Dora Silveira

Structural Behaviour and Retrofitting of Adobe Masonry Buildings

Earth is one of the most widely used building materials in the World. Different types of adobe dwellings are made to assure protection and wellbeing of the population according to the diverse zones needs. Therefore, it is important to study the structural behaviour of the adobe masonry constructions, analysing their seismic vulnerability, which may help in preventing social, cultural and economic losses. In the present chapter, an explanation of the seismic behaviour of adobe buildings, a summary of recent research outputs from experimental tests conducted on adobe masonry components and from numerical modelling of full-scale representative adobe constructions are reported. In addition, different rehabilitation and strengthening solutions are presented and results from the testing of retrofitted adobe constructions and components are discussed.

Mechanical Properties and Behavior of Traditional Adobe Wall Panels of the Aveiro District

AbstractIn the Aveiro district, Portugal, adobe was a construction material extensively used until the middle of the twentieth century. Presently, many adobe constructions are still in use, presenting important cultural, social, and architectural value. Many of these constructions, however, are in a poor state of conservation, displaying severe structural anomalies. This negligence is in part due to a lack of knowledge concerning the mechanical behavior and properties of adobe masonry. The purpose of this paper is to contribute to this knowledge. Ten full-scale adobe wall panels were constructed in the laboratory with adobes collected from an existing construction and with mortar formulated with the composition traditionally used. Five wall panels were tested in simple compression and five wall panels in diagonal compression. From these tests it was possible to determine and evaluate the stress-strain relationships, strength, deformation, stiffness, and damage pattern of the adobe masonry walls. This know...

Rehabilitation of an important cultural and architectural heritage: the traditional adobe constructions in Aveiro district

Adobe is a low-cost construction material, locally available, presents excellent thermal and acoustic properties, and is associated to quite simple construction methods that only require a small consumption of energy. It is indeed an economically viable material, and its use respects the environmental equilibrium. Rehabilitation and strengthening of existing traditional adobe constructions contribute to the quality of life improvement of those who use them and for an increase of associated safety levels, particularly if an effective seismic strengthening is assured. The preservation of these constructions also contributes for the recognition of the advantages that adobe, as a structural material, presents, encouraging its use in new constructions, and allowing for the reduction of the efforts and resources that are affected to new edifications that normally replace the adobe existing ones. A research group at the University of Aveiro has been developing work aimed at the characterization of the vast traditional adobe constructed park of Aveiro district, which constitutes an important architectonic and cultural heritage. Studies on the composition and mechanical behaviour of adobe units and mortars, and on the structural behaviour of adobe masonry walls were conducted. These studies aim to establish a basis of knowledge that can support the interpretation of structural pathologies, calibration of numerical models, structural safety assessment, and design of strengthening solutions. This article presents and discusses the developed work, explaining how it can contribute for

Seismic behavior of two Portuguese adobe buildings: Part I - in-plane cyclic testing of a full-scale adobe wall

ABSTRACT This article addresses the laboratory testing of a full-scale double-T shaped adobe wall, under in-plane horizontal cyclic loading of increasing amplitude, with the aim of contributing to the understanding of the seismic behavior of adobe structures. The wall was built with lime adobes taken from an existing building and mortar with a traditional composition. The behavior of the wall was assessed in terms of: shear stress versus horizontal drift and moment versus rotation relationships; maximum lateral strength; drift and rotation at peak stress; evolution of stiffness, lateral displacements, dissipated energy, and natural frequency; and damage pattern. The wall exhibited brittle behavior and in-plane strength corresponding to 56% of the vertical load. Cracking was observed with an X-shaped pattern whereas no sliding occurred at its base. This research supported the subsequent development of a repair and retrofit solution and also of numerical models to simulate the seismic behavior of two adobe buildings.

Seismic behavior of two Portuguese adobe buildings: part II —numerical modeling and fragility assessment

ABSTRACT Considering the likely unfavorable behavior under seismic action of adobe construction, this article aims at providing a seismic fragility characterization of two adobe Portuguese traditional buildings, using numerical models calibrated over experimental results. The study of such two case-study buildings in the region of Aveiro contributes to the understanding of the seismic fragility of adobe construction in the region in general. The buildings were numerically modeled to estimate their structural behavior under seismic loading using adobe material properties that were calibrated based on the experimental results of a cyclic in-plane test of a full-scale double-Tshaped adobe wall. The method chosen to characterize adobe masonry and model its nonlinear behavior followed a total strain crack-based macro-modeling (TSCM) approach, whereas pushover analysis was carried out to reproduce the pseudo-static experimental test in order to enable a refined calibration of adobe masonry mechanical properties. Fragility functions were then derived, based on the above-mentioned numerical models, using nonlinear static analysis, bringing further insight on the seismic fragility of traditional Portuguese adobe construction.

Survey of the facade walls of existing adobe buildings

ABSTRACT Adobe construction was very common in Aveiro district, Portugal, until the middle of the 20th century. At present, there are still many adobe buildings in use, a significant percentage of which have social, cultural, and architectural value. Many of these buildings, however, are in a poor state of conservation. The existing problems are partially the result of a lack of knowledge about the materials and building systems traditionally used. To contribute to this knowledge, a visual and dimensional inspection of the facade walls of twenty one adobe buildings located in Anadia, Murtosa, and Aveiro municipalities, in Aveiro district, was conducted. This article presents a description and analysis of the construction details, common defects, and state of conservation of the facade walls studied. This work aims to contribute with preliminary information that may help support the preservation and rehabilitation of existing adobe buildings.

LEVANTAMENTO E CARACTERIZAÇÃO DO PARQUE EDIFICADO EM ADOBE NA CIDADE DE AVEIRO

Ate meados do seculo XX, o adobe foi um material de construcao muito utilizado no distrito de Aveiro, em Portugal. Actualmente, nesta regiao, e em particular na cidade de Aveiro, permanecem ainda muitos exemplos de edificios construidos em adobe, alguns de importante valor patrimonial e arquitectonico. No entanto, muitos destes edificios tem sido votados ao abandono nas ultimas decadas, especialmente pela escassez de conhecimento tecnico para suporte a sua reabilitacao e reforco. Reconhecendo-se esta necessidade de conhecimento, nos ultimos anos comecou a desenvolver-se trabalho de investigacao nesse sentido. Neste artigo apresenta-se um trabalho de levantamento desenvolvido com o objectivo de caracterizar a distribuicao e as caracteristicas principais da edificacao em adobe existente na cidade de Aveiro. Descreve-se, de forma sucinta, a metodologia adoptada, bem como os resultados obtidos. O conhecimento adquirido permitira uma posterior seleccao de edificios representativos, para uma caracterizacao detalhada dos sistemas construtivos e das patologias mais comuns.

Seismic Retrofit of Adobe Constructions

Earthen construction has been widely used since ancient times. Currently, this type of construction is used by approximately one third of the world population. In comparison to other, more modern building materials, such as brick masonry, reinforced concrete, and steel, earth is costless and primarily accessible. For these reasons, it is massively used by no-income or low-income families, in developing countries and in communities where the mentioned industrial materials were never incorporated, frequently without adequate attention being paid to structural safety and reinforcement issues. Moreover, buildings are generally constructed and rehabilitated by non-specialized staff, with empirical knowledge passed through generations, lacking information and understanding of their structural behaviour. The seismic behaviour of earthen structures is typically characterized by fragile and sudden failure, because earth is a brittle material with very low tensile strength. Thus, earthen constructions and, in particular, adobe constructions, if not adequately designed and strengthened may perform very poorly when subjected to seismic loads. There are, in fact, various examples of recent earthquakes that caused severe damage to earthen buildings. The study of the structural behaviour of earthen constructions and the development of effective strengthening solutions are fundamental. In the present chapter, an introduction to earthen construction, including a brief description of its use throughout the world and main vulnerabilities, is presented. The structural behaviour of adobe construction is explained, in particular when subjected to seismic demands. Different repair and strengthening solutions are presented, together with various experimental studies conducted by different authors. A short review of the existing standards and codes that address the seismic design of earthen buildings is also presented. Finally, a brief reference is made to the numerical modelling of adobe construction.