Browsing by Author "Henriques, Dulce Franco"
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- Assessment of a timber structure in the “Ermida da Ascensão de Cristo” in LisbonPublication . Araújo, Diana; Henriques, Dulce FrancoThis paper presents the assessment of a timber structure in service and the aspects that should be consider for its proper development. To assess wooden structures is necessary to know not only the material and its characteristics but also the degradation agents to what can be subject and the appropriate inspection and diagnosis techniques for each case. The case presented in this work is the last floor structure of the "Ermida da Ascensão de Cristo", situated in Bairro Alto, Lisbon, Portugal. An inspection plan to the structure was followed which included several techniques of assessment namely visual inspection, moisture content determination and the use of semi-destructive devices to know the drill resistance and the penetration resistance of the wood. The use of traditional and non-traditional methods allowed the conjugation of information and obtaining results. A survey of the existent normalization was realized which allows the grading of the timber, in both qualitative and quantitative terms: grades and strength classes. The Portuguese standard NP 4305:1995 was followed in the measurement and assessment of only three grading rules: knots, slope of grain and rate of growth. The extension of the damage suffered by the structure due to the attack of wood boring insects was also evaluated, and was determined the loss of section. By the standard EN 338:2009, the characteristic values were determined, which, following the methodology of standard EN 1995:2004, allowed the evaluation of the structure behaviour to bending, deformation and shear. The use of standard NP 4305:1995 in a simplified way allows its adaptation to a timber structure in service, characterization and assessment in order to be able to determine solutions to its rehabilitation.
- Avaliação local da capacidade mecânica de elementos de madeira em edifícios antigosPublication . Neves, André; Henriques, Dulce FrancoA manutenção e a reabilitação da madeira como material de construção dos edifícios antigos conduz necessariamente à sustentabilidade do património edificado. Além disso, reabilitar permite ainda conservar o valor histórico e artístico dos edifícios, um bem não recuperável. É neste sentido que importa avaliar o estado de integridade e capacidade mecânica da madeira existente nos edifícios e proceder à sua conservação / consolidação / reforço, em função do uso futuro do edifício, dando especial importância às palavras – Reduzir, Reutilizar e Reciclar. É necessário, portanto, encontrar formas de reconhecimento de características mecânicas da madeira em uso. O texto apresenta um estudo de correlação entre a resistência mecânica da madeira antiga de Casquinha, Pinus sylvestris L., obtida em laboratório por ensaios destrutivos e não destrutivos, com a mesma obtida in situ por ensaios não destrutivos. Através dos equipamentos Resistograph® e Pilodyn®, pretende-se estimar a capacidade mecânica local da madeira em uso, baseada nas correlações encontradas laboratorialmente para propriedades de referência da madeira, apresentando-se para o efeito um caso de estudo. Apesar da grande variabilidade de resultados obtidos, foi possível encontrar uma linha coerente de valores de propriedades para os elementos de madeira analisados.
- CoberturasPublication . Freitas, Vasco Peixoto de; Miranda, Andreia Mota; Henriques, Dulce FrancoEm edifícios antigos, a cobertura mais comum é do tipo inclinado com estrutura de madeira [a]. Em edifícios recentes, a maioria das estruturas é em betão armado ou em elementos pré-fabricados de betão pré-esforçado (inclinadas ou em terraço) e/ou ainda em elementos metálicos. O revestimento superior é de telha cerâmica ou de betão, registando-se porém muitas outras soluções.
- Consolidating preservative-treated wood: Combined mechanical performance of boron and polymeric products in wood degraded by Coniophora puteanaPublication . Henriques, Dulce Franco; Brito, Jorge Manuel Caliço Lopes de; Duarte, Sónia; Nunes, LinaWhen timber elements in heritage buildings are moderately degraded by fungi and assuming underlying moisture problems have been solved, two actions can be taken: i) use a biocide to stop fungal activity; ii) consolidate the degraded elements so that the timber keeps on fulfilling its structural and decorative functions. The aim of this work is to investigate the mechanical performance of maritime pine wood degraded by fungi after being treated with a biocide followed by impregnation with a polymer product. Three commercially available products were used: a boron water-based biocide, an acrylic consolidant and an epoxy-based consolidant. Treated and consolidated specimens were subjected to mechanical tests: axial compression test (NP 618), static surface hardness (ISO 3350) and bending test (NP 619). Sets of replicates were subjected to an evaporation ageing test (EN 73) after application of the products and also tested for mechanical behaviour. An increase in mechanical strength was observed for both consolidants with no significant influence from the previous use of biocide product. The specimens subjected to ageing showed a slightly better general mechanical performance.
- Diagnóstico de estruturas de madeira em serviço num palacete do século XIXPublication . Cândido, Ana; Henriques, Dulce FrancoNo presente artigo são apresentadas e aplicadas metodologias de avaliação não destrutivas de elementos estruturais de madeira em serviço em edifícios antigos. Em Portugal existem muitos edifícios com elevado valor patrimonial, cuja estrutura é constituída em grande parte por elementos de madeira. Desta forma, para garantir a sua manutenção e conservação é fundamental aplicar técnicas comprovadas de inspecção e diagnóstico, a fim de ser possível o reconhecimento do seu estado e características reais. O caso de estudo que serve de base ao presente artigo é o Palacete Ribeiro da Cunha, construído em 1877, no centro de Lisboa. Ao longo do trabalho procedeu-se à inspecção e diagnóstico de três zonas do edifício: pavimento, cobertura dos arrumos e cobertura do lanternim. Cada local foi sujeito a um rigoroso plano de inspecção, recorrendo-se a métodos visuais e a ensaios não destrutivos com Resistógrafo, nos casos em que o elemento apresentava degradação biológica. Os elementos de madeira foram classificados visualmente pela aplicação das normas NP 4305:1995 - Madeira serrada de Pinheiro bravo para estruturas - Classificação visual [1] e UNI 11119:2004 - Load-bearing structures - On site inspections for the diagnosis of timber members [2]. O Eurocódigo 5 (EN 1995:2004 - Design of timber structures [3]) também é abordado na perspectiva de verificação de segurança tendo em conta o nível de degradação registado. A utilização de ensaios não destrutivos verificou-se vantajosa, não só por facilitar a compreensão e obtenção de propriedades mecânicas e resistentes da madeira, mas também pelo seu carácter pouco intrusivo dado que se trata de um edifício com enorme interesse e valor arquitectónico. Este estudo constitui uma parte de um relatório de inspecção e diagnóstico, que serve de base a tomadas de decisão sobre as acções a empreender, como sejam a implementação de medidas preventivas ou de tratamento ou então a aplicação de técnicas de reforço e reabilitação. This paper presents and applies a non-destructive evaluation method of wood structural elements in service in old buildings. Many buildings, with significant historical value, are located in Portuguese old towns. In most cases they have timber structures which need specific care to keep, at least, reasonable levels of conservation and security. Thus, the research and development of more efficient inspection and diagnosis methods are essential to verify the needs of rehabilitation. The case study is a palace located in a major historical area of Lisbon, named Palacete Ribeiro da Cunha. Its construction dates from 1877, thus being an important part of local heritage. Three different áreas of the timber structure were subject to a thorough inspection plan using visual inspection and nondestructive testing with Resistograph, where the elements were biological degraded. The wooden elements were visually classified by applying the NP 4305 standards: 1995 - Maritime pine for structures – visual classification [1] and UNI 11119: 2004 - Load-bearing structures – On site inspections for the diagnosis of timber members [2]. Eurocode 5 (EN 1995: 2004 - Design of timber structures [3]) is also addressed, in order to verify if the safety conditions are satisfied, despite the observed damage level. The visual inspection revealed itself very useful, supporting testing results. This study is part of an inspection and diagnostic report, which provides the basis for decision-making on actions to be taken, such as the implementation of preventive measures or treatment or the application of strengthening and rehabilitation techniques.
- Estimation of timber members properties combining direct and indirect information: two applicationsPublication . Henriques, Dulce Franco; Cândido, A.In conservation or rehabilitation works of ancient buildings serious doubts are often raised about the real condition of its structural timber members. Improving the practical knowledge upon visual and local recognition of the members in service and their connections is therefore of huge importance. This subject is nowadays under discussion and international com- mittees (RILEM, COST E55, COST IE0601, COST FP1101) have recently promoted some guid- ance documents to support actions to assess the structural condition of timber members. This research presents two practical situations. The assessment of two pine wood structural ele- ments included in historic buildings located in the center of Lisbon city: a timber floor and a tim- ber roof truss. These structural elements, composed for several timber members were submitted to: i) visual strength grading according to national and international standards; ii) semi- destructive testing; iii) safety assessment. Methodologies for property estimation of timber mem- bers in service are applied and their results discussed. Through the development of this study it became clear the importance of visual inspection for this kind of cultural heritage buildings. The use of a visual strength grade standard specific for timber members in service is also very important. In this case, the standard used accepted four beams that would have been replaced if only other methods had been used. On the other hand, the closer estimation of the density of the elements leads to a more real safety assessment. This study gains great relevance in the current reality in which the industry of building rehabilitation is on the rise but is not always accompanied by the necessary technical knowledge of the technicians involved and often leads to the removal of timber structural members in perfect physical and mechanical conditions..
- Inspection and diagnosis of timber structures by non-destructive methodsPublication . Cândido, Ana; Henriques, Dulce FrancoMany buildings with significant historical value are located in Portuguese old towns. In most cases these types of buildings have timber structures which need specific care to keep, at least, reasonable levels of conservation and safety. Thus, research and development of more efficient inspection and diagnosis methods are essential to verify the needs of rehabilitation. The building studied is a palace named Ribeiro da Cunha located in a major historical área of Lisbon, Portugal. Its construction dates from 1877, thus being an important part of local heritage. The main objective of this study is the application of non-destructive tests in timber structure elements. To achieve this, three different areas of the timber structure were subjected to a thorough inspection plan, which included visual inspection and non-destructive testing. The biological wood degradation was also under analysis, through the identification of beetles, subterranean termites and fungi. The visual inspection proved very useful, supporting testing results for the assessment of timber structures. Nowadays, visual grading of timber structures is subject to regulation in many countries. Thus, the employment of some of these standards, and further explanation of the difficulties and limitations related with their application on-site, is one of the objectives of this study. In addition, Eurocode 5 (EN 1995:2004) is also addressed, in order to verify whether the safety conditions are satisfied, despite the observed damage level. The choice of non-destructive tests have proven useful, not only because it allows for a better mechanical characterization, but also because of its careful approach resulting in no damage, much needed in buildings with such architectural value. Therefore, this study can be useful in an initial inspection and diagnosis phase of the building`s timber structure elements rehabilitation needs.
- Madeira em edifícios antigos: conservar, reforçar ou substituir?Publication . Henriques, Dulce FrancoA madeira afirmou-se ao longo dos séculos como um material estrutural confiável, suportando ainda hoje grande das estruturas das construções antigas que permanecem, dando vida aos centros históricos das nossas cidades. A preservação destes edifícios e das suas técnicas e materiais tradicionais é uma obrigação que devemos assumir perante as próximas gerações. Para que uma intervenção seja realizada preservando a maior quantidade possível de material estrutural histórico, é necessário que a avaliação do estado de conservação, bem como da segurança estrutural, seja realizada com base em informações credíveis e em procedimentos de avaliação confiáveis e aceites. O presente artigo pretende refletir sobre a viabilidade de manter os elementos em madeira nos edifícios antigos correntes, face à opção, muitas vezes tomada, da sua substituição integral. Apresenta técnicas práticas de reconhecimento do estado de degradação e os processos de avaliação da segurança de acordo com as mais recentes diretrizes internacionais. Faz também uma reflexão sobre a situação em que se apresentam atualmente os edifícios antigos e apresenta técnicas pouco intrusivas que se poderão aplicar em obra, mantendo sempre que possível os elementos estruturais antigos.
- Mechanical evaluation of timber conservation processes by bending testsPublication . Henriques, Dulce Franco; Nunes, Lina; Brito, Jorge deThis paper presents the laboratory work performed with the purpose of understanding the mechanical performance of 340x20x20 mm maritime pine wood samples degraded by rot fungi when treated with a biocide product followed by consolidation through impregnation with a polymeric product. Four commercially available products were used: a water-based biocide, BC, a solvent-based biocide, X, an acrylic consolidant, PB (PB 72), and an epoxy-based consolidant, E. Seven sets of specimens each one having a varied range of fungal degradation were prepared. Then the product combinations were applied by brush to six sets of specimens (E, X-E, BC-E, PB, X-PB, BC-PB) of which one was left untreated for control, 0-0. Finally all sets were subjected to static bending strength test until rupture. Results showed that the acrylic and epoxy-based products lead to increased mechanical capacity of the consolidated wood up to 100% in some cases in specimens with 70% of MOE loss. The results presented the same order of magnitude for both wood consolidants. The previous application of biocide did not have a significant impact in the behavioral pattern of the consolidant: a marked improvement of the bending strength of the degraded specimens after treatment and consolidation. These results demonstrated the feasibility of combining biocide/consolidation products, and provide indications of interest to the application of this technique to extend the lifespan of wood elements moderately degraded by fungi in old buildings.
- Outodoor wood weathering and protectionPublication . Henriques, Dulce Franco; Azevedo, Ana Cristina BorgesThis paper deals with the wood durability when applied in the building façades and outdoor subject to aggressive environmental agents and its means of protection. This study is justified since wood outdoors is na important part of the built heritage that needs to be preserved. The aim of this work was to obtain the relationship between the performance of wood surface protection products and different service situations. It was evaluated its coating ability to the environmental aggressions, simulating an application above ground and exposed to the weather (use class 3.2 - EN 335-2:2013) and to the attack by fungi simulating an application in direct contact with soil (use class 4.1). The long-term goal of this work is to contribute for the creation of a results network making easier for the user to protect wood from external aggression. Four different environmental conditions were chosen: next to the coast (saline); urban centre (pollution); interior of the country (high thermal amplitude); soil contact (fungi and moulds) and building interiors (control). Three commercial water based products were chosen due to its characteristics: WRN - water resistance assured by nanotechnology; WAC – weatherproof acrylic copolymer; ART - acrylic resins with Teflon®. This work showed that the most aggressive environment was the one with high thermal amplitudes. Comparing the performance of tested products: WRN exhibits the lowest protection levels, only antifungal function was comparable to the other products, in this formulation instead of sealing the pores, nanoparticles "dress them", assuring that water is effectively repelled by chemical forces; WAC and ART were very similar since both form a protective film increasing the surface resistance; ART presents the best performance with respect to coating integrity with very positive influence against the development of cracks.