Assessment of the seismic behaviour of unreinforced: traditional half-timbered walls

Half-timbered buildings represent an important historical heritage in many countries. They are diffused in various regions for different reasons, among which for being able to resist seismic actions. Despite the great popularity of this kind of structures, few studies are available on their global behaviour or on that of their single structural elements. The aim of this paper is to study the behaviour under cyclic loading of traditional half-timbered walls, with connections, materials and elements dimensions encountered in existing buildings. Cyclic tests have been performed in order to evaluate the performance of distinct traditional retrofitting techniques of the connections, namely: (1) increasing the number of nails at the connection; (2) use of steel bolts; (3) use of steel plates. The idea is to compare the performance in terms of hysteresis loops and the assessment of the improvements of the cyclic response in terms of ductility and energy dissipation

Seismic performance of traditional half-timbered walls : experimental results

Half-timbered structures constitute an important cultural heritage of many countries, since they represent a typical anti-seismic construction adopted worldwide [1][2]; therefore, their preservation is of the utmost importance. Although recent earthquakes have pointed out the good seismic behaviour of this kind of structures, few experimental studies are available on the performance of traditional half-timbered walls and their retrofitting solutions and mainly only qualitative information is available of the seismic response of such structures. Due to this lack of information, an extensive experimental campaign was carried out, performing in-plane cyclic tests on real scale half-timbered and timber frame walls, adopting connections and dimensions encountered in real structures and considering different infill types (brick masonry and lath and plaster). Moreover, keeping in mind the great rehabilitation effort that has been carried out in recent years on such buildings, such in the case of the Portuguese Pombalino buildings in Lisbon, it is important to study the effect of strengthening on traditional timber-frame walls. To do this, retrofitting solutions have been applied to traditional walls and tested under cyclic loading. Both traditional and innovative techniques have been considered, namely bolts, steel plates and NSM steel flat bars. Results on the behaviour of both unreinforced and retrofitted walls are analysed and their seismic behaviour is discussed.Fundação para a Ciência e a Tecnologia (FCT

The design and performance of high-performance perforated fired masonry bricks

Fire perforated clay masonry units have been extensively used through years in masonry structures, particularly in masonry walls both for loadbearing and non-loadbearing purposes (partition walls and enclosures). The location of the masonry walls as external enclosure brings some physical requirements, which together with mechanical requirements are the basis of the design of hollow clay bricks. This chapter provides an overview of the design requirements and design concepts of hollow clay bricks, together with some recent trends arising in the framework of obtaining more sustainable constructive materials. It discusses the main issues related to the mechanical performance of the units and of the masonry assemblages under distinct loading conditions. As often the unreinforced hollow clay masonry is built in seismic prone regions, an emphasis is given to the seismic behavior of hollow clay brick masonry under combined vertical and lateral in-plane loading, being discussed the main seismic performance parameters

Evaluation of the in-plane seismic performance of stone masonry walls

Although traditional historic masonry walls can be viewed as unsuitable structures to undergo seismic actions, they, in fact, exist and frequently represent the major structural elements of ancient buildings. Brick unreinforced masonry walls have been widely studied both from experimental and numerical point of view, but scarce experimental information is available for stone masonry walls. Therefore, the present work aims at increasing the insight about the behavior of typical ancient masonry walls under cyclic loading. Besides the strength and stiffness characterization, information about nonlinear deformation capacity is provided in terms of ductility factor and lateral drifts, which represent a step forward for the new concepts of performance based design

Modern masonry structures and earthquakes : reinforced or unreinforced?

The evolution of structural masonry is briefly reviewed, from old thrust line behavior to modern global behavior using shear walls. For modern structural masonry, the use of unreinforced, confined and reinforced masonry is addressed in seismic areas. A first focus is given to recent approaches towards the safety assessment of unreinforced masonry buildings and their performance in shaking table tests. Subsequently, building systems for modern masonry structures recently developed and tested at University of Minho are presented, one based on lightweight concrete blocks and another based on normal concrete blocks. The experimental and numerical work carried out is discussed and conclusions on the performance of the systems are given

Análise experimental do comportamento de paredes de alvenaria de pedra não reforçada sob acções cíclicas no plano

Com o presente trabalho pretende-se efectuar a avaliação experimental do comportamento de paredes de alvenaria de pedra não reforçada, com diferente aparelho das pedras em alçado, submetidas a acções horizontais cíclicas no plano. A análise dos resultados experimentais abrange a caracterização dos mecanismos de rotura, padrões de fendilhação, e a determinação da resistência última das paredes a acções horizontais cíclicas. Adicionalmente, realiza-se a discussão da resposta em termos de diagramas força-deslocamento, bem como o estudo comparativo da resistência e rigidez lateral para os dois tipos de paredes ensaiadas.Empresa Augusto Ferreira. Bettor MBT

Assessment of the in-plane shear strength of stone masonry walls by simplified models

The present work intends to represent a further step in the knowledge of ancient stone masonry walls through an experimental approach, from which only few information is available. The main results of an experimental program based on in-plane static cyclic tests conduct on masonry wall panels with distinct masonry bond are presented. It is also revealed that simplified models, often used to predict the lateral shear strength of brick masonry walls submitted to static in-plane lateral loading, are also valid for stone masonry walls. Besides, the prediction of the lateral strength by means of a novel equilibrium model is also pointed out

An overview of seismic strengthening techniques traditionally applied in vernacular architecture

Specific architectural elements can be identified in vernacular constructions located in regions frequently exposed to earthquakes. Such elements are the result of a seismic culture which has been empirically developed during centuries so that the vulnerability of the buildings is reduced. This research is based on the fact that vernacular architecture may bear important lessons on hazard mitigation. Traditional earthquake resistant technologies can be successfully applied to preserve and retrofit surviving examples without prejudice for its identity. Few papers have focused on strengthening solutions emerging from vernacular architectural heritage. Research is particularly focused on case studies in Portugal where traces of Local Seismic Culture have been identified and documented through direct visual inspection, published information and local narratives. The main goal of this study is the identification and understanding of traditional construction solutions and detailing that, in many cases, have shown to improve the seismic performance of vernacular constructions.Fundação para a Ciência e a Tecnologia (FCT

Análise do contributo dos sistemas construtivos em alvenaria estrutural para a sustentabilidade dos edifícios

A indústria da construção tem um forte contributo para os efeitos negativos provocados sobre o meio ambiente, assim como a nível social e económico. Hoje em dia, a construção continua refém dos métodos construtivos mais tradicionais havendo uma forte resistência à introdução de novas tecnologias, mesmo que estas proporcionem um melhor desempenho ambiental das cidades e da qualidade de vida dos seus cidadãos.  Deste modo, o estudo e aplicação de novos materiais e soluções construtivas tornam-se essenciais para diminuir a utilização de recursos naturais e energia assim como os danos resultantes da sua aplicação.  Assim, com este projeto pretende-se descrever e analisar a contribuição dos sistemas construtivos em alvenaria estrutural para os objetivos da Sustentabilidade dos Edifícios tendo como referência estudos já realizados. Em conclusão, é esperado que a solução em alvenaria estrutural para além de incluir as características técnicas exigidas, tenha menor impacte ambiental, seja economicamente vantajosa e proporcione bem-estar aos utilizadores do edifício onde possa vir a ser aplicada.