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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
46.36%
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.

Numerical validation of the experimental cyclic response of RC frames

Braz César, M.T.; Oliveira, Daniel V.; Barros, R.C.
Fonte: Saxe-Coburg Publications Publicador: Saxe-Coburg Publications
Tipo: Parte de Livro
ENG
Relevância na Pesquisa
66.76%
In this paper is estimated the numerical cyclic response of RC frames with and without masonry infill’s through a simplified nonlinear analysis using a commercial finite element method (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 for the bare frame and for the infill frame. To take into account the highly nonlinear behaviour of reinforced concrete (RC) frames due to large deformations, a numerical model based on the inelastic hinge method is used with a higher complexity of the hinge constitutive laws, which allows verifying the suitability of every hinge model to the experimental results.

Perfomance based design of building structural frames using static non-linear analysis

Barros, R.C.; Braz César, M.T.
Fonte: Civil-Comp Press Publicador: Civil-Comp Press
Tipo: Parte de Livro
ENG
Relevância na Pesquisa
36.51%
In the design of structures under seismic actions several methodologies can be used to describe the structural seismic response. The recent role of performance based design led to the development and use of methods based on non-linear analysis, namely the so-called pushover analysis. This analysis is a particularly realistic methodology to evaluate the seismic performance of a structural system since the time dependence of the structural behaviour, namely through material and/or geometric non-linearity, is included in the methodology. The pushover analysis is a simplified methodology to obtain the structural response to seismic actions through a non-linear static analysis. This analysis evaluates the performance of the structures through control of its displacements (at local and global levels), still giving information about the ductility and the resistant strength capacity. Several analysis methods have been proposed like the N2-method (Fajfar and Fischinger [1]) that is actually presented in Eurocode 8 (EC8) [2]. The implementation of this methodology in this regulation manifests the relevance of this analysis in the structural design. Therefore, the present study was developed to compile some information about this new dynamic structural analysis and design concept. In this context...

Application of lumped dissipation model in nonlinear analysis of reinforced concrete structures

ALVA, Gerson Moacyr Sisniegas; DEBS, Ana Lucia Homce de Cresce El
Fonte: ELSEVIER SCI LTD Publicador: ELSEVIER SCI LTD
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.16%
This paper deals with the application of the lumped dissipation model in the analysis of reinforced concrete structures, emphasizing the nonlinear behaviour of the materials The presented model is based on the original models developed by Cipollina and Florez-Lopez (1995) [12]. Florez-Lopez (1995) [13] and Picon and Florez-Lopez (2000) [14] However, some modifications were introduced in the functions that control the damage evolution in order to improve the results obtained. The efficiency of the new approach is evaluated by means of a comparison with experimental results on reinforced concrete structures such as simply supported beams, plane frames and beam-to-column connections Finally, the adequacy of the numerical model representing the global behaviour of framed structures is investigated and the limits of the analysis are discussed (C) 2009 Elsevier Ltd All rights reserved

Behavior of masonry infill panels in RC frames subjected to in plane and out of plane loads

Pereira, Manuel Fernando Paulo; Pereira, M. F. Neto; Ferreira, J. E. Dias; Lourenço, Paulo B.
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em //2011 ENG
Relevância na Pesquisa
66.76%
The building envelope in Europe is usually made of masonry walls, with enclosure and infill functions. Masonry walls have a major economical importance and contribute significantly to the building performance. Even if infill walls have no load-bearing function, they contribute significantly to the seismic behavior of buildings. Therefore, their adequate structural performance is needed, avoiding the occurrence of severe in-plane damage, with very large economical losses, and the out-of-plane expulsion, which additionally represents a large risk for human life. Recent earthquake codes in Europe require the safety assessment of non-structural elements (parapets, veneer masonry walls, infill walls, etc.), when their collapse entails risks for people or for the main structure. The Eurocode standards, entering the mandatory stage now, incorporate new requirements to be fulfilled by buildings or their parts. Such is the case of masonry infilled RC frames whose panels, according to Eurocode 8, are explicitly required to withstand the out-of-plane movement induced by earthquakes. Appropriate measures should be taken to avoid brittle failure and premature disintegration of the infill walls, as well as the partial or total out-of-plane collapse of slender masonry panels. This paper presents the experimental work and results achieved by applying cyclic out-ofplane loads to damaged masonry infilled RC frames. The masonry panels were previously damaged by applying an in-plane cyclic load after which the cyclic out-of- plane loads were applied. The frames and panels tested follow the traditional Portuguese RC structure construction system to which different types of reinforcement have been introduced in the panels.

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
26.61%
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...

Infill masonry : simple analytical methods for seismic design

Pereira, Manuel Fernando Paulo; Pereira, M. F. Neto; Ferreira, J. E. Dias; Lourenço, Paulo B.
Fonte: International Masonry Society Publicador: International Masonry Society
Tipo: Conferência ou Objeto de Conferência
Publicado em //2014 ENG
Relevância na Pesquisa
46.62%
The latest earthquake codes in Europe require the safety assessment of no-structural elements (parapets, masonry wall’s veneer, infill walls, etc.), as their collapse entails risks for people or for the main structure stability. This work made possible th e development of a design method, supported by previous experimental researches by applying cyclic out-of-plane loads to damaged masonry infill in RC frames. Panels tested reproduce Portuguese traditional RC structure construction system and two reinforced solutions were created as innovative solutions. The experimental campaign was carried out in order to determine: masonry properties; out-of-plane panel behaviour with previous in-plane damage; building behaviour subjected to dynamic tests performed in shaking table. Using finite element method to reproduce experimental tests and to broaden the range of samples it was possible to figure out equations according to parametric analysis which was able to reproduce in-plane and out-plane behaviour leading to an estimated load bearing capacity of each model and to determine frame strength and its stiffness. Those equations permit to design or verify the masonry infill panels in RC frames subjected to seismic loads.

Concrete-steel bond characterization of RC structural elements built with smooth plain reinforcement bars

Fernandes, C.; Varum, H.; Costa, A.
Fonte: Universidade de Aveiro Publicador: Universidade de Aveiro
Tipo: Conferência ou Objeto de Conferência
ENG
Relevância na Pesquisa
36.19%
Poor bond conditions often lead to damage and ultimately to collapse of reinforced concrete structures under seismic loading. Reinforced concrete elements built with smooth plain reinforcement bars are particularly sensitive to the effects of bond degradation. With the objective of evaluating the bond-slip influence in the dynamic response of RC frames, representative of existing structures built in Europe in the 50’s~70’s with smooth plain reinforcement bars, a series of numerical analysis were performed. A simplified numerical model was developed to account for the effects of bond-slip. The proposed model was calibrated with the results of PsD tests on a full-scale structure.

Experimental assessment and retrofit of full-scale models of existing RC frames

Pinto, A. V.; Varum, H.; Molina, J.
Fonte: Universidade de Aveiro Publicador: Universidade de Aveiro
Tipo: Conferência ou Objeto de Conferência
ENG
Relevância na Pesquisa
46.54%
PSD tests on two full-scale models of existing non-seismic resisting RC frame structures are described. The testing program covered several aspects, namely assessment of seismic performance of existing frames without and with infill panels, retrofitting of the bare frame using Selective Retrofitting techniques, strengthening of the infill panels using shotcrete and retrofitting of the frame using K-bracing with shear-link dissipators. The main results from the tests are summarized and discussed and the conclusions are drawn. The tests on the bare frame have shown how vulnerable are existing structures constructed in the 60’s and the beneficial effects of infill panels were confirmed from the tests on the infilled frame. Important improvements, in terms of seismic performance, were achieved by the retrofitting of the frames. However, it was also confirmed that strengthening of the existing infill panels in poorly detailed frames may lead to dangerous ‘local’ failures, such as the shear out of the external columns.

Simplified models for assessment and optimal redesign of irregular planar frames

Varum, H.; Pinto, A. V.; Costa, A.; Vila Real, P.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.19%
This paper presents a simplified methodology for predicting the response of buildings irregular in elevation, based on the non-linear dynamic multi-modal spectral seismic response of an equivalent simplified MDOF linear system. Making use of the MDOF model, it is also proposed a methodology for the optimum strengthening design of buildings, based on convex approximation methods. Three structural upgrading optimization problems (SUOPs) are implemented. The proposed models are validated against the results of a series of PsD tests carried out on a full-scale four-storey RC structure, representative of the construction practice in southern Mediterranean countries in Europe until the late 1960s.

Comparative analysis of RC irregular buildings designed according to different seismic design codes

Landingin, J.; Rodrigues, H.; Varum, H.; Arêde, A.; Costa, A.
Fonte: Faculty of Engineering, University of Porto Publicador: Faculty of Engineering, University of Porto
Tipo: Conferência ou Objeto de Conferência
ENG
Relevância na Pesquisa
56.66%
The present paper presents a comparison of the seismic provisions of the three seismic design codes, namely the Philippine code (National Structural Code of the Philippines or NSCP2010), the European code (Eurocode 8 or EC8), and American code (2009 International Building Code or 2009 IBC), to the most common ordinary residential building of standard occupancy. Two regular and irregular reinforced concrete (RC) frames were analysed and compared for four storey and eight storey buildings. The response spectrum function of NSCP 2010 was considered for the horizontal load action with different load combinations. Response spectrum analysis was performed using SAP2000 software package. Five representative columns for each RC frames were analyzed and based from the results of column axial load - bending moment interaction diagrams, EC8 was found to be conservative as compared to NSCP 2010 and 2009 IBC. The conclusion is that for the design and analysis of ordinary RC residential building with certain irregularity, EC8 provisions were considered to be safer.

Seismic assessment of rc structures with infill masonry panels in Nepal: sensitivity analysis

Chaulagain, Hemchandra; Rodrigues, Hugo; Spacone, Enrico; Varum, Humberto
Fonte: Universidade de Aveiro Publicador: Universidade de Aveiro
Tipo: Conferência ou Objeto de Conferência
ENG
Relevância na Pesquisa
46.57%
Reinforced concrete (RC) buildings in Nepal are constructed as RC frames with masonry infill panels. These structures exhibit a highly non-linear inelastic behaviour resulting from the interaction between the masonry infill panels and the surrounding frames. In this context, the paper presents an extensive case study of existing RC-framed buildings in a high seismic risk area in Nepal. A sensitivity analysis of the structures with masonry infill is performed. For this, the influence of different material properties is studied, namely diagonal compressive stress, modulus of elasticity and tensile stress of masonry infill panels. Result shows the influence on the structural behaviour particularly by variation of the diagonal compressive strength of infill masonry panels.

Nonlinear Earthquake Analysis of Reinforced Concrete Frames with Fiber and Bernoulli-Euler Beam-Column Element

Karaton, Muhammet
Fonte: Hindawi Publishing Corporation Publicador: Hindawi Publishing Corporation
Tipo: Artigo de Revista Científica
Publicado em 22/01/2014 EN
Relevância na Pesquisa
36.53%
A beam-column element based on the Euler-Bernoulli beam theory is researched for nonlinear dynamic analysis of reinforced concrete (RC) structural element. Stiffness matrix of this element is obtained by using rigidity method. A solution technique that included nonlinear dynamic substructure procedure is developed for dynamic analyses of RC frames. A predicted-corrected form of the Bossak-α method is applied for dynamic integration scheme. A comparison of experimental data of a RC column element with numerical results, obtained from proposed solution technique, is studied for verification the numerical solutions. Furthermore, nonlinear cyclic analysis results of a portal reinforced concrete frame are achieved for comparing the proposed solution technique with Fibre element, based on flexibility method. However, seismic damage analyses of an 8-story RC frame structure with soft-story are investigated for cases of lumped/distributed mass and load. Damage region, propagation, and intensities according to both approaches are researched.

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
36.36%
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

Seismic behaviour of reinforced concrete frames in Australia

Kashyap, J.; Griffith, M.; Ozbakkaloglu, T.
Fonte: AEES; Australia Publicador: AEES; Australia
Tipo: Conference paper
Publicado em //2008 EN
Relevância na Pesquisa
36.74%
Many intra-tectonic plate regions are considered to have low to moderate seismic risk. However, devastating earthquakes can occur in these regions and result in high consequences in terms of casualties and damage. This paper presents an experimental and analytical investigation to understand the seismic capacity of typically detailed Australian reinforced concrete (RC) frames. The experimental programme included a series of progressively increasing earthquake simulator tests, using base motion with design spectrum similar to that for firm soil sites in Australian design code. The analytical study consisted of inelastic time-history analyses of 3-, 5- and 12-storey RC frames with ground acceleration patterns based on artificially generated earthquake data for Boston region (on the east coast of the US). The main objectives of this research were (1) to investigate the behaviour of non-seismically designed RC frames under a 500 year return period (YRP) earthquake and (2) to determine the different magnitudes of earthquake (YRP) that are likely to cause excessive structural and nonstructural damage or collapse of gravity-load-designed (GLD) RC frames. The performance of the frames was analysed in relation to the drift limits, base shear...

Seismic Behaviour of a Full-Scale RC Frame Repaired Using CFRP Laminates

BALSAMO Alberto; COLOMBO Antonella; MANFREDI Gaetano; NEGRO PAOLO; PROTA Andrea
Fonte: ELSEVIER SCI LTD Publicador: ELSEVIER SCI LTD
Tipo: Articles in Journals Formato: Printed
ENG
Relevância na Pesquisa
36.29%
The opportunities provided by the use of Carbon Fiber Reinforced Polymer (CFRP) composites for the seismic repair of reinforced concrete (RC) structures were assessed on a full-scale dual system subjected to pseudodynamic tests in the ELSA laboratory. The aim of the CFRP repair was to recover the structural properties that the frame had before the seismic actions by providing both columns and joints with more deformation capacity. The repair was characterized by a selection of different fiber textures depending on the main mechanism controlling each component. The driving principles in the design of the CFRP repair and the outcomes of the experimental tests are presented in the paper. Comparisons between original and repaired structures are discussed in terms of global and local performance. In addition to the validation of the proposed technique, the experimental results will represent a reference database for the development of design criteria for the seismic repair of RC frames using composite materials.; JRC.G.5-European laboratory for structural assessment

Assessment and Retrofit of Full-scale Models of Existing RC Frames

PINTO VIEIRA ARTUR; TAUCER FABIO
Fonte: Springer Publicador: Springer
Tipo: Contributions to Conferences Formato: Printed
ENG
Relevância na Pesquisa
36.57%
Pseudo-dynamic (PSD) tests on two full-scale models representative of existing non-seismic resisting RC frame structures are described. The testing program covered several aspects, namely the assessment of seismic performance of existing frames without and with infill panels, retrofitting of a bare frame using Selective Retrofitting techniques, strengthening of infill panels using shotcrete and retrofitting of frames using K-bracing with shear-link dissipators. The main results from the PSD tests are summarized and discussed and conclusions are drawn. The tests on the bare and infilled frames showed the high vulnerability of existing structures constructed in the 60’s and confirmed the beneficial effects of infill panels. Important improvements, in terms of seismic performance, were achieved by retrofitting of the frames. However, strengthening of the existing infill panels in poorly detailed frames may lead to dangerous ‘local’ failures, such as shearing out of the external columns.; JRC.G.5-European laboratory for structural assessment

Seismic Behaviour of the Column-Foundation Connection of Pre-cast Industrial RC Frames

DIMOVA Silvia; NEGRO PAOLO; PINTO VIEIRA ARTUR
Fonte: FIB Publicador: FIB
Tipo: Contributions to Conferences Formato: CD-ROM
ENG
Relevância na Pesquisa
36.19%
The study is based on experimental results for the seismic response of a pre-cast single storey RC industrial frame and cyclic tests of pre-cast columns. The experimental data for the industrial frame have shown that under seismic excitations the curvatures below the top of the foundation exceed those above it. This fact cannot be explained only by the tensile strain penetration phenomenon. The records of the relative displacements at the bottom of the instrumented columns are used to estimate the contact forces acting on the faces of the columns connected to the pocket. The calculated contact forces differ significantly from their classic presentation as friction force when pressing force to the respective interface is applied. The presence of considerable contact forces at the tensed side of the columns is proved. This phenomenon is explained by the flexural deformation of the column surface, which applies pressure to the plane surface of the grout in their interaction. For small negative strains the surfaces of the column and the grout are coupled by a considerable contact force, which is linearly proportional to the strain and depends on the magnitude of the affected by the axial force initial deformation. Based on the considered experimental results...

Seismic Retrofitting of RC Frames with RC Infilling

CHRYSOSTOMOU Christis Z.; KYRIAKIDES Nicholas; KOTRONIS Panagiotis; POLJANSEK Martin; TAUCER Fabio; ROUSSIS Panayiotis; KOSMOPOULOS Antonis
Fonte: National Information Centre of Earthquake Engineering Publicador: National Information Centre of Earthquake Engineering
Tipo: Contributions to Conferences Formato: Online
ENG
Relevância na Pesquisa
36.76%
The effectiveness of seismic retrofitting of multi-storey multi-bay RC-frame buildings, by converting selected bays into new walls through infilling with RC, was studied experimentally at the ELSA facility at JRC, Ispra, and the results are reported here. The full-scale model tested with the pseudo-dynamic method consisted of two parallel frames, linked through 0.15m slabs, having three bays each (8.5m long), with the central bay (2.5m) infilled with RC wall, and being four storeys tall (12m). The frames were designed and detailed for gravity loads only and are typical of similar frames built in Cyprus in the 1970’s. Different connection details and reinforcement percentages for the two infilled frames were used in order to study the effects of these parameters. The results of the pseudo-dynamic and cyclic testing performed are presented and conclusions are drawn.; JRC.G.5-European laboratory for structural assessment

Seismic Retrofitting of RC Frames with RC Infilling (SERFIN Project) SERIES Transnational Access report

POLJANSEK Martin; TAUCER Fabio; MOLINA RUIZ Francisco Javier; CHRYSOSTOMOU Christis Z.; KYRIAKIDES Nicholas; ONOUFRIOU Toula; ROUSSIS Panayiotis; KOTRONIS Panagiotis; PANAGIOTAKOS Telemachos; KOSMOPOULOS Antonis
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
36.76%
The effectiveness of seismic retrofitting of multi-storey multi-bay RC-frame buildings by converting selected bays into new walls through infilling with reinforced concrete (RC) was studied experimentally at the ELSA facility of the Joint Research Centre in Ispra (Italy). A full-scale model was tested with the pseudo-dynamic method and consisted of two four-storey (12m tall) three-bay (8.5m long) parallel frames linked through 0.15m slabs with the central bay (2.5m) infilled with a RC wall. The frames were designed and detailed for gravity loads only and are typical of similar frames built in Cyprus in the 1970’s. Different connection details and reinforcement percentages for the two infilled frames were used in order to study their effects in determining structural response. The results of the pseudo-dynamic and cyclic tests performed on the specimen with the new walls show five times higher resistance to earthquake loads when compared to typical building construction in Cyprus in the 1970's.; JRC.G.5-European laboratory for structural assessment