Earthen construction: structural vulnerabilities and retrofit solutions for seismic actions

Earthen structures present very appealing characteristics regarding a more sustainable practice with the preservation of our natural resources. However, when subjected to earthquake ground motions, this type of construction may present a deficient performance, which may cause significant human losses and important structural damage. The seismic response of earthen structures is typically characterized by fragile failures. There are several examples of recent earthquakes that affected earthen buildings in a severe way, evidencing the vulnerability of this type of construction, like the El Salvador earthquake, in 2001, the Bam, Iran earthquake, in 2003, the Pisco, Peru earthquake, in 2007 and the Maule, Chile earthquake, in 2010. The construction of earth structures on earthquake-prone areas must be carefully studied and should include seismic reinforcement solutions in order to improve their seismic performance. In this paper, the performance of earthen structures in recent earthquakes will be examined, analyzing failure modes inherent to these particular construction materials and associated construction techniques. Also, seismic reinforcement approaches and techniques will be presented in a comprehensive manner. Examples of tests conducted for the assessment of retrofitting solutions efficiency will be presented, and the results obtained will be discussed

Materials and techniques of Art Nouveau architecture in Italy and Portugal: a first insight for an European route to consistent restoration

The results of the investigations on building materials and techniques of Casa Major Pessoa, a typical Art Nouveau construction in Aveiro (Portugal), and two coeval Art Nouveau buildings in Bologna (Italy) are presented as a methodological contribution to the restoration of this kind of buildings. This is the first step to ascertain the existence of a common thread between local materials, technologies and architecture in European countries at the same period. A holistic approach was adopted: materials were investigated along with architectural, structural and technological features, in order to achieve a first insight into the Art Nouveau architecture in Europe in particular for its consistent restoration without loss of historical memory

On the Evaluation of the Mechanical Behaviour of Structural Glass Elements

Glass can be considered to be a high-technology engineering material with a multifunctional potential for structural applications. However, the conventional approach to the use of glass is often based only on its properties of transparency and isolation. It is thus highly appropriate and necessary to study the mechanical behaviour of this material and to develop adequate methods and models leading to its characterisation. It is evident that the great potential of growth for structural glass applications is an important opportunity of development for the glass industry and the building/construction sectors. The work presented in this paper is a reflection of this conclusion. The authors shortly present the state-of-the-art on the application of glass as a structural element in building and construction, and refer to other potential fields of application and available glass materials. The experimental procedures and methods adopted in three-point bending tests performed on 500 × 100 [mm2] float, laminated and tempered glass specimens with thicknesses between 4 and 19 mm are thoroughly described. The authors evaluated the mechanical strength and stiffness of glass for structural applications. This work contributes to a deeper knowledge of the properties of this material

Inspection and diagnosis tests for structural safety evaluation: A case study

Diagnosis and assessment of existing structures is a developing area due to the appearance of a high number of building defects, structural and non-structural deterioration and precocious loss of quality, and, consequently, lower expected durability. With the aim of verifying the viability of rehabilitation or the need to demolish an existing fifteen year old parking building, several inspections and diagnostic non-destructive and destructive testing, visual inspection, were carried out to evaluate the structural safety conditions

Reflexões sobre erros frequentes na concepção e execução de moradias unifamiliares: casos de estudo

A deficiente concepção, a não aplicação das boas práticas construtivas, a negligência e ausência de acompanhamento na construção de moradias unifamiliares tem reflexo directo no aparecimento de várias anomalias. Este artigo apresenta e analisa patologias e defeitos de construção de três habitações unifamiliares, frequentemente observados em outros casos de estudo, suas causas e consequências, discutindo ainda outros factores como os custos de reparação, as obrigações e responsabilidades dos intervenientes.The faulty conception, disrespect of good constructive practices, neglection and absence of accompaniment of the small and medium constructions is evident that lead to the appearance of several defects. This article presents and analyzes the pathologies and construction defects in three house dwellings, frequently observed in cases of study, its causes and consequences, still discussing other factors such as the repair costs, the obligations and responsibilities of the intervenients

Frequency and damping evolution during experimental seismic response of civil engineering structures

The results of the seismic tests on several reinforced-concrete shear walls and a four-storey frame are analysed in this paper. Each specimen was submitted to the action of a horizontal accelerogram, with successive growing amplitudes, using the pseudodynamic method. An analysis of the results allows knowing the evolution of the eigen frequency and damping ratio during the earthquakes thanks to an identification method working in the time domain. The method is formulated as a spatial model in which the stiffness and damping matrices are directly identified from the experimental displacements, velocities and restoring forces. The obtained matrices are then combined with the theoretical mass in order to obtain the eigen frequencies, damping ratios and modes. Those parameters have a great relevance for the design of this type of structures

Avaliação da segurança sísmica de pontes e reforço com FRP´s

A avaliação da segurança e a conservação das pontes têm vindo a suscitar interesse crescente nos últimos anos. O reforço destas estruturas para a acção sísmica é importante, uma vez que são infra-estruturas fundamentais para a intervenção das equipas de socorro em acções pós-sismo, mas também pelas consequências económicas e sociais associadas a eventuais danos severos ou colapso destas obras. O reforço sísmico passa pela aplicação de sistemas que permitam atenuar e controlar os efeitos produzidos pelas acções dos sismos. Actualmente, com o aparecimento de nova regulamentação, como os Eurocódigos e outras guidelines, e de novos materiais como os polímeros reforçados com fibras (FRP – Fiber Reinforced Polymer), o reforço de pontes existentes é mais viável, tecnicamente e economicamente. As vantagens da utilização de sistemas de FRP’s na reabilitação e reforço de pontes resultam das suas propriedades mecânicas, dado que possuem elevada resistência mecânica, reduzido peso dos materiais e elevada resistência à corrosão, aliada à facilidade de aplicação e à disponibilidade de uma grande diversidade de sistemas de FRP’s no mercado. Neste trabalho procedeu-se à análise de um viaduto corrente existente, simulandose, com recurso a um modelo numérico, o seu comportamento estrutural, identificando e localizando as zonas críticas. Com base nos resultados da avaliação, estudou-se e propôs-se uma solução de reforço sísmico com base nas indicações do Boletim FIB 14, e de acordo com a filosofia adoptada pelos Eurocódigos. Desse modo, procedeuse à recolha de informação relativa à obra de arte em estudo e à simulação numérica da estrutura. Inicialmente procedeu-se à calibração do modelo numérico com recurso a medições das suas frequências fundamentais. De seguida, desenvolveu-se a verificação da segurança estrutural ao nível dos elementos. E, por fim desenvolveu-se uma proposta de reforço sísmico com recurso a sistemas de FRP’s de modo a garantir a capacidade exigida aos elementos onde a segurança não foi verificada para a acção sísmica

Out-of-plane in situ cyclic testing of unreinforced stone masonry walls with distributed loads

The present paper reports an in situ experimental test campaign carried out on existing buildings, in order to investigate the seismic behaviour of traditional masonry walls subject to out-of-plane loads. For the testing proposes, an experimental test setup based on a selfequilibrated scheme was developed and optimized to be applied in situ in two specimens on original and strengthened conditions. The obtained results are presented and carefully discussed namely from the reinforcement solutions’ efficiency point-of-view, as well as compared to previous experimental data obtained for the same type of masonry walls. Additionally, a simplified linearized displacement-based procedure was adapted in order to characterize the nonlinear force-displacement relationship for unreinforced traditional masonry walls and to analytically predict the experimental test results. The confrontation between the experimental and the analytical results are presented and discussed

Reforço de edifícios existentes de betão armado com contraventamentos metálicos

Foi calibrado um modelo numérico refinado para a reprodução do comportamento de estruturas existentes de betão armado, e do seu reforço por contraventamento, face a solicitações sísmicas. Estes modelos foram calibrados com base numa série de ensaios

I materiali dell’ Arte Nova portoghese in Casa Major Pessoa ad Aveiro: caratterizzazione e confronto con edifici coevi in Bologna

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