Wallison A Medeiros | Universidade Estadual do Piauí (original) (raw)

Papers by Wallison A Medeiros

Fire and Materials, Dec 12, 2023

This paper reports an experimental campaign to evaluate the residual mechanical resistance after ... more This paper reports an experimental campaign to evaluate the residual mechanical resistance after high temperatures of two structural masonry components: block and mortar. Residual compressive strength and deformation modulus of four different hollow concrete blocks and two different mortar mixes after heating at high temperatures are investigated. The test method used was the one recommended by RILEM TC 200 for mortars and an adaptation of the same method proposed by Medeiros et al. suitable for the geometry of hollow blocks. Despite the sharp drop in the deformation modulus after heating blocks and mortar, no different behaviours are observed in the deformability of the materials caused by the variables studied. The same cannot be said in relation to the variation of the residual compressive strength of the blocks, which is affected by the variables: initial nominal compressive strength and width of the concrete block. Regarding laying mortars, the results confirmed the small influence of compressive strength on the evolution of residual mechanical strength. The data and analyses reported here on the residual mechanical properties of hollow concrete blocks produced from a concrete mixture of very dry consistency, vibro-pressed and with normal weight aggregates are relevant, since the data found in the literature generally refer to the wet cast concrete material and in cylindrical bodies.

Anais do 64° Congresso Brasileiro do Concreto, 2023

Este artigo apresenta um roteiro para o dimensionamento de muros de arrimo em alvenaria estrutura... more Este artigo apresenta um roteiro para o dimensionamento de muros de arrimo em alvenaria estrutural, com foco no uso de enrijecedores. A metodologia empregada envolveu um levantamento bibliográfico sobre o assunto e a revisão da norma ABNT NBR 16868: 2020 e outras normas pertinentes. O passo a passo para o projeto inclui a avaliação da geometria do muro, os carregamentos atuantes na estrutura e os esforços resultantes. O dimensionamento de painéis de alvenaria submetidos à flexão é abordado, levando em conta os esforços de compressão. Um exemplo prático de cálculo de muro de arrimo com enrijecedores é fornecido, com detalhamento das propriedades geométricas e armaduras. O artigo visa disponibilizar informações práticas para auxiliar profissionais e acadêmicos na construção de estruturas mais eficientes e seguras, também é possível perceber o baixo consumo de fôrmas e aço para muros de arrimos nestas dimensões. Palavra-Chave: muro de arrimo; alvenaria estrutural; enrijecedores; dimensionamento.

Fire and Materials, 2023

This paper reports an experimental campaign to evaluate the residual mechanical resistance after ... more This paper reports an experimental campaign to evaluate the residual mechanical resistance after high temperatures of two structural masonry components: block and mortar. Residual compressive strength and deformation modulus of four different hollow concrete blocks and two different mortar mixes after heating at high temperatures are investigated. The test method used was the one recommended by RILEM TC 200 for mortars and an adaptation of the same method proposed by Medeiros et al. suitable for the geometry of hollow blocks. Despite the sharp drop in the deformation modulus after heating blocks and mortar, no different behaviours are observed in the deformability of the materials caused by the variables studied. The same cannot be said in relation to the variation of the residual compressive strength of the blocks, which is affected by the variables: initial nominal compressive strength and width of the concrete block. Regarding laying mortars, the results confirmed the small influence of compressive strength on the evolution of residual mechanical strength. The data and analyses reported here on the residual mechanical properties of hollow concrete blocks produced from a concrete mixture of very dry consistency, vibro-pressed and with normal weight aggregates are relevant, since the data found in the literature generally refer to the wet cast concrete material and in cylindrical bodies.

Construction and Building Materials

The exposure of concrete to high temperatures negatively affects its mechanical properties, and t... more The exposure of concrete to high temperatures negatively affects its mechanical properties, and the factors that reduce these properties have been the subject of several studies over the years. Nevertheless, there are few studies on concrete for manufacturing blocks for structural masonry of very dry and vibro-pressed consistency. This paper shows the results of an experimental study on the mechanical strength and residual deformability modulus of hollow concrete blocks when exposed to temperatures from 100 to 800 °C. Three types of coarse aggregates—basalt, gneiss, and calcareous—were used, also varying the resistance of the inspected blocks − 12 MPa, 24 MPa, and 48 MPa. The differences in thermal and mechanical properties between concrete produced from a fluid mixture formed and consolidated in a mold, and concrete made of blocks for load-bearing masonry of very dry consistency and vibro-pressed are highlighted. The results also confirmed the low-level influence of compressive strength on the evolution of residual mechanical strength and the strong influence of the type of aggregate on this behavior. It was also found that the evaluation of residual thermal and mechanical properties of a wet-shaped concrete mixture to represent the behavior of dry and vibrated concrete, used in the manufacture of blocks for load-bearing masonry, can lead to unrepresentative results. There is no precedent for a study conducted with these parameters for this purpose that has applied such international recommendations.

Construction and Building Materials, 2023

The exposure of concrete to high temperatures negatively affects its mechanical properties, and t... more The exposure of concrete to high temperatures negatively affects its mechanical properties, and the factors that reduce these properties have been the subject of several studies over the years. Nevertheless, there are few studies on concrete for manufacturing blocks for structural masonry of very dry and vibro-pressed consistency. This paper shows the results of an experimental study on the mechanical strength and residual deformability modulus of hollow concrete blocks when exposed to temperatures from 100 to 800 °C. Three types of coarse aggregates—basalt, gneiss, and calcareous—were used, also varying the resistance of the inspected blocks − 12 MPa, 24 MPa, and 48 MPa. The differences in thermal and mechanical properties between concrete produced from a fluid mixture formed and consolidated in a mold, and concrete made of blocks for load-bearing masonry of very dry consistency and vibro-pressed are highlighted. The results also confirmed the low-level influence of compressive strength on the evolution of residual mechanical strength and the strong influence of the type of aggregate on this behavior. It was also found that the evaluation of residual thermal and mechanical properties of a wet-shaped concrete mixture to represent the behavior of dry and vibrated concrete, used in the manufacture of blocks for load-bearing masonry, can lead to unrepresentative results. There is no precedent for a study conducted with these parameters for this purpose that has applied such international recommendations.

Concreto & Construções, 2022

Engineering Structures, 2022

The behaviour of structural masonry walls reinforced with a ductile sustainable cementitious coat... more The behaviour of structural masonry walls reinforced with a ductile sustainable cementitious coating, called Ecofriendly Ductile Cementitious Composite (EDCC) is evaluated through Finite Element Modelling (FEM). EDCC is a sustainable material composed mostly by fly-ash and sand, with low cement content, used to repair masonry structures: it has excellent ductile behaviour due to the presence of polymeric fibres. Numerical models that can accurately simulate EDCC-reinforced masonry behaviour under compressive, flexural and shear loads were validated using previous experimental tests. A literature review was completed about the parameters defined for the component materials, interfaces and strategies that can be implemented to model structural masonry walls accurately, with the finite element method. Subsequently, the models were calibrated, comparing the results of stress vs strain or force vs displacement diagrams of experimental tests with numerical simulations. The models were able to simulate the masonry behaviour, with consistent results and failure modes. Parametric modelling was implemented to develop a formula capable of predicting the compressive load capacity of masonry walls strengthened with EDCC.

Repositório Institucional UFSCar, 2022

The present work aims to investigate, in laboratory, of structural concrete blocks submitted to h... more The present work aims to investigate, in laboratory, of structural concrete blocks submitted to high temperatures to contribute with relevant information for the design of structural masonry in a fire situation. Since Brazil still does not have a national standard for masonry design in a fire situation, a first study was carried out, applying international standards for the Brazilian context. However, this approach must be carried out with caution, as there are significant differences in materials and procedures in civil construction in each country. In the second study, knowing that the material present in the hollow concrete blocks has, due to its geometry and manufacturing process, intrinsic properties that differ from the wet cast concrete material, a methodology is developed to evaluate and obtain, in laboratory, of the mechanical resistance of concrete blocks under high temperatures in a more adequate way. Then, in a third study, the thermal and physical properties of dry vibrated concrete, consisting of different types of coarse aggregate (basalt, limestone, and gneiss) and three different strength classes of blocks (6, 12 and 24 MPa) are investigated; comparing and evaluating the similarities and differences with wet cast concrete. The particularities of dry concrete used in the manufacture of masonry blocks showed significant differences in some analyzes due to their peculiarities in terms of porosity, humidity, density, etc. Based on the methodology properly developed to evaluate hollow concrete blocks, a fourth study was carried out to evaluate the influence that the type of coarse aggregate and the resistance class of the blocks, after heating, exert on the residual mechanical strength. It was observed that the mechanical behavior of hollow concrete blocks differs, to a certain degree, from the residual mechanical behavior found in the literature for wet cast concrete. Hollow concrete blocks tend to maintain compressive strength from room temperature to higher temperatures, 300°C for siliceous aggregates and 400°C for limestone aggregates. With the parameters obtained in the previous phases of the study, which served as a starting point in the approach of thermal models, in the fifth study, it was possible to determine isotherms of the concrete blocks by numerical models calibrated from experimental results. In this way, a numerical approach to verify in a simplified way the resistance of concrete blocks in fire situation by analytical method is presented. The data and analyzes reported on methodology, residual thermal and mechanical properties of hollow concrete blocks produced from a concrete mixture of very dry consistency, vibro-pressed and with normal weight aggregates, are new and unprecedented to enable the understanding of the behavior of Brazilian blocks and guide future research

Concreto e Construção, 2022

A normalização nacional ainda não contempla procedimentos de cálculo para determinação do Tempo d... more A normalização nacional ainda não contempla procedimentos de cálculo para determinação do Tempo de Resistência ao Fogo (TRF) em paredes de alvenaria estrutural no que se refere à isolação térmica. Contudo, a aplicação direta de normas estrangeiras, sem prévia análise de compatibilidade às construções brasileiras, pode originar métodos não seguros. Neste trabalho, investigou-se a aplicação do Método ACI/TMS 216.1 a resultados obtidos em ensaios nacionais e propôs-se, como sugestão para futura Parte 4 da ABNT NBR 16868, um procedimento simplificado de cálculo. Ao todo 12 ensaios foram investigados, detalhando-se características da disposição das unidades, das paredes em si e dos revestimentos. Os resultados reais foram comparados com os calculados e as situações relevantes foram analisadas. Em função dos poucos ensaios existentes e das diferenças associadas aos materiais e práticas construtivas adotadas internacionalmente, adaptações a favor da segurança foram realizadas, culminando em uma proposta coerente com os resultados obtidos para verificação da alvenaria estrutural com blocos de concreto em um contexto nacional.

Matéria (Rio de Janeiro)

RESUMO O comportamento da alvenaria estrutural resulta do desempenho de cada componente: unidades... more RESUMO O comportamento da alvenaria estrutural resulta do desempenho de cada componente: unidades, juntas de argamassa, grautes e armaduras. Comercialmente, os blocos para alvenaria são produzidos com concreto seco ou zero-slump. Sua dosagem e propriedades físicas se diferem consideravelmente dos concretos convencionais e dependem da eficiência de compactação das máquinas vibroprensas. Ensaiar elementos de alvenaria em tamanho natural é dispendioso e requer uma infraestrutura específica. Nessa perspectiva, modelagens computacionais baseadas em formulações numéricas como o Método dos Elementos Finitos (FEM) podem se tornar alternativas viáveis e de grande potencial. Este trabalho objetiva analisar numérica e experimentalmente a influência do tipo de agregado nas propriedades físicas e, sobretudo, mecânicas (módulo secante e resistência à compressão) de blocos vazados de concreto para alvenaria estrutural. Foram testadas três resistências de bloco (6, 12 e 24 MPa), contendo três tipos...

Discorre-se sobre o modulo de elasticidade e sua influencia no efeito de segunda ordem nas edific... more Discorre-se sobre o modulo de elasticidade e sua influencia no efeito de segunda ordem nas edificacoes e no deslocamento de topo de edificios sob a perspectiva da ABNT NBR 6118/2014, que recomenda maior ou menor rigidez em funcao do agregado do concreto. Para tal analise, utiliza-se um edificio modelo de 16 pavimentos e planta simetrica. Um modelo de referencia e idealizado, com o modulo de elasticidade intermediario que segue a norma anterior de estruturas de concreto ABNT NBR 6118/2007 e entao analises adicionais com valor maximo e minimo de rigidez baseado apenas no agregado. Os efeitos de segunda ordem sao avaliados com o coeficiente γz e do processo P-Delta, realizado com o software SAP2000. O modelo atribui menor resistencia e rigidez para o concreto nos pavimentos superiores, simulando uma pratica de projeto comum. Os resultados sao confrontados com modelo de referencia. Assim como ja consolidado, em primeira ordem a relacao entre modulo de elasticidade e deslocamento de topo...

Parâmetros de projeto de alvenaria estrutural com blocos de concreto, 2021

Esta é a segunda edição, revisada e ampliada, deste livro, que continua com a parceria entre a As... more Esta é a segunda edição, revisada e ampliada, deste livro, que continua com a parceria entre a Associação Brasileira de Cimento Portland (ABCP) e a Universidade Federal de São Carlos (UFSCar), que juntas desenvolvem projeto cujo objetivo é disponibilizar ao meio técnico um manual de melhores práticas para projeto de edifícios de alvenaria estrutural, com ênfase na utilização dos blocos de concreto. Após nove anos, esta nova edição está sendo finalizada em momento bastante oportuno, pois foi possível levar em conta a última atualização e unificação das principais normas brasileiras sobre o assunto que deram origem à recente norma ABNT NBR 16868 – Alvenaria Estrutural – Parte 1: Projeto; Parte 2: Execução e controle de obras; e Parte 3: Métodos de ensaio. Foram mantidos o formato e a sequência da edição anterior, porém o conteúdo deste livro sofreu uma revisão ampla do texto e exercícios para adaptá-lo às prescrições da norma ABNT NBR 16868:2020, da qual os autores tiveram ampla participação. As informações sobre detalhes e escolhas de projetistas com notoriedade em projetos de edifícios de alvenaria estrutural foram compiladas e melhoradas para o contexto atual em que o avanço de tecnologias e dos materiais permitiu a adoção de novas soluções no projeto e no processo construtivo. O livro continua condensando a experiência de renomados projetistas de edifícios em alvenaria estrutural, e espera-se que continue possibilitando que construtoras e engenheiros de obras tirem suas dúvidas e possam melhor discutir os detalhes com seus projetistas.

Materials and Structures, 2022

The fire behavior of a structural masonry building has a positive relationship with the behavior ... more The fire behavior of a structural masonry building has a positive relationship with the behavior of its constituent materials under high temperatures. Assessing the residual mechanical strength of the structural masonry components is essential, following the exposure to high temperatures. This work proposes to examine the standard for the determination of the mechanical properties (compressive strength and elastic modulus) of concrete blocks under high temperatures. Based on the existing recommendations (RILEM Technical Committee in Mater Struct 40: 841–853, 2007. 10.1617/s11527-007-9285-2, Mater Struct 40: 855–864, 2007. 10.1617/s11527-007-9286-1, Mater Struct 28: 410–414, 1995, Mater Struct 33: 219–223, 2000, Mater Struct 37: 139–144, 2004. 10.1007/bf02486610, Mater Struct 30: 17–21, 1997. 10.1007/bf02539270, Mater Struct 31: 290–295, 1998, Mater Struct 33: 6–13, 2000, Mater Struct 33: 224–228, 2000, Mater Struct 38: 913–919, 2005. 10.1617/14363RILEM Technical Committee (2007), Recommendation of RILEM TC 200-HTC in Mater Struct 40: 449–458, 2007. 10.1617/s11527-006-9203-z), an extensive experimental program was proposed to guide the adaptation of these recommendations to the case of concrete blocks, with emphasis on the heating and cooling rate of the samples. Suggestions of parameters necessary for laboratory evaluation of residual mechanical strength at elevated temperatures are presented for the hollow concrete block (HCB): number of specimens, testing age, storage conditions, rate of temperature rise with the time for heating the samples, suggestions of internal instrumentation of the equipment for the effective control of this rate and guaranteeing uniformity of heating.

International Journal of Masonry Research and Innovation, 2021

In Brazil, structural masonry is widely used in the construction of tall buildings. As the countr... more In Brazil, structural masonry is widely used in the construction of tall buildings. As the country does not have its own standard for masonry in a fire situation, the Fire Department recommends that the design of masonry structures in a fire situation be carried out in accordance with the instructions of Eurocode or similar international standard. This article critically analyses the adoption of design procedures in use in the USA, Australia and Europe for a typical Brazilian masonry structure, verifying the applicability of these codes and taking into account the differences in aggregates used in blocks and finishes, aiming to support discussions on Brazilian standardisation, in addition to comparing the different ways of approaching each standard. The results showed that it is possible to use international codes, but their use will not always portray the real situation, requiring the sector and the technical-scientific community urgently unite to address this issue.

In the last decades, several studies have been developed regarding structures composed by frames ... more In the last decades, several studies have been developed regarding structures composed by frames infilled with masonry walls, proving the increase of lateral stiffness by the infill. In this work, an analysis was carried out, based on design codes which adopt the equivalent diagonal strut method, to compare theoretical results with experimental ones of tests performed on steel frames infilled with concrete block masonry. Two of the three assessed codes specify lateral stiffness smaller than that measured from experimental testing, as safety measures for design. Regarding the masonry ultimate loads, the two specifications analyzed yielded similar values of critical force, although they pointed out different failure modes. The equivalent diagonal strut method has been proved to be a simple and useful tool for considering masonry walls and it should be used in case of reduced horizontal loads, prior to initial cracks of the infill wall.

Brick and Block Masonry - From Historical to Sustainable Masonry, 2020

In Brazil, one of the most used aggregates in the concrete blocks production is gneiss. There is ... more In Brazil, one of the most used aggregates in the concrete blocks production is gneiss. There is few information in literature about the behavior of concrete blocks with this type of aggregate at high temperatures. Besides that, the test procedures to determine the concrete stress-strain curve is generally prescribed for cylindrical cast specimens. The concrete's properties in this type samples are different from those produced in concrete block industries that use large vibrating presses with strong compaction energy and low cement consumption. This paper describes the effects of temperature on the mechanical properties of concrete blocks made with gneiss aggregate. For this, the CMUs were heated to 800°C and their residual compression strength and deformability was determined. The test method was adapted from the RILEM TC 200-HTC recommendations. In conclusion, the aggregate was thermally stable, and the residual compressive strength of the concrete block was basically unchanged below 400°C.

Construction and Building Materials, 2020

Abstract Flat-jack testing is considered efficient in the analysis of historical masonry built wi... more Abstract Flat-jack testing is considered efficient in the analysis of historical masonry built with stones or solid bricks. The advantage of this technique is obtaining important properties to a structural analysis, such as the stress-strain curve of the wall, masonry modulus of elasticity and an estimate compressive strength, without any permanent damage to the structure. Due to its advantages, the technique could also be applied in modern masonry, but the current available equipment has limitations in its geometry and maximum applied pressure. This paper presents the development and application of a new flat-jack equipment, that can fit hollow blocks and allow applying high pressures of more than 20 MPa, way more than the usual flat-jack limit of 5 to 7 MPa. The developed flat-jack was used to test hollow concrete-block masonry to evaluate masonry strength and elastic modulus values, that were compared to values obtained from destructive testing also performed. A good correlation on both results was observed. Based on the experimental results and using the Abaqus FEM package, a detailed micro modelling is presented considering the masonry units, mortar and their interfaces. The numerical model was able to successfully capture crack pattern and strain and stress distribution of the walls in good agreement with the experimental results. Both on the experimental and numerical analyses the testing procedure on where to clean the mortar joints, on the top-bottom of the tested area or also at the lateral vertical joint of the region, was assessed. Result indicate the success and validation of using flat-jack application in modern high-strength hollow block masonry, as far as we know for the first time, and point suggestions on were the cut the mortar joint before testing.

PARC Pesquisa em Arquitetura e Construção, 2018

O presente trabalho apresenta estudo sobre alvenaria estrutural construída dentro de pórticos em ... more O presente trabalho apresenta estudo sobre alvenaria estrutural construída dentro de pórticos em concreto pré-moldado dimensionada como parte do sistema de contraventamento das edificações, definindo esse tipo de elemento como Alvenaria Participante. São identificados os principais detalhes construtivos das paredes de alvenaria participante que influenciam o comportamento do pórtico pré-moldado frente às ações horizontais. No Brasil, a contribuição dessas paredes não é considerada no dimensionamento da estrutura devido à falta de informações e à sua complexidade, o que leva a projetos mais conservadores. Neste estudo, identifica-se os principais detalhes construtivos das paredes de alvenaria participante que influenciam no contraventamento das edificações. Também, são consideradas as variáveis e mecanismos que algumas das principais normas internacionais utilizam na análise de alvenaria participante em pórticos para a estabilidade das estruturas. Além de, realizar a comparação entre...

Anais do Workshop De Tecnologia De Processos E Sistemas Construtivos, 2017

No Brasil, tem-se observado o crescente uso de elementos pré-fabricados de concreto, nesse contex... more No Brasil, tem-se observado o crescente uso de elementos pré-fabricados de concreto, nesse contexto, encontram-se os painéis de parede dupla pré-moldados que são um sistema construtivo formado por duas placas de concreto de pequena espessura mantidas unidas através de armadura treliçada. A armação estrutural necessária para todo o painel é construída dentro do componente pré-fabricado e após a instalação dos painéis, o espaço entre as placas pode ou não ser preenchido com concreto misturado e despejado no local da obra; neste sentido, o painel de parede dupla é um componente semi pré-fabricado. Esses painéis de fato combinam as maiores vantagens da pré-fabricação com as de uma parede fabricada em moldes concretados na obra. O presente trabalho apresenta uma investigação exploratória realizada através de revisão bibliográfica na qual será descrito e verificado as indicações de desempenho dos painéis de parede dupla pré-moldado conforme a recém lançada norma ABNT NBR 16475:2017, analisando criticamente os aspectos abordados e as lacunas deixadas pela a mesma; tendo com isto, o intuito de contribuir com a sistematização e difusão do tema na comunidade da construção civil brasileira.

Anais do Workshop De Tecnologia De Processos E Sistemas Construtivos, 2017

Fire and Materials, Dec 12, 2023

This paper reports an experimental campaign to evaluate the residual mechanical resistance after ... more This paper reports an experimental campaign to evaluate the residual mechanical resistance after high temperatures of two structural masonry components: block and mortar. Residual compressive strength and deformation modulus of four different hollow concrete blocks and two different mortar mixes after heating at high temperatures are investigated. The test method used was the one recommended by RILEM TC 200 for mortars and an adaptation of the same method proposed by Medeiros et al. suitable for the geometry of hollow blocks. Despite the sharp drop in the deformation modulus after heating blocks and mortar, no different behaviours are observed in the deformability of the materials caused by the variables studied. The same cannot be said in relation to the variation of the residual compressive strength of the blocks, which is affected by the variables: initial nominal compressive strength and width of the concrete block. Regarding laying mortars, the results confirmed the small influence of compressive strength on the evolution of residual mechanical strength. The data and analyses reported here on the residual mechanical properties of hollow concrete blocks produced from a concrete mixture of very dry consistency, vibro-pressed and with normal weight aggregates are relevant, since the data found in the literature generally refer to the wet cast concrete material and in cylindrical bodies.

Anais do 64° Congresso Brasileiro do Concreto, 2023

Este artigo apresenta um roteiro para o dimensionamento de muros de arrimo em alvenaria estrutura... more Este artigo apresenta um roteiro para o dimensionamento de muros de arrimo em alvenaria estrutural, com foco no uso de enrijecedores. A metodologia empregada envolveu um levantamento bibliográfico sobre o assunto e a revisão da norma ABNT NBR 16868: 2020 e outras normas pertinentes. O passo a passo para o projeto inclui a avaliação da geometria do muro, os carregamentos atuantes na estrutura e os esforços resultantes. O dimensionamento de painéis de alvenaria submetidos à flexão é abordado, levando em conta os esforços de compressão. Um exemplo prático de cálculo de muro de arrimo com enrijecedores é fornecido, com detalhamento das propriedades geométricas e armaduras. O artigo visa disponibilizar informações práticas para auxiliar profissionais e acadêmicos na construção de estruturas mais eficientes e seguras, também é possível perceber o baixo consumo de fôrmas e aço para muros de arrimos nestas dimensões. Palavra-Chave: muro de arrimo; alvenaria estrutural; enrijecedores; dimensionamento.

Fire and Materials, 2023

This paper reports an experimental campaign to evaluate the residual mechanical resistance after ... more This paper reports an experimental campaign to evaluate the residual mechanical resistance after high temperatures of two structural masonry components: block and mortar. Residual compressive strength and deformation modulus of four different hollow concrete blocks and two different mortar mixes after heating at high temperatures are investigated. The test method used was the one recommended by RILEM TC 200 for mortars and an adaptation of the same method proposed by Medeiros et al. suitable for the geometry of hollow blocks. Despite the sharp drop in the deformation modulus after heating blocks and mortar, no different behaviours are observed in the deformability of the materials caused by the variables studied. The same cannot be said in relation to the variation of the residual compressive strength of the blocks, which is affected by the variables: initial nominal compressive strength and width of the concrete block. Regarding laying mortars, the results confirmed the small influence of compressive strength on the evolution of residual mechanical strength. The data and analyses reported here on the residual mechanical properties of hollow concrete blocks produced from a concrete mixture of very dry consistency, vibro-pressed and with normal weight aggregates are relevant, since the data found in the literature generally refer to the wet cast concrete material and in cylindrical bodies.

Construction and Building Materials

The exposure of concrete to high temperatures negatively affects its mechanical properties, and t... more The exposure of concrete to high temperatures negatively affects its mechanical properties, and the factors that reduce these properties have been the subject of several studies over the years. Nevertheless, there are few studies on concrete for manufacturing blocks for structural masonry of very dry and vibro-pressed consistency. This paper shows the results of an experimental study on the mechanical strength and residual deformability modulus of hollow concrete blocks when exposed to temperatures from 100 to 800 °C. Three types of coarse aggregates—basalt, gneiss, and calcareous—were used, also varying the resistance of the inspected blocks − 12 MPa, 24 MPa, and 48 MPa. The differences in thermal and mechanical properties between concrete produced from a fluid mixture formed and consolidated in a mold, and concrete made of blocks for load-bearing masonry of very dry consistency and vibro-pressed are highlighted. The results also confirmed the low-level influence of compressive strength on the evolution of residual mechanical strength and the strong influence of the type of aggregate on this behavior. It was also found that the evaluation of residual thermal and mechanical properties of a wet-shaped concrete mixture to represent the behavior of dry and vibrated concrete, used in the manufacture of blocks for load-bearing masonry, can lead to unrepresentative results. There is no precedent for a study conducted with these parameters for this purpose that has applied such international recommendations.

Construction and Building Materials, 2023

The exposure of concrete to high temperatures negatively affects its mechanical properties, and t... more The exposure of concrete to high temperatures negatively affects its mechanical properties, and the factors that reduce these properties have been the subject of several studies over the years. Nevertheless, there are few studies on concrete for manufacturing blocks for structural masonry of very dry and vibro-pressed consistency. This paper shows the results of an experimental study on the mechanical strength and residual deformability modulus of hollow concrete blocks when exposed to temperatures from 100 to 800 °C. Three types of coarse aggregates—basalt, gneiss, and calcareous—were used, also varying the resistance of the inspected blocks − 12 MPa, 24 MPa, and 48 MPa. The differences in thermal and mechanical properties between concrete produced from a fluid mixture formed and consolidated in a mold, and concrete made of blocks for load-bearing masonry of very dry consistency and vibro-pressed are highlighted. The results also confirmed the low-level influence of compressive strength on the evolution of residual mechanical strength and the strong influence of the type of aggregate on this behavior. It was also found that the evaluation of residual thermal and mechanical properties of a wet-shaped concrete mixture to represent the behavior of dry and vibrated concrete, used in the manufacture of blocks for load-bearing masonry, can lead to unrepresentative results. There is no precedent for a study conducted with these parameters for this purpose that has applied such international recommendations.

Concreto & Construções, 2022

Engineering Structures, 2022

The behaviour of structural masonry walls reinforced with a ductile sustainable cementitious coat... more The behaviour of structural masonry walls reinforced with a ductile sustainable cementitious coating, called Ecofriendly Ductile Cementitious Composite (EDCC) is evaluated through Finite Element Modelling (FEM). EDCC is a sustainable material composed mostly by fly-ash and sand, with low cement content, used to repair masonry structures: it has excellent ductile behaviour due to the presence of polymeric fibres. Numerical models that can accurately simulate EDCC-reinforced masonry behaviour under compressive, flexural and shear loads were validated using previous experimental tests. A literature review was completed about the parameters defined for the component materials, interfaces and strategies that can be implemented to model structural masonry walls accurately, with the finite element method. Subsequently, the models were calibrated, comparing the results of stress vs strain or force vs displacement diagrams of experimental tests with numerical simulations. The models were able to simulate the masonry behaviour, with consistent results and failure modes. Parametric modelling was implemented to develop a formula capable of predicting the compressive load capacity of masonry walls strengthened with EDCC.

Repositório Institucional UFSCar, 2022

The present work aims to investigate, in laboratory, of structural concrete blocks submitted to h... more The present work aims to investigate, in laboratory, of structural concrete blocks submitted to high temperatures to contribute with relevant information for the design of structural masonry in a fire situation. Since Brazil still does not have a national standard for masonry design in a fire situation, a first study was carried out, applying international standards for the Brazilian context. However, this approach must be carried out with caution, as there are significant differences in materials and procedures in civil construction in each country. In the second study, knowing that the material present in the hollow concrete blocks has, due to its geometry and manufacturing process, intrinsic properties that differ from the wet cast concrete material, a methodology is developed to evaluate and obtain, in laboratory, of the mechanical resistance of concrete blocks under high temperatures in a more adequate way. Then, in a third study, the thermal and physical properties of dry vibrated concrete, consisting of different types of coarse aggregate (basalt, limestone, and gneiss) and three different strength classes of blocks (6, 12 and 24 MPa) are investigated; comparing and evaluating the similarities and differences with wet cast concrete. The particularities of dry concrete used in the manufacture of masonry blocks showed significant differences in some analyzes due to their peculiarities in terms of porosity, humidity, density, etc. Based on the methodology properly developed to evaluate hollow concrete blocks, a fourth study was carried out to evaluate the influence that the type of coarse aggregate and the resistance class of the blocks, after heating, exert on the residual mechanical strength. It was observed that the mechanical behavior of hollow concrete blocks differs, to a certain degree, from the residual mechanical behavior found in the literature for wet cast concrete. Hollow concrete blocks tend to maintain compressive strength from room temperature to higher temperatures, 300°C for siliceous aggregates and 400°C for limestone aggregates. With the parameters obtained in the previous phases of the study, which served as a starting point in the approach of thermal models, in the fifth study, it was possible to determine isotherms of the concrete blocks by numerical models calibrated from experimental results. In this way, a numerical approach to verify in a simplified way the resistance of concrete blocks in fire situation by analytical method is presented. The data and analyzes reported on methodology, residual thermal and mechanical properties of hollow concrete blocks produced from a concrete mixture of very dry consistency, vibro-pressed and with normal weight aggregates, are new and unprecedented to enable the understanding of the behavior of Brazilian blocks and guide future research

Concreto e Construção, 2022

A normalização nacional ainda não contempla procedimentos de cálculo para determinação do Tempo d... more A normalização nacional ainda não contempla procedimentos de cálculo para determinação do Tempo de Resistência ao Fogo (TRF) em paredes de alvenaria estrutural no que se refere à isolação térmica. Contudo, a aplicação direta de normas estrangeiras, sem prévia análise de compatibilidade às construções brasileiras, pode originar métodos não seguros. Neste trabalho, investigou-se a aplicação do Método ACI/TMS 216.1 a resultados obtidos em ensaios nacionais e propôs-se, como sugestão para futura Parte 4 da ABNT NBR 16868, um procedimento simplificado de cálculo. Ao todo 12 ensaios foram investigados, detalhando-se características da disposição das unidades, das paredes em si e dos revestimentos. Os resultados reais foram comparados com os calculados e as situações relevantes foram analisadas. Em função dos poucos ensaios existentes e das diferenças associadas aos materiais e práticas construtivas adotadas internacionalmente, adaptações a favor da segurança foram realizadas, culminando em uma proposta coerente com os resultados obtidos para verificação da alvenaria estrutural com blocos de concreto em um contexto nacional.

Matéria (Rio de Janeiro)

RESUMO O comportamento da alvenaria estrutural resulta do desempenho de cada componente: unidades... more RESUMO O comportamento da alvenaria estrutural resulta do desempenho de cada componente: unidades, juntas de argamassa, grautes e armaduras. Comercialmente, os blocos para alvenaria são produzidos com concreto seco ou zero-slump. Sua dosagem e propriedades físicas se diferem consideravelmente dos concretos convencionais e dependem da eficiência de compactação das máquinas vibroprensas. Ensaiar elementos de alvenaria em tamanho natural é dispendioso e requer uma infraestrutura específica. Nessa perspectiva, modelagens computacionais baseadas em formulações numéricas como o Método dos Elementos Finitos (FEM) podem se tornar alternativas viáveis e de grande potencial. Este trabalho objetiva analisar numérica e experimentalmente a influência do tipo de agregado nas propriedades físicas e, sobretudo, mecânicas (módulo secante e resistência à compressão) de blocos vazados de concreto para alvenaria estrutural. Foram testadas três resistências de bloco (6, 12 e 24 MPa), contendo três tipos...

Discorre-se sobre o modulo de elasticidade e sua influencia no efeito de segunda ordem nas edific... more Discorre-se sobre o modulo de elasticidade e sua influencia no efeito de segunda ordem nas edificacoes e no deslocamento de topo de edificios sob a perspectiva da ABNT NBR 6118/2014, que recomenda maior ou menor rigidez em funcao do agregado do concreto. Para tal analise, utiliza-se um edificio modelo de 16 pavimentos e planta simetrica. Um modelo de referencia e idealizado, com o modulo de elasticidade intermediario que segue a norma anterior de estruturas de concreto ABNT NBR 6118/2007 e entao analises adicionais com valor maximo e minimo de rigidez baseado apenas no agregado. Os efeitos de segunda ordem sao avaliados com o coeficiente γz e do processo P-Delta, realizado com o software SAP2000. O modelo atribui menor resistencia e rigidez para o concreto nos pavimentos superiores, simulando uma pratica de projeto comum. Os resultados sao confrontados com modelo de referencia. Assim como ja consolidado, em primeira ordem a relacao entre modulo de elasticidade e deslocamento de topo...

Parâmetros de projeto de alvenaria estrutural com blocos de concreto, 2021

Esta é a segunda edição, revisada e ampliada, deste livro, que continua com a parceria entre a As... more Esta é a segunda edição, revisada e ampliada, deste livro, que continua com a parceria entre a Associação Brasileira de Cimento Portland (ABCP) e a Universidade Federal de São Carlos (UFSCar), que juntas desenvolvem projeto cujo objetivo é disponibilizar ao meio técnico um manual de melhores práticas para projeto de edifícios de alvenaria estrutural, com ênfase na utilização dos blocos de concreto. Após nove anos, esta nova edição está sendo finalizada em momento bastante oportuno, pois foi possível levar em conta a última atualização e unificação das principais normas brasileiras sobre o assunto que deram origem à recente norma ABNT NBR 16868 – Alvenaria Estrutural – Parte 1: Projeto; Parte 2: Execução e controle de obras; e Parte 3: Métodos de ensaio. Foram mantidos o formato e a sequência da edição anterior, porém o conteúdo deste livro sofreu uma revisão ampla do texto e exercícios para adaptá-lo às prescrições da norma ABNT NBR 16868:2020, da qual os autores tiveram ampla participação. As informações sobre detalhes e escolhas de projetistas com notoriedade em projetos de edifícios de alvenaria estrutural foram compiladas e melhoradas para o contexto atual em que o avanço de tecnologias e dos materiais permitiu a adoção de novas soluções no projeto e no processo construtivo. O livro continua condensando a experiência de renomados projetistas de edifícios em alvenaria estrutural, e espera-se que continue possibilitando que construtoras e engenheiros de obras tirem suas dúvidas e possam melhor discutir os detalhes com seus projetistas.

Materials and Structures, 2022

The fire behavior of a structural masonry building has a positive relationship with the behavior ... more The fire behavior of a structural masonry building has a positive relationship with the behavior of its constituent materials under high temperatures. Assessing the residual mechanical strength of the structural masonry components is essential, following the exposure to high temperatures. This work proposes to examine the standard for the determination of the mechanical properties (compressive strength and elastic modulus) of concrete blocks under high temperatures. Based on the existing recommendations (RILEM Technical Committee in Mater Struct 40: 841–853, 2007. 10.1617/s11527-007-9285-2, Mater Struct 40: 855–864, 2007. 10.1617/s11527-007-9286-1, Mater Struct 28: 410–414, 1995, Mater Struct 33: 219–223, 2000, Mater Struct 37: 139–144, 2004. 10.1007/bf02486610, Mater Struct 30: 17–21, 1997. 10.1007/bf02539270, Mater Struct 31: 290–295, 1998, Mater Struct 33: 6–13, 2000, Mater Struct 33: 224–228, 2000, Mater Struct 38: 913–919, 2005. 10.1617/14363RILEM Technical Committee (2007), Recommendation of RILEM TC 200-HTC in Mater Struct 40: 449–458, 2007. 10.1617/s11527-006-9203-z), an extensive experimental program was proposed to guide the adaptation of these recommendations to the case of concrete blocks, with emphasis on the heating and cooling rate of the samples. Suggestions of parameters necessary for laboratory evaluation of residual mechanical strength at elevated temperatures are presented for the hollow concrete block (HCB): number of specimens, testing age, storage conditions, rate of temperature rise with the time for heating the samples, suggestions of internal instrumentation of the equipment for the effective control of this rate and guaranteeing uniformity of heating.

International Journal of Masonry Research and Innovation, 2021

In Brazil, structural masonry is widely used in the construction of tall buildings. As the countr... more In Brazil, structural masonry is widely used in the construction of tall buildings. As the country does not have its own standard for masonry in a fire situation, the Fire Department recommends that the design of masonry structures in a fire situation be carried out in accordance with the instructions of Eurocode or similar international standard. This article critically analyses the adoption of design procedures in use in the USA, Australia and Europe for a typical Brazilian masonry structure, verifying the applicability of these codes and taking into account the differences in aggregates used in blocks and finishes, aiming to support discussions on Brazilian standardisation, in addition to comparing the different ways of approaching each standard. The results showed that it is possible to use international codes, but their use will not always portray the real situation, requiring the sector and the technical-scientific community urgently unite to address this issue.

In the last decades, several studies have been developed regarding structures composed by frames ... more In the last decades, several studies have been developed regarding structures composed by frames infilled with masonry walls, proving the increase of lateral stiffness by the infill. In this work, an analysis was carried out, based on design codes which adopt the equivalent diagonal strut method, to compare theoretical results with experimental ones of tests performed on steel frames infilled with concrete block masonry. Two of the three assessed codes specify lateral stiffness smaller than that measured from experimental testing, as safety measures for design. Regarding the masonry ultimate loads, the two specifications analyzed yielded similar values of critical force, although they pointed out different failure modes. The equivalent diagonal strut method has been proved to be a simple and useful tool for considering masonry walls and it should be used in case of reduced horizontal loads, prior to initial cracks of the infill wall.

Brick and Block Masonry - From Historical to Sustainable Masonry, 2020

In Brazil, one of the most used aggregates in the concrete blocks production is gneiss. There is ... more In Brazil, one of the most used aggregates in the concrete blocks production is gneiss. There is few information in literature about the behavior of concrete blocks with this type of aggregate at high temperatures. Besides that, the test procedures to determine the concrete stress-strain curve is generally prescribed for cylindrical cast specimens. The concrete's properties in this type samples are different from those produced in concrete block industries that use large vibrating presses with strong compaction energy and low cement consumption. This paper describes the effects of temperature on the mechanical properties of concrete blocks made with gneiss aggregate. For this, the CMUs were heated to 800°C and their residual compression strength and deformability was determined. The test method was adapted from the RILEM TC 200-HTC recommendations. In conclusion, the aggregate was thermally stable, and the residual compressive strength of the concrete block was basically unchanged below 400°C.

Construction and Building Materials, 2020

Abstract Flat-jack testing is considered efficient in the analysis of historical masonry built wi... more Abstract Flat-jack testing is considered efficient in the analysis of historical masonry built with stones or solid bricks. The advantage of this technique is obtaining important properties to a structural analysis, such as the stress-strain curve of the wall, masonry modulus of elasticity and an estimate compressive strength, without any permanent damage to the structure. Due to its advantages, the technique could also be applied in modern masonry, but the current available equipment has limitations in its geometry and maximum applied pressure. This paper presents the development and application of a new flat-jack equipment, that can fit hollow blocks and allow applying high pressures of more than 20 MPa, way more than the usual flat-jack limit of 5 to 7 MPa. The developed flat-jack was used to test hollow concrete-block masonry to evaluate masonry strength and elastic modulus values, that were compared to values obtained from destructive testing also performed. A good correlation on both results was observed. Based on the experimental results and using the Abaqus FEM package, a detailed micro modelling is presented considering the masonry units, mortar and their interfaces. The numerical model was able to successfully capture crack pattern and strain and stress distribution of the walls in good agreement with the experimental results. Both on the experimental and numerical analyses the testing procedure on where to clean the mortar joints, on the top-bottom of the tested area or also at the lateral vertical joint of the region, was assessed. Result indicate the success and validation of using flat-jack application in modern high-strength hollow block masonry, as far as we know for the first time, and point suggestions on were the cut the mortar joint before testing.

PARC Pesquisa em Arquitetura e Construção, 2018

O presente trabalho apresenta estudo sobre alvenaria estrutural construída dentro de pórticos em ... more O presente trabalho apresenta estudo sobre alvenaria estrutural construída dentro de pórticos em concreto pré-moldado dimensionada como parte do sistema de contraventamento das edificações, definindo esse tipo de elemento como Alvenaria Participante. São identificados os principais detalhes construtivos das paredes de alvenaria participante que influenciam o comportamento do pórtico pré-moldado frente às ações horizontais. No Brasil, a contribuição dessas paredes não é considerada no dimensionamento da estrutura devido à falta de informações e à sua complexidade, o que leva a projetos mais conservadores. Neste estudo, identifica-se os principais detalhes construtivos das paredes de alvenaria participante que influenciam no contraventamento das edificações. Também, são consideradas as variáveis e mecanismos que algumas das principais normas internacionais utilizam na análise de alvenaria participante em pórticos para a estabilidade das estruturas. Além de, realizar a comparação entre...

Anais do Workshop De Tecnologia De Processos E Sistemas Construtivos, 2017

No Brasil, tem-se observado o crescente uso de elementos pré-fabricados de concreto, nesse contex... more No Brasil, tem-se observado o crescente uso de elementos pré-fabricados de concreto, nesse contexto, encontram-se os painéis de parede dupla pré-moldados que são um sistema construtivo formado por duas placas de concreto de pequena espessura mantidas unidas através de armadura treliçada. A armação estrutural necessária para todo o painel é construída dentro do componente pré-fabricado e após a instalação dos painéis, o espaço entre as placas pode ou não ser preenchido com concreto misturado e despejado no local da obra; neste sentido, o painel de parede dupla é um componente semi pré-fabricado. Esses painéis de fato combinam as maiores vantagens da pré-fabricação com as de uma parede fabricada em moldes concretados na obra. O presente trabalho apresenta uma investigação exploratória realizada através de revisão bibliográfica na qual será descrito e verificado as indicações de desempenho dos painéis de parede dupla pré-moldado conforme a recém lançada norma ABNT NBR 16475:2017, analisando criticamente os aspectos abordados e as lacunas deixadas pela a mesma; tendo com isto, o intuito de contribuir com a sistematização e difusão do tema na comunidade da construção civil brasileira.

Anais do Workshop De Tecnologia De Processos E Sistemas Construtivos, 2017

13th North American Masonry Conference, 2019

Currently in Brazil different design and execution codes are valid for concrete block masonry and... more Currently in Brazil different design and execution codes are valid for concrete block masonry and clay block masonry. Since 2016 a technical committee is working on the draft of a unified code. The new code shall unify not only the procedures used to design with these materials but also will include execution and quality control. The new Brazilian Structural Masonry Standard will be divided into 5 parts: 1) design; 2) execution and quality control; 3) test methods; 4) design in fire situation; 5) seismic design. The proposals for Parts 1 to 3 have been finished and are discussed in this paper. Parts 4 and 5 are scheduled to be discussed between 2018 and 2022. In spite the committee has been based to several international codes, several aspects are unprecedented and take into account the boldness degree of Brazilian structural masonry, particularly related to building construction. The new version of part 1 maintains the consideration of the wall gross area reference for most of the design procedures and includes topics such as: specification for structural bricks, design of slender walls, use of lateral bracing for wall slenderness, special specification for one-story houses, a new method to design shear walls subjected to both vertical and in-plane or out-of-plane loads„ more accurate specification for concentrated load design, definition of the hollow block shape to consider full bond between grout and block, demand for third part structural design review, lateral stability specifications and limits, new specifications for beam design, new annex with specifications for lateral load design and wall infill design, recommendations for materials specifications (block, mortar, block strength combinations and resulting strengths of the prism assemblage). Part 2 brings completely new specification for quality control. Part 3 basically unifies the testing procedures and includes recommendation for removal of masonry specimens from existing construction.

13th North American Masonry Conference, 2019

Currently, in Brazil, the current structural masonry standards are divided into clay block struct... more Currently, in Brazil, the current structural masonry standards are divided into clay block structural masonry standards and concrete blocks structural masonry standards. The study committee ABNT / CE-002: 123.010 recently proposed the unification of these standards which is expected to be published this year. It is observed that, even with the unification of the standards, there are gaps regarding the fire behavior of structural masonry. Faced with this, this same commission of studies intends to launch in the next two years a code that meets this need. In Brazil, structural masonry is widely used in the construction of high-rise residential buildings, and it is important to be attentive to the building's ability to resist fire. Because of this, the Fire Department of the State of Sao Paulo recommends sizing the masonry structures in a fire situation according to the instructions of Eurocode 6 or a similar international standard. In this article, the adoption of structural fire masonry design procedures of the United States, Australia and Europe standards for a typical structure of Brazilian structural masonry is critically examined. The applicability of these codes to the Brazilian context, due to the differences in the materials of the blocks and finishing was verified, in order to subsidize future discussions on Brazilian standardization, as well as to compare the different approaches to each standard.

Esta é a segunda edição, revisada e ampliada, deste livro, que continua com a parceria entre a As... more Esta é a segunda edição, revisada e ampliada, deste livro, que continua com a parceria entre a Associação Brasileira de Cimento Portland (ABCP) e a Universidade Federal de São Carlos (UFSCar), que juntas desenvolvem projeto cujo objetivo é disponibilizar ao meio técnico um manual de melhores práticas para projeto de edifícios de alvenaria estrutural, com ênfase na utilização dos blocos de concreto. Após nove anos, esta nova edição está sendo finalizada em momento bastante oportuno, pois foi possível levar em conta a última atualização e unificação das principais normas brasileiras sobre o assunto que deram origem à recente norma ABNT NBR 16868 – Alvenaria Estrutural – Parte 1: Projeto; Parte 2: Execução e controle de obras; e Parte 3: Métodos de ensaio. Foram mantidos o formato e a sequência da edição anterior, porém o conteúdo deste livro sofreu uma revisão ampla do texto e exercícios para adaptá-lo às prescrições da norma ABNT NBR 16868:2020, da qual os autores tiveram ampla participação. As informações sobre detalhes e escolhas de projetistas com notoriedade em projetos de edifícios de alvenaria estrutural foram compiladas e melhoradas para o contexto atual em que o avanço de tecnologias e dos materiais permitiu a adoção de novas soluções no projeto e no processo construtivo. O livro continua condensando a experiência de renomados projetistas de edifícios em alvenaria estrutural, e espera-se que continue possibilitando que construtoras e engenheiros de obras tirem suas dúvidas e possam melhor discutir os detalhes com seus projetistas.