expeditos que permitem avaliar a resistência sísmica de edifícios de betão armado sem recurso a modelos numéricos, apenas com base nas propriedades geométricas (Método I) e também mecânicas (Método II) dos pilares dos edifícios. Não obstante a simplicidade destes métodos, utilizaram-se no seu desenvolvimento análises probabilísticas de avaliação de segurança sísmica, aplicadas a um universo de estruturas representativas de uma fração relevante do parque habitacional português. Os métodos aqui propostos permitem assegurar idêntico nível de fiabilidade estrutural para diferentes graus de perigosidade sísmica em Portugal, com avaliações mais conservativas para métodos com graus de simplificação crescente. info:eu-repo/semantics/publishedVersion

The analysis of the shaking table test of a 3-wall stone masonry structure performed with a discrete element model is presented. The numerical model, created with the code 3DEC, employed a rigid block representation and a Mohr-Coulomb joint model. Joint stiffness calibration to match the experimental natural frequencies is discussed, as well as the boundary conditions to simulate the shake table. Comparisons are made with the measured displacements at key locations, and the modes of deformation and fracture of the walls. The DEM model was able to reproduce important features of the shaking table tests. The experimental deformation and near collapse patterns were clearly identifiable in the numerical simulations, which produced displacements within the observed orders of magnitude, for the various levels of excitation.

Probabilistic seismic hazard for Mainland Portugal was re-evaluated in order to perform its disaggregation. Seismic hazard was disaggregated considering different spaces of random variables, namely, univariate conditional hazard distributions of M (magnitude), R (source-to-site distance) and e (deviation of ground motion to the median value predicted by an attenuation model), bivariate conditional hazard distributions of M–R and X–Y (seismic source latitude and longitude) or multivariate conditional hazard distributions of M–R–e and M–(X–Y)–e. The main objective of the present work was achieved, as it was possible, based on the modal values of the above mentioned distributions, to characterize the scenarios that dominate some seismic hazard levels of the 278 Mainland Portuguese counties. In addition, results of 4D disaggregation analysis, in M–(X–Y)–e, pointed out the existence of one geographic location shared by the dominant scenario of most analyzed counties, especially for hazard levels correspondent to high return periods. Those dominant scenarios are located offshore at a distance of approximately 70 km WSW of S. Vicente cape. On the other hand, the lower the return period the higher is the number of modal scenarios in the neighbourhood of the analyzed site. One may conclude that modal scenarios reproduce hazard target values in each site with great accuracy enabling the applications derived from those scenarios (e.g. loss evaluation) to be associated to a hazard level exceedance probability.

Most of the Lisbon 18th century timber-framed masonry “Pombalino” buildings currently need seismic rehabilitation due to: (i) natural degradation with aging; (ii) need for adaptation to new serviceability requirements, generally involving higher loads and consequent structural changes; (iii) former interventions with elimination or damage of structural elements, affecting seismic resistance and (iv) noncompliance with the present seismic codes. The research presented in this paper aimed at experimentally evaluating the seismic vulnerability of the “Pombalino” buildings and at proposing a strengthening technique to reduce it by reinforcing their timber framed “Frontal” walls. The experimental program was based on extensive dynamic testing on prototype representative of the current characteristic of “Frontal” walls. The results of the dynamic tests carried out in the LNEC 3D shaking table are presented regarding the two types of tests performed: (a) seismic tests, in which the seismic action was applied with increasing amplitude in the direction of the walls; (b) dynamic identification tests, aiming at evaluating the decrease of the mechanical properties of the models. A comparison of the performance of the non-strengthened and strengthened tested prototypes is also presented.

This paper describes a shaking-table experimental programme performed on four different multi-storey timber houses within the transnational Seismic Engineering Research Infrastructures for European Synergies (Series) project at the National Laboratory of Civil Engineering in Lisbon, Portugal. The aim of the Series project was to promote cooperation between main European research centres by giving access to their facilities. Under the timber buildings research programme within the Series framework, four real-scale three-storey buildings of plan dimension 7 × 5 m were assembled and tested: two timber-frame houses, one log house and one cross-glued laminated timber house. This paper describes the common parts of the various tests undertaken, such as the test set-up and the measurement layout. The tests themselves are described in a series of companion papers by the authors.

In the scope of the transnational access activities of the European research project SERIES, the Laboratorio Nacional de Engenharia Civil (LNEC) has provided access to its 3D shaking table to the international construction company Wienerberger AG and to a group of European experts, in order to perform full-scale seismic tests on an industrial solution for buildings using a modern unreinforced thermal insulation clay block masonry structure. Such solution represents a very common construction method in Central Europe and, although there are cyclic shear test results available, its effective dynamic response under seismic events still requires experimental validation. For this purpose, two full-scale mock-ups with different geometries were tested on the 3D shaking table using a series of seismic records with increasing intensity. This paper focuses on the most relevant experimental results regarding the structural response of the specimens, e.g., the dynamic response evolution, the collapse mechanism identified and the maximum drift values measured. The paper closes with the main conclusions drawn and with proposals for future developments.

Eurocode 8 imposes the use of reinforced solutions in order to ensure that the in-plane and out-of-plane damage of masonry infill walls due to seismic actions complies with given performance level requirements. Nevertheless, Eurocode 8 does not provide design rules or methodologies for the detailing of such reinforcement. An experimental programme was thus defined for assessing the response of innovative solutions for non-load bearing masonry enclosures using LNEC’s triaxial shake table. Two reinforcement solutions were tested on single leaf clay brick infill walls: (i) horizontal reinforcement in the bedding planes of the masonry units and (ii) reinforced mortar coating. Furthermore, a testing device for masonry infill panels was specifically conceived for this project. A detailed description of the methods used is given and the experimental results are partially presented and interpreted on the basis of the structural response and its evolution with damage.

SUMMARY The present work describes a shaking table experimental campaign specifically developed for the characterisation of the out-of-plane response of a full scale stone masonry facade. After the description of the specimen and the selection of the input motion presented in a companion paper (Part 1), the experimental campaign is illustrated and extensively described. The out-of-plane behaviour of the sacco masonry facade is presented in terms of displacements, velocities, and accelerations recorded during the shaking table tests. A one-sided rocking response of the facade was observed prior to collapse. The impacts were clearly identified in the acceleration records. The facade overturning occurred with the expected failure mode, as predicted in the design of the test. Finally, some conclusions are drawn regarding the observed behaviour and particular features of this type of stone masonry constructions, which may influence the global behaviour of the facade. Copyright © 2013 John Wiley & Sons, Ltd.

SUMMARY The out-of-plane response of walls in existing stone masonry buildings is one of the major causes of vulnerability commonly observed in post-earthquake damage surveys. In this context, a shaking table (ST) test campaign was carried out on a full-scale masonry facade mainly focusing on the characterization of its out-of-plane overturning behaviour. The structure tested on the ST is a partial reproduction of an existing building from Azores, damaged during the 9 July 1998 Faial earthquake. The definition of the tested specimen as well as the selection of the input ground motion is reported in this paper. A specific emphasis is given to the definition of the time-history to be applied during the tests because it was felt as an essential and crucial part of the work to obtain the desired overturning behaviour. The accelerogram to be imposed was selected from a large set of accelerograms (74) by means of a step-by-step procedure on the basis of several numerical analyses resorting to the rocking response of rigid blocks. A companion paper (Part 2) focuses on the ST test results and detailed data interpretation. Copyright © 2013 John Wiley & Sons, Ltd.

Masonry buildings worldwide exhibited severe damage and collapse in recent strong earthquake events. It is known that their brittle behavior, which is mainly due to the combination of lowtensile strength, largemass and insufficient connection between structural elements, is the main limitation for their structural implementation in residential buildings. A new construction system for masonry buildings using concrete blocks units and trussed reinforcement is presented here and its seismic behavior is validated through shaking table tests. Dynamic tests of two geometrically identical two-story reduced scale (1:2) models have been carried out, considering artificial accelerograms compatible with the elastic response spectrum defined by the Eurocode 8. The first model was reinforced with the new proposed system while the second modelwas built with unreinforced masonry. The experimental analysis encompasses local and global parameters such as cracking patterns, failure mechanisms, and in-plane and out-of-plane behavior in terms of displacements and lateral drifts from where the global dynamic behavior of the two buildings is analyzed comparatively. Finally, behavior factors for the design recommendations in case of unreinforced masonry are alsoevaluated., QREN (POFC) - ADI - Agência de Inovação

The out-of-plane response of walls in existing stone masonry buildings is one of the major causes of vulnerability commonly observed in post-earthquake damage surveys. In this context, a shaking table (ST) test campaign was carried out on a full-scale masonry facade mainly focusing on the characterization of its out-of-plane overturning behaviour. The structure tested on the ST is a partial reproduction of an existing building from Azores, damaged during the 9 July 1998 Faial earthquake. The definition of the tested specimen as well as the selection of the input ground motion is reported in this paper. A specific emphasis is given to the definition of the time-history to be applied during the tests because it was felt as an essential and crucial part of the work to obtain the desired overturning behaviour. The accelerogram to be imposed was selected from a large set of accelerograms (74) by means of a step-by-step procedure on the basis of several numerical analyses resorting to the rocking response of rigid blocks. A companion paper (Part 2) focuses on the ST test results and detailed data interpretation. Copyright (c) 2013 John Wiley & Sons, Ltd.

Nesta comunicação descreve-se o trabalho desenvolvido no estudo do comportamento sísmico da Igreja do Mosteiro da Serra do Pilar. A partir da modelação numérica tridimensional da igreja e da quantificação de parâmetros mecânicos e dinâmicos da estrutura, a análise sísmica foi realizada em duas fases de cálculo. Procedeu-se a um primeiro cálculo linear global da estrutura, seguido de um segundo cálculo da subestrutura dos arcos e colunas de apoio onde foi activado o comportamento não-linear das juntas entre blocos e analisado o efeito resultante da aplicação de intensidades sísmicas crescentes.