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Probabilistic risk assessment of RC building structures with masonry infills

Hugo Rodrigues; Humberto Varum; Aníbal Costa; Xavier Romão; António Arêde; Raimundo Delgado
Fonte: Universidade do Porto Publicador: Universidade do Porto
Tipo: Artigo de Revista Científica
POR
Relevância na Pesquisa
47.49%
The study of the seismic vulnerability of existent buildings in urban areas with moderated/high seismic risk is of extreme importance. Earthquake engineering experts, public authorities and general public alike agree on the idea that the assessment of the seismic safety and performance of the built environment is a matter of high priority.The proposed paper aims to carry out a structural fragility study where a representative RC building structure is modelled considering different characteristics (without masonry infills, with masonry infills and considering different mechanical characteristics of the infills). As the definition of fragility curves for the different analysis cases is the main objective of the study, the general outcome of the study will enable to assess the global importance of the referred material and mechanical uncertainties in the final fragility values and, therefore, in the potential mitigation measures that will be based on such results.

Validation of a simplified model for the design of masonry infilled frames

Lourenço, Paulo B.; Alvarenga, Rita de Cássia S. S.; Silva, Roberto Márcio da
Fonte: British Masonry Society (BMS) Publicador: British Masonry Society (BMS)
Tipo: Artigo de Revista Científica
Publicado em //2006 ENG
Relevância na Pesquisa
67.37%
The design of masonry infills is an issue that has attracted the attention of several researchers in the past, both from the experimental and analytical points of view. Nevertheless, the results are often questionable due to the large variability of masonry properties, the limited number of tests carried out and the large number of influencing factors. This paper addresses this limitation by using numerical analysis as a simulation of an experimental laboratory, and by performing a sensitivity analysis about the influence of the different influence factors. The modelling approach has been validated using the experimental results of two masonry walls subjected to horizontal loading. The parametric study subsequently carried out allowed to propose a strut-and-tie model that provides a novel simplified expression for the failure of infill walls belonging to frames subjected to horizontal loading. The proposed model is compared with other models available in the literature exhibiting superior performance and constituting a simple and versatile tool for design.; CAPES.; UFV.

Infill masonry : seismic behavior of reinforced solutions

Leite, João C.; Pereira, Manuel Fernando Paulo; Lourenço, Paulo B.
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em //2011 ENG
Relevância na Pesquisa
36.87%
The analysis of buildings constructed in the last 20 years, designed following modern standards, may lead to worrying conclusions. Images of out-of-plane expulsions and in-plane failures of infill walls in recent seismic activities around the world reminded engineers of the consequences of bad practice, wrong solutions or inadequate design. With the above in mind, a research program is being conducted as a partnership between University of Minho and the National Laboratory for Civil Engineering (LNEC), which includes a shaking table experimental program of framed concrete buildings with masonry infill walls, reinforced and unreinforced. Herein the shaking table program and the tested solutions are detailed, along with the discussion of the results, focusing on the local behaviour of the infills and the global behaviour of the concrete structure.

Masonry infills and earthquakes

Lourenço, Paulo B.; Leite, João C.; Pereira, Manuel Fernando Paulo
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em //2009 ENG
Relevância na Pesquisa
67.69%
Masonry infills are building elements with high cost that often suffer cracking due to movement of the supports and thermohygral behaviour, with serious consequences in comfort and efficiency, particularly in the case of enclosure walls. The new seismic code in Europe (Eurocode 8) clearly defines the structural designer as responsible for the safety of masonry infills. In this context, there is a clear need of adequate provisions to reduce the seismic vulnerability in regions of moderate and high seismicity, which are not clearly prescribed in the code. A research program involving monotonic and shaking table testing of masonry infills is being prepared at University of Minho and National Laboratory of Civil Engineering. The reasons for the program and a preliminary analysis of the prototype are addressed here.

On the influence of masonry infills in concrete buildings

Leite, João C.; Lourenço, Paulo B.
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em //2010 ENG
Relevância na Pesquisa
37.02%
The stresses induced in a structure by a seismic action have a low probability of occurrence and their magnitude is such that the structure is forced beyond the ultimate limit state. The effective standards in Portugal, and the ones that will be effective shortly, consider the possibility of a seismic action in all the territory, fact that has been neglect by designers and authorities in the last years. This new standard, Eurocode 8, Design of structures for earthquake resistance, defines new standards for infill walls, imposing the use of reinforcement but failing to give detailed information besides the type of reinforcement. Furthermore, the structural designer is the responsible for these non-structural elements. Therefore, with the goal of contributing to the creation of simple design rules for these infills, a shaking table test program of reinforced concrete frame buildings with infill walls, reinforced and unreinforced, will be carried out. Predeceasing these tests, different numerical simulations of the buildings were carried out, with two main objectives: i) understand the behavior of the structure when subjected to a seismic action, in order to more accurately define the experimental program; ii) using different computational programs and numerical elements to perform static non-linear analyses...

A brief overview on the retrofitting possibilities of masonry infill walls

Fangueiro, Raúl; Cunha, Fernando Eduardo Macedo; Vasconcelos, Graça; Abreu, S.
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em /11/2011 ENG
Relevância na Pesquisa
47.37%
This work presents a brief review on the seismic behavior on non-loadbearing masonry walls used as masonry infills. O Some examples of inefficient performance are shown based on information available of recent earthquakes. Additionally, a literature overview on the techniques for retrofitting existing masonry infills is provided. Finally, alternative braided reinforced composite materials are briefly described and pointed out as an alternative solution for retrofitting masonry infill walls.

Innovative retrofitting materials for brick masonry infill walls

Mora Gómez, Juan
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Dissertação de Mestrado
Publicado em //2012 ENG
Relevância na Pesquisa
37.54%
Dissertação de mestrado em Structural Analysis of Monuments and Historical Constructions; Last seismic events in Southern Europe have highlighted the vulnerability in the most usual constructive typology in contemporary architecture: framed structures with masonry infills. Contemporary structures have a good capacity to withstand these actions, given that they were considered for their design according to modern codes. Nonetheless, nonstructural elements as masonry infills show a high degree of damage even for medium magnitude earthquakes, causing casualties and high economic losses. For decades, these elements have been considered as nonstructural and therefore they were not requested to have resisting conditions. Given this, there is a large segment within the building stock in seismic prone areas that needs to undergo preventive action, specially for out-of-plane loads. This can range from a mere union of the infills to the frame structures to a reinforce of the elements, which can also be applied to the case of already damaged elements. The potential benefits go beyond the mere stability of nonstructural elements, as this would improve the behaviour of the whole structure to face seismic events. Some new fibre-based materials for structural reinforcement based in braiding techniques have been developed in the last years in the Universidade do Minho...

Solutions for infilled masonry buildings : shaking table tests

Leite, João C.; Lourenço, Paulo B.
Fonte: Universidade Federal de Santa Catarina (UFSC) Publicador: Universidade Federal de Santa Catarina (UFSC)
Tipo: Conferência ou Objeto de Conferência
Publicado em //2012 ENG
Relevância na Pesquisa
26.87%
Infilled masonry can be seen as an old research issue, but recent seismic activities, such as the 2009 Aquila earthquake in Italy, showed seismic engineers and structural designers that current infill solutions may not work as expected. In this seismic action, the analysis of the damages in buildings constructed in the last 20 years, designed according to modern standards, may lead to the worrying conclusion that the design Limit States were not fulfilled. Taking this into account, a research program was conducted as a partnership between the University of Minho, Portugal, and the National Laboratory for Civil Engineering (L.N.E.C.), Portugal, which included a shaking table experimental program. The objective of this program was to study the seismic behaviour of the most common infill solution in Portugal, the unreinforced double leaf clay brick masonry, and two reinforced solutions referenced in the standard Eurocode 8: i) single leaf clay brick with bed joint reinforcement, connected to the bounding frame; ii) single leaf clay brick with steel net in the plaster, connected to the bounding frame. The present paper details the first two tested solutions, along with the discussion of the results, focusing on the obtained collapse modes of the infills and the measured accelerations for those modes.

Avaliação do efeito das paredes de enchimento no comportamento dinâmico de edifícios de betão armado; Evaluation of the effect of masonry infills walls in the dynamic behavior of reinforced concrete buildings

Domingues, Julien
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Trabalho de Conclusão de Curso
Publicado em //2013 POR
Relevância na Pesquisa
47%
Dissertação de mestrado integrado em Engenharia Civil (área de especialização em Perfil de Estruturas e Geotecnia); Toda a história humana encontra-se recheada de eventos sísmicos que fustigaram as populações e a suas cidades de forma mais ou menos grave, dependendo da intensidade do sismo e da preparação das estruturas para resistirem. Perderem-se nesta luta travada contra a natureza e a sua implacável redundância um número bastante significativo de vidas humanas e danos materiais. Portugal, ao longo dos tempos, já prestou o seu tributo a esta triste causa e poderá no futuro encontrar-se novamente perante um evento sísmico de grandes proporções. A grande preocupação perante esta eventualidade é claramente o facto de o património edificado não estar a altura deste evento. Dentro dos edifícios modernos a maior preocupação, desencadeada em grande parte por recentes sismos em países vizinhos com resultados catastróficos, é a vulnerabilidade das paredes em alvenaria, pelo facto de poderem ceder segundo vários tipos de mecanismos de colapso. O objetivo deste trabalho é contribuir para o conhecimento da engenharia civil sobre o funcionamento destes elementos em particular e a sua influência no comportamento global das estruturas. Para tal...

A non-linear masonry infill macro-model to represent the global behaviour of buildings under cyclic loading

Rodrigues, H.; Varum, H.; Costa, A.
Fonte: Universidade de Aveiro Publicador: Universidade de Aveiro
Tipo: Conferência ou Objeto de Conferência
ENG
Relevância na Pesquisa
26.95%
The presence of masonry infill walls in RC buildings is very common. However, even nowadays, in the design of new buildings and in the assessment of existing ones, the infills are usually considered as non-structural elements and their influence in the structural response is ignored. For horizontal loading, infill panels can drastically modify the response, attracting forces to parts of the structure that have not been designed to resist them (Varum, 2003). In this paper is presented an improved non-linear numerical model for the simulation of the influence of the masonry infill walls in the seismic behaviour of structures, implemented in the analysis program PORANL. After the implementation and calibration of the proposed masonry model, it was performed a series non-linear dynamic analyses of a building, representative of the Modern Architecture. The main objective was to investigate the behaviour of this type of buildings, and their weakness under seismic loading. The building geometry and dimensions of the RC elements and infill walls were given in the original project, and were confirmed in the technical visits. The building studied has nine storeys and the structure is mainly composed by twelve plane frames oriented in the transversal direction. The building was analysed with a simplified plane model...

Extending displacement-based earthquake loss assessment (DBELA) for the computation of fragility curves

Silva, V.; Varum, H.; Crowley, H.; Pinho, R.
Fonte: Universidade de Aveiro Publicador: Universidade de Aveiro
Tipo: Conferência ou Objeto de Conferência
ENG
Relevância na Pesquisa
26.51%
This paper presents a new procedure to derive fragility functions for populations of buildings that relies on the displacement-based earthquake loss assessment (DBELA) methodology. In the method proposed herein, thousands of synthetic buildings have been produced considering the probabilistic distribution describing the variability in geometrical and material properties. Then, their nonlinear capacity has been estimated using the DBELA method and their response against a large set of ground motion records has been estimated. Global limit states are used to estimate the distribution of buildings in each damage state for different levels of ground motion, and a regression algorithm is applied to derive fragility functions for each limit state. The proposed methodology is demonstrated for the case of ductile and non-ductile Turkish reinforced concrete frames with masonry infills.

Irregularities Induced by Nonstructural Masonry Panels in Framed Buildings

NEGRO Paolo; COLOMBO Antonella
Fonte: Centro Comum de Pesquisa da Comissão Européia Publicador: Centro Comum de Pesquisa da Comissão Européia
Tipo: Articles in Journals Formato: Printed
ENG
Relevância na Pesquisa
37.08%
The effects of the nonstructural masonry infills on the global seismic behaviour of frame structures are discussed, based on the results of full-scale pseudodynamic tests and the post-test calculations. The tests were performed on a four-storey framed structure designed according to Eurocode 8, with different infill configurations. The results show that an irregular distribution of the panels yields unacceptably large damage in the frame. In addition, it is shown that even a regular distribution of infills can lead to irregular behaviour of the frame. The possibility to predict the behaviour of such structures by means of global models is explored. Based on the comparison of the experimental and numerical results a set of guidelines for calibrating the global models to reliably predict the behaviour of this class of structures is given.; JRC.(ISIS)-Institute For Systems, Informatics And Safety

How Reliable are Global Computer Models? Correlation with Large-Scale Tests.

NEGRO Paolo; COLOMBO Antonella
Fonte: Centro Comum de Pesquisa da Comissão Européia Publicador: Centro Comum de Pesquisa da Comissão Européia
Tipo: Articles in Journals Formato: Printed
ENG
Relevância na Pesquisa
26.51%
The pseudodynamic tests recently performed at the European Laboratory for structural Assessment provide an unprecedented wealth of experimental results against which computer models can be assessed.The paper focuses on the simplest nonlinear models for R/C structures.These are the most widely used , therefore calibration guidelines are badly needed. Moreover, since their use does not require particular mastery of numerical techniques, they may be used professional engineers as an alternative to the linear models that have almost exclusively adopted so far. In this paper the experimental results for a number of R/C structures (a full-scale four-story building, the same building with masonry infills, and four large-scale four-span regular and irregular bridges) are compared with the results which can be obtained by means of nonlinear analyses with simple global models. They proved to be simple and reliable. Some derived calibration guidelines for these models are presented, which may be used as a source of reference for studying similar ductile structures.; JRC.(ISIS)-Institute For Systems, Informatics And Safety

Seismic strengthening of RC buildings

TSIONIS Georgios; APOSTOLSKA ROBERTA; TAUCER Fabio
Fonte: Publications Office of the European Union Publicador: Publications Office of the European Union
Tipo: EUR - Scientific and Technical Research Reports Formato: Online
ENG
Relevância na Pesquisa
26.85%
A literature review on the seismic strengthening of reinforced concrete buildings, using steel bracings, infills and shear walls, is presented. Extensive experimental testing and numerical analyses of elements and structures have demonstrated the feasibility and effectiveness of all three measures for the increase of global strength and stiffness. In certain cases, they provide additional energy dissipation and help reducing irregularities. The selection of the most appropriate technique is based on desired performance levels and on economic and, possibly, other non-technical criteria. The results of previous studies clearly show that infilling an existing bay with reinforced concrete provides the highest increase in strength and stiffness. These studies also indicate that precast panels, steel bracings and masonry infills strengthened with fibre-reinforced polymers or textile-reinforced mortars are able to offer the same degree of improvement. The results available in literature, complemented by parametric numerical analyses, may provide the basis for the development of design guidelines with emphasis on strength and stiffness characteristics and on detailing of the connection between new and existing elements. Indeed, the development of models and their implementation in analysis software is a necessary step towards the wider application of these strengthening techniques. Regarding connections...

In-plane cyclic response of reinforced concrete frames with unreinforced masonry infills

Haider, Sarah
Fonte: Universidade Rice Publicador: Universidade Rice
ENG
Relevância na Pesquisa
47.61%
The in-plane cyclic response of reinforced concrete frames with unreinforced masonry infill was studied. Four full-scale reinforced concrete frame assemblies with masonry infills were designed and tested under reversed cyclic loading. The effect of panel aspect ratio and the stiffness of the infill relative to the frame were studied in terms of stiffness, strength, energy dissipation and failure mode. Based on the test results, an equivalent diagonal compression strut model was developed to represent the behavior of masonry infill bounded by a reinforced concrete frame and a simplified method for the linear-elastic analysis of R/C frames with masonry infills proposed. Using the experimental load-deformation plots, the hysteretic parameters relating to stiffness degradation, strength deterioration and pinching of the hysteretic loops were identified. These may be used to define the behavior of confined infills for the non-linear analysis of the infilled frames.

Evaluation, Modeling, and Retrofit of Flat-Slab Buildings subjected to Seismic Loading

Luo, Yuanhui
Fonte: Universidade Rice Publicador: Universidade Rice
Tipo: Thesis; Text Formato: application/pdf
ENG
Relevância na Pesquisa
26.51%
Flat-slab buildings designed and detailed for gravity loads only typically do not have the ability to resist moderate earthquakes without experiencing severe damage. The damage potential of such seismically deficient buildings therefore needs to be assessed and strategies developed to improve their seismic resistance. Punching failure at slab-column connections in non-ductile flat-slab buildings during earthquakes can trigger progressive collapse of floor slabs. Based on the test results of a large number of interior and exterior connections, a methodology is developed to predict shear and unbalanced moment-transfer capacities of connections under combined gravity and lateral loads. Furthermore, a frame analysis procedure is developed based on the equivalent frame concept which targets both the moment-transfer capacity as well as stiffness of the interior and exterior slab-column connections. The approach employs a parametric hysteretic model and is based on the effective slab-width concept. The proposed procedure for evaluating the seismic capacity of flat-slab connections and frames is verified by comparing the calculated and measured responses of two-bay flat-slab subassemblies tested under earthquake-type loading. Seismic reliability against punching failure of slab-column connections in flat-slab buildings designed for gravity loads was investigated using the proposed equivalent frame approach. The reliability analysis indicated that the flat-slab buildings constructed prior to the 1960's could experience significant damage during moderate intensity earthquakes. By limiting the gravity load on floor slabs and by controlling the lateral drift...

Experimental assessment of an innovative strengthening material for brick masonry infills

Martins, Andreia Piedade Gomes; Vasconcelos, Graça; Fangueiro, Raúl; Cunha, Fernando Eduardo Macedo
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2015 ENG
Relevância na Pesquisa
57.4%
The vulnerability of masonry infill walls has been highlighted in recent earthquakes in which severe inplane damage and out-of-plane collapse developed, justifying the investment in the proposal of strengthening solutions aiming to improve the seismic performance of these construction elements. Therefore, this work presents an innovative strengthening solution to be applied in masonry infill walls, in order to avoid brittle failure and thus minimize the material damage and human losses. The textilereinforced mortar technique (TRM) has been shown to improve the out-of-plane resistance of masonry and to enhance its ductility, and here an innovative reinforcing mesh composed of braided composite rods is proposed. The external part of the rod is composed of braided polyester whose structure is defined so that the bond adherence with mortar is optimized. The mechanical performance of the strengthening technique to improve the out-of-plane behaviour of brick masonry is assessed based on experimental bending tests. Additionally, a comparison of the mechanical behaviour of the proposed meshes with commercial meshes is provided. The idea is that the proposed meshes are efficient in avoiding brittle collapse and premature disintegration of brick masonry during seismic events.

Effectiveness of techniques for seismic strengthening of RC frame buildings

TSIONIS Georgios; TAUCER Fabio; APOSTOLSKA ROBERTA
Fonte: International Association for Bridge and Structural Engineering Publicador: International Association for Bridge and Structural Engineering
Tipo: Articles in periodicals and books Formato: CD-ROM
ENG
Relevância na Pesquisa
26.85%
The techniques for seismic strengthening of reinforced concrete buildings, namely steel braces, masonry infills and shear walls, are reviewed with the aim of assessing their effectiveness for the increase of global strength and stiffness and energy‐dissipation capacity and of providing guidance to designers regarding the most appropriate solution for practical applications. Although the results obtained by extensive experimental testing and numerical analyses of elements and structures present large scatter, they show that the highest performance improvement is provided by shear walls, followed by braces and infills. The review also highlights the issues that remain open in view of the development of design guidelines; the most important are the development of design tools and detailing rules for the connection between new and existing elements.; JRC.G.4-European laboratory for structural assessment

In-plane and out-of plane experimental characterization of rc masonry infilled frames

Akhound, Farhad; Vasconcelos, Graça; Lourenço, Paulo B.; Palha, Carlos Alberto Oliveira Fernandes; Silva, Luís C.
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em /07/2015 ENG
Relevância na Pesquisa
47.33%
Seismic investigations of typical south European masonry infilled frames were performed by testing two reduced scale specimens: one in the in-plane direction and another in the out-ofplane direction. Information about geometry and reinforcement scheme of those structures constructed in 1980s were obtained by [1]. The specimen to be tested in the in-plane direction was constructed as double leaf masonry while the specimen for testing in the out-of-plane direction is constructed with only its exterior leaf since the recent earthquakes have highlighted the vulnerability of the external leaf of the infills in out-of-plane direction [2]. The tests were performed by applying the pre-defined values of displacements in the in-plane and out-of-plane directions in the control points. For in-plane testing it was done by hydraulic actuator and for out-of-plane testing through the application of an airbag. Input and output air in the airbag was controlled by using a software to apply a specific displacement in the control point of the infill wall. Mid-point of the infill was assumed as a control point for outof- plane testing. Deformation and crack patterns of the infill confirm the formation of two-way arching mechanism of the masonry infill until collapse of the upper horizontal interface between infill and frame which is known as weakest interface due to difficulties in filling the mortar between bricks of last row and upper beam. This results in the crack opening through a welldefined path and the consequent collapse of the infill.

Blast loading of masonry infills: testing and simulation

Pereira, João Miguel; Campos, José; Lourenço, Paulo B.
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em /03/2015 ENG
Relevância na Pesquisa
37.28%
This work intends to present a newly developed test setup for dynamic out-of-plane loading using underWater Blast Wave Generators (WBWG) as loading source. Underwater blasting operations have been, during the last decades, subject of research and development of maritime blasting operations (including torpedo studies), aquarium tests for the measurement of blasting energy of industrial explosives and confined underwater blast wave generators. WBWG allow a wide range for the produced blast impulse and surface area distribution. It also avoids the generation of high velocity fragments and reduces atmospheric sound wave. A first objective of this work is to study the behavior of masonry infill walls subjected to blast loading. Three different masonry walls are to be studied, namely unreinforced masonry infill walls and two different reinforcement solutions. These solutions have been studied previously for seismic action mitigation. Subsequently, the walls will be simulated using an explicit finite element code for validation and parametric studies. Finally, a tool to help designers to make informed decisions on the use of infills under blast loading will be presented.