Different types of vertical elements, such as masonry, massive walls and timber frame elements, exhibit a different response exposed to the same loading scenario, in particular when it concerns dynamic loading. It is therefore paramount to investigate the principal response of different types of construction with different materials under a variety of loading scenarios. From there, the design of strengthening techniques against earthquakes can be performed. This paper presents the results from experiments, where various retrofitting techniques were tested. The goals were to define and improve laboratory procedures for evaluating the intervention technologies and specifications for laboratory specimens. From this base tests to characterise the experimental behaviour of original and strengthened masonry walls were performed, in order to obtain information on the system performance and the main constitutive laws relevant for modelling. The test campaigns were focused on static tests as well as cyclic tests of unreinforced and reinforced vertical building elements. The study is part of our work in the framework of the ongoing project NIKER funded by the European Commission dealing with improving immovable Cultural Heritage assets against the risk of earthquakes.
Traditional timber frame walls are an important structural element of many buildings and are usually composed of vertical posts and horizontal beams with bracing diagonal elements. In Portugal the timber frame walls, known as frontal walls, are usually part of Pombalino buildings, which were introduced by the Marquis of Pombal, who was responsible for the reconstruction of Downtown Lisbon after the great earthquake of 1755, which partially destroyed the city.
Given the increasing interest of the research community to this structural system, it is important to promote the discussion of the main findings that can contribute to the advance on the knowledge of the mechanical behaviour of timber frame buildings to seismic action.
Therefore, this paper intends: (1) to give an overview of the different solution of timber frame structures in different countries with special focus on the frontal walls characteristic of Pombalino buildings; (2) provide some examples of the reasonable behaviour of timber frame buildings in past earthquakes; (3) to summarize the experimental research carried out in the recent years in analysis of the behaviour to in-plane cyclic loading.
Half-timbered structures constitute an important cultural heritage of many countries, since they represent a typical anti-seismic construction adopted worldwide ; 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...
Tese de doutoramento
Engenharia Civil - Estruturas; Timber frame structures constitute an important cultural heritage of many countries, since
they represent a typical anti-seismic construction adopted worldwide. Therefore, the
preservation of these structures 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. Aiming at filling this research gap and at better understanding the
behaviour of these historic elements under seismic loads, an extensive experimental
campaign has been carried out, performing in-plane cyclic tests on real scale half-timbered
and timber frame walls, adopting connections and dimensions found in real structures and
considering different infill types (brick masonry and lath and plaster). Moreover, considering
possible damages caused by earthquakes, after the unreinforced tests, the walls were
retrofitted and re-tested to compare the efficiency of the retrofitting solutions in terms of
maximum load, ductility, cyclic stiffness, energy dissipation and equivalent viscous damping.
Both traditional and innovative retrofitting techniques were adopted...
Timber connections are an important part of a timber structure and a great variability exists in terms of types of connections and mechanisms. Taking as case study the traditional timber frame structures, the half-lap joint was selected. Connections play a major role in the overall behaviour of a structure, particularly when assessing their seismic response, since damage is concentrated at the connections. Therefore, an experimental campaign was carried out on traditional half-lap joints to assess their in-plane response, carrying out pull-out and in-plane cyclic tests. Subsequently, the connections were retrofitted using self-tapping screws, steel plates and GFRP sheets. In this paper, the experimental results are presented taking into account factors such as dissipated energy, damping and influence on the wall behaviour.; As ligações em madeira constituem uma parte importante das estruturas em madeira e existe uma grande variabilidade em termos de tipologia de ligações e mecânismos. Considerando como caso de estudo os edifícios com paredes de madeira tradicionais (paredes de frontal), foi adotada a ligação madeira-madeira. As ligações tem uma função fundamental no comportamento global da estrutura, em particular na analise sismica...
Traditional timber frame walls are constructive elements representative of different timber frame
buildings that are well known as one of the most efficient seismic resistant structures in the world.
Timber frame walls were also used in the reconstruction of buildings of the old town of Lisbon after
the earthquake of 1755 aiming at improving their seismic global behaviour. As it is important to
preserve these structures, a better knowledge about their behaviour under seismic actions is
important and can give some indications about possible retrofitting techniques to be used to
improve the seismic performance. Due to the great rehabilitation effort currently carried out in
many countries, a better understanding of retrofitting techniques is also needed. Therefore, this
paper aims at providing a study on possible retrofitting techniques adopting traditional solutions
such as bolts and steel plates. Static cyclic tests have been performed on retrofitted traditional
timber frame walls in order to study their seismic performance. The experimental results showed
the overall good seismic performance of steel plates and the more ductile behaviour of retrofitted
timber frame walls with bolts.; Fundação para a Ciência e a Tecnologia (FCT)
Tabique construction corresponds to a relevant Portuguese heritage. Urban and rural tabique construction exists all over the country. This traditional building technique started to be in disuse after the massive introduction of the reinforced concrete. Therefore, tabique buildings are already aged and, in general, they show signals of degradation. Recent research works have concluded that this degradation stage is essentially caused by the absence of a regular proper maintenance process. The fact that tabique buildings are mainly private property, that there are economical limitations and that there is still a lack of knowledge concerning this traditional building technique, have been the main reasons identified. In order to contribute solving this problem this paper intends to give an input on the characterization of timber frame structural system of tabique walls. In fact, a tabique building element is a structural system formed by a timber frame coated with an earthy render. The elements of the timber frame are nailed to each other. It has been noticed that there are different types of timber frames. Given technical information related to these alternative traditional structural solutions may be helpful in future rehabilitation processes. At the same time...
Em Portugal, a indústria de construção habitacional tem recorrido essencialmente às estruturas de betão armado e de alvenaria de tijolo cerâmico. As estruturas metálicas, de madeira e de alvenaria de pedra têm tido expressão reduzida nesse setor da construção, e são muito pontuais as aplicações da terra crua como solução construtiva. Nesse contexto, pretende-se estudar soluções construtivas mais sustentáveis, recorrendo a materiais de construção naturais. Para o efeito, foram estudadas para uma habitação unifamiliar com tipologia típica três soluções estruturais: estrutura porticada de betão armado e lajes aligeiradas pré-fabricadas; solução estrutural à base de materiais naturais; e solução que contempla a reutilização de madeira proveniente de demolições habitacionais. As soluções estruturais com recurso a materiais naturais estudadas são definidas por paredes resistentes de bloco de terra comprimida (BTC) e estrutura de madeira nos pavimentos e cobertura. Essas soluções estruturais são comparadas em termos de custo, gastos energéticos e teor de emissão de CO2 associados à construção. Verificou-se que as soluções mais sustentáveis são muito mais vantajosas no que diz respeito a esses três aspectos.; In Portugal...
Some of the properties sought in seismic design of buildings are also considered fundamental to guarantee structural robustness. Moreover, some key concepts are common to both seismic and robustness design. In fact, both analyses consider events with a very small probability of
occurrence, and consequently, a significant level of damage is admissible. As very rare events,in both cases, the actions are extremely hard to quantify. The acceptance of limited damage requires a system based analysis of structures, rather than an element by element methodology, as employed for other load cases.
As for robustness analysis, in seismic design the main objective is to guarantee that the structure survives an earthquake, without extensive damage. In the case of seismic design, this is achieved by guaranteeing the dissipation of energy through plastic hinges distributed in the
structure. For this to be possible, some key properties must be assured, in particular ductility and redundancy.
The same properties could be fundamental in robustness design, as a structure can only
sustain significant damage if capable of distributing stresses to parts of the structure unaffected by the triggering event.
Timber is often used for primary load‐bearing elements in single storey long‐span structures for public buildings and arenas...
Damages during extreme wind events highlight the weaknesses of mechanical fasteners at the roof-to-wall connections in residential timber frame buildings. The allowable capacity of the metal fasteners is based on results of unidirectional component testing that do not simulate realistic tri-axial aerodynamic loading effects. The first objective of this research was to simulate hurricane effects and study hurricane-structure interaction at full-scale, facilitating better understanding of the combined impacts of wind, rain, and debris on inter-component connections at spatial and temporal scales. The second objective was to evaluate the performance of a non-intrusive roof-to-wall connection system using fiber reinforced polymer (FRP) materials and compare its load capacity to the capacity of an existing metal fastener under simulated aerodynamic loads. ^ The Wall of Wind (WoW) testing performed using FRP connections on a one-story gable-roof timber structure instrumented with a variety of sensors, was used to create a database on aerodynamic and aero-hydrodynamic loading on roof-to-wall connections tested under several parameters: angles of attack, wind-turbulence content, internal pressure conditions, with and without effects of rain. Based on the aerodynamic loading results obtained from WoW tests...
Damages during extreme wind events highlight the weaknesses of mechanical fasteners at the roof-to-wall connections in residential timber frame buildings. The allowable capacity of the metal fasteners is based on results of unidirectional component testing that do not simulate realistic tri-axial aerodynamic loading effects. The first objective of this research was to simulate hurricane effects and study hurricane-structure interaction at full-scale, facilitating better understanding of the combined impacts of wind, rain, and debris on inter-component connections at spatial and temporal scales. The second objective was to evaluate the performance of a non-intrusive roof-to-wall connection system using fiber reinforced polymer (FRP) materials and compare its load capacity to the capacity of an existing metal fastener under simulated aerodynamic loads.
The Wall of Wind (WoW) testing performed using FRP connections on a one-story gable-roof timber structure instrumented with a variety of sensors, was used to create a database on aerodynamic and aero-hydrodynamic loading on roof-to-wall connections tested under several parameters: angles of attack, wind-turbulence content, internal pressure conditions, with and without effects of rain. Based on the aerodynamic loading results obtained from WoW tests...
Timber frame buildings are well known as an efficient seismic resistant structure
and they are used worldwide. Moreover, they have been specifically adopted in codes and
regulations during the XVIII and XIX centuries in the Mediterranean area. These structures
generally consist of exterior masonry walls with timber elements embedded which tie the
walls together and internal walls which have a timber frame with masonry infill and act as
shearwalls. In order to preserve these structureswhich characterizemany cities in theworld it
is important to better understand their behaviour under seismic actions. Furthermore, historic
technologies could be used even in modern constructions to build seismic resistant buildings
using more natural materials with lesser costs. Generally, different types of infill could be
applied to timber frame walls depending on the country, among which brick masonry, rubble
masonry, hay and mud. The focus of this paper is to study the seismic behaviour of the walls
considering different types of infill, specifically: masonry infill, lath and plaster and timber
frame with no infill. Static cyclic tests have been performed on unreinforced timber frame
walls in order to study their seismic capacity in terms of strength...
Timber frames are commonly adopted as a structural element in many countries with specific
characteristics varying locally, in termsof geometry and materials.Their diffusion in Southern European countries
is linked to their good seismic-resistant capacity, but only in the last decade interest has grown for this structural
typology, and studies have been performed to better understand their behaviour. In this contribution, a brief
state of the art on existing timber frame building typologies is presented, focusing on their seismic-resistant
characteristics. Additionally, an overview of possible strengthening solutions, adopted both in practice, and
tested experimentally are presented. Their performance when applied to walls and connections is also discussed.
Timber frame construction is characteristic of several historic city centres as well as of vernacular architecture in several countries around the world, either motivated by the availability of materials and construction traditions or by the need of reducing the seismic vulnerability of buildings, namely in south European countries, where this construction technique was adopted for seismic-resistance purposes. From past earthquakes, it has been seen that timber frame construction can be viewed as an interesting technology as it has exhibited a very reasonable behaviour when compared to other traditional construction techniques such as masonry walls.
This chapter provides an overview of the main insights on the seismic performance of timber frame buildings from the evidences of past earthquakes and provides the main results of recent research focused on the in-plane cyclic behavior of timber frame walls with distinct geometrical configurations. Additionally, the main seismic performance indexes of timber frame walls, both unreinforced and retrofitted, are presented and discussed in detail.
Given the fact that using timber frame structures has proven to improve the seismic behavior of
vernacular architecture, as has been reported in past earthquakes in many countries, its
preservation as a traditional earthquake resistant practice is important. This paper firstly intends
to evaluate whether the use of timber frames as a traditional seismic resistant technique for
vernacular architecture in the South of Portugal, traditionally a seismic region, is still active.
Secondly, the city of Vila Real de Santo António was selected as a case study because it also
followed a Pombaline development contemporary to the reconstruction of Lisbon. The plan
included the provision of timber frame partition walls for some of the buildings and, thus, an
overview of the type of constructions originally conceived is provided. Finally, the alterations
done in the original constructions and the current state of the city center are described and the
effect of these changes on the seismic vulnerability of the city is discussed.