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Comparison of cyclic response of reinforced concrete infilled frames with experimental results

Braz César, M.T.; Oliveira, Daniel V.; Barros, R.C.
Fonte: Instituto Politécnico de Bragança Publicador: Instituto Politécnico de Bragança
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.17%
This paper intends to estimate the numerical cyclic response of RC frames with and without masonry infill through a simplified nonlinear analysis using a commercial FEM package. The numerical model is based on the experiments carried out in the National Laboratory of Civil Engineering (LNEC) and the numerical and experimental results are compared to assess the accuracy of the simplified analysis based on the inelastic hinge method either for the bare frame and the infill frame.

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
46.47%
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 desempenho das envolventes dos edifícios face à acção dos sismos

Pereira, Manuel Fernando Paulo
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Tese de Doutorado
Publicado em 16/07/2013 POR
Relevância na Pesquisa
36.89%
Tese de doutoramento em Engenharia Civil; A envolvente dos edifícios em Portugal é constituída quase exclusivamente por paredes de alvenaria, que têm principalmente a função de vedação. Apesar de não terem função estrutural, as paredes ao interagirem com a estrutura, condicionam o comportamento sísmico dos edifícios, exigindo-se-lhe sob esta óptica, um desempenho adequado, evitando a ocorrência de danos severos nas paredes no seu plano, que conduzam a perdas económicas graves, e o colapso das paredes para fora do plano, que poderão colocar em perigo vidas humanas. Os actuais regulamentos estruturais europeus, no que concerne à segurança sísmica das estruturas exigem a verificação da segurança de elementos não estruturais quando o seu colapso acarreta riscos para pessoas ou para a estrutura principal. Os Eurocódigos estruturais quando entrarem na fase de implementação obrigatória irão impor novas exigências que deverão ser cumpridas pelos edifícios ou pelas suas partes. Tal é o caso das alvenarias de preenchimento, que deverão resistir ao movimento para fora do plano imposto pela acção dos sismos, devendo ser tomadas medidas adequadas para evitar a rotura prematura e desintegração das paredes de preenchimento...

Numerical modelling of masonry-infilled reinforced concrete frames : model calibration and parametric study

Akhoundi, Farhad; Lourenço, Paulo B.; Vasconcelos, Graça
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em //2014 ENG
Relevância na Pesquisa
126.86%
Generally two methods are proposed for analyzing the infilled frames; Micro modelling approach which finite element method is used to take into account local effects in detail and Macro modelling approach which is a very simplified method that takes into account the global behavior of the structure by replacing the infill with diagonal strut. In the present study a numerical analysis is carried out on a one bay one storey reinforced concrete frame with masonry infill under in-plane loading by using finite element modelling through the DIANA software. The numerical model was calibrated based on experimental results and then a parametric study was carried out, taking into account variation of material properties of infill and its height to length ratio. It is concluded that compressive strength and height to length ratio of the masonry infill has dominant role on the in-plane behavior of these types of masonry infilled frames. Increasing the compressive strength of the masonry enhances the lateral strength of the infilled frames while increasing the height to length ratio of the infill panel results in decrease of their lateral strength and initial stiffness.; Fundação para a Ciência e a Tecnologia (FCT)

Seismic behaviour of masonry infill walls : test and design

Leite, João C.
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Tese de Doutorado
Publicado em 28/07/2014 ENG
Relevância na Pesquisa
26.12%
Tese doutoramento em "Civil Engineering"; Several factors influence the behaviour of infilled frames, which has been studied in the last fifty years. One might assume that so many years of research in one theme might be enough to nearly fully understand it but this is not the case. The new generation of design standards, namely the Eurocode 8 (EC8), impose the use of reinforcement in these walls in order to prevent a brittle collapse and makes the structural engineer accountable for this requirement, yet it fails to provide enough information for the design. Motivated by the stated reasons, this thesis aims at understanding the seismic behaviour of infill walls when designed following the prescriptions of the EC8, therefore reinforced with bed joint and plaster reinforcement, and compares them to the seismic behaviour of the infill walls considered as a standard in the last three decades in Portugal, which is an unreinforced double leaf. For this purpose, three RC concrete buildings were constructed at a scale of 1:1.5 and tested on the shaking table of the National Laboratory for Civil Engineering, Portugal, each with a different infill solution but with the same geometry. Next, the experimental results were compared, in terms of demand and capacity...

Performance evaluation of retrofitting strategies for non-seismically designed RC buildings using steel braces

Varum, H.; Teixeira-Dias, F.; Marques, P.; Pinto, A.; Bhatti, A.
Fonte: Springer Verlag Publicador: Springer Verlag
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
26.12%
Recent major earthquakes around the world have evidenced that research in earthquake engineering must be directed to the vulnerability assessment of existing constructions lacking appropriate seismic resisting characteristics. Their retrofit or replacement should be made in order to reduce vulnerability, and consequent risk, to currently accepted levels. In this work, the efficiency of ductile steel eccentrically-braced systems in the seismic retrofitting of existing reinforced concrete (RC) buildings is studied. The retrofit technique studied consists in a bracing system with an energy dissipation device, designed to dissipate energy by shear deformation. The numerical model was calibrated with cyclic test results on a full-scale structure. The models used for the RC frame and masonry represent their real behavior and influence in the global structural response. The steel bracing system was modeled with strut rigid elements. The model for the energy dissipater device reproduces rigorously the behavior of the shear-link observed in the cyclic tests, namely in terms of shear, drift and energy dissipation. With the calibrated numerical model, a series of non-linear dynamic analyses were performed, for different earthquake input motions...

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

Silva, V.; Crowley, H.; Pinho, R.; Varum, H.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
26.12%
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. The recent developments in this methodology are also presented herein, such as the development of new formulae for the calculation of the yield period or the consideration of infilled frame structures. In the fragility method proposed herein, thousands of synthetic buildings have been produced considering probabilistic distributions describing the variability in their geometrical and material properties. Then, their nonlinear capacity has been estimated using the DBELA method and their performance against a large set of ground motion records has been calculated. 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 buildings with and without masonry infill walls, and compared with results obtained using nonlinear dynamic procedures and with the results from previous studies.

Numerical simulation of damage of low-rise RC frame structures with infilled masonry walls to explosive loads

Hao, H.; Wu, C.
Fonte: Institution of Engineers Australia Publicador: Institution of Engineers Australia
Tipo: Artigo de Revista Científica
Publicado em //2006 EN
Relevância na Pesquisa
46.54%
Terrorist bombing attacks on civilian structures could cause catastrophic effect with loss of lives and properties. Recent published US DoD (United States Department of Defence) anti-terrorist and US DoD Explosive Safety Guidelines give safe stand-off distance for building structure protection. However, the definition of structural damage and structural types and configurations in those guidelines is vague. To have a clearer picture of structural damage, it is therefore very important to carry out further studies to define damage severity of various structures under different explosion scenarios. As blasting tests are not only very expensive, but also in many cases not possible owing to safety consideration, predictions of structural damage with reliable numerical means become very important. In this study, numerical analysis of structural response and damage to surface explosions is carried out. A one-storey and a two-storey masonry infilled RC (reinforced concrete) frame are used as examples. Nonlinear orthotropic material model is employed to model RC frames and a homogenized masonry material model is used for masonry infilled walls. Strain-rate effect on RC material properties is included in the model. The commercial software LSDYNA3D (Whirley and Englemann 1991) with user defined material model subroutines is used to perform the numerical calculations. Structural damage levels corresponding to the various stand-off distances are defined from the numerical results. The results are also compared with the stand-off distances recommended in the US DoD Anti-Terrorist and Explosive Safety Guidelines.; © The Institution of Engineers Australia 2006

Numerical simulation of structural response and damage to simultaneous ground shock and airblast loads

Wu, C.; Hong, H.
Fonte: Pergamon-Elsevier Science Ltd Publicador: Pergamon-Elsevier Science Ltd
Tipo: Artigo de Revista Científica
Publicado em //2007 EN
Relevância na Pesquisa
26.26%
Current practice in analysis and design of structures to withhold surface explosions considers only airblast forces on structures. A surface explosion, in fact, generates both ground shock and airblast pressure on a nearby structure. In this paper, the influences of simultaneous ground shock and airblast forces on structural responses are investigated. Blast-induced surface ground motions and airblast pressures estimated in a previous study are employed as input in the analysis. A previously developed three-dimensional homogenized material model for a masonry wall including the equivalent elastic properties, strength envelope and damage threshold is used to model masonry wall. Another material damage model developed for reinforced concrete structures is used for modelling RC behavior due to explosive loads. These material models are programmed and linked to an available computer program LS-DYNA3D through its user subroutine capability. A one-story masonry infilled RC frame is used as an example in the study. Dynamic response and damage of the example structure to simultaneous ground shock and airblast forces, or separately to ground shock only or airblast forces only are calculated. It is found that in general, airblast load governs structural response and damage when the scaled distance is small. However...

Performance evaluation of retrofitting strategies for non-seismically designed RC buildings using steel braces

VARUM Humberto; TEIXEIRA-DIAS Filipe; MARQUES Paulo; PINTO VIEIRA Artur; QADIR-BHATTI Abdul
Fonte: SPRINGER Publicador: SPRINGER
Tipo: Articles in Journals Formato: Online
ENG
Relevância na Pesquisa
26.12%
Recent major earthquakes around the world have evidenced that research in earthquake engineering must be directed to the vulnerability assessment of existing constructions lacking appropriate seismic resisting characteristics. Their retrofit or replacement should be made in order to reduce vulnerability, and consequent risk, to currently accepted levels. In this work, the efficiency of ductile steel eccentrically-braced systems in the seismic retrofitting of existing reinforced concrete (RC) buildings is studied. The retrofit technique studied consists in a bracing system with an energy dissipation device, designed to dissipate energy by shear deformation. The numerical model was calibrated with cyclic test results on a full-scale structure. The models used for the RC frame and masonry represent their real behavior and influence in the global structural response. The steel bracing system was modeled with strut rigid elements. The model for the energy dissipater device reproduces rigorously the behavior of the shear-link observed in the cyclic tests, namely in terms of shear, drift and energy dissipation. With the calibrated numerical model, a series of non-linear dynamic analyses were performed, for different earthquake input motions...

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

Haider, Sarah
Fonte: Universidade Rice Publicador: Universidade Rice
ENG
Relevância na Pesquisa
56.66%
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.