Browsing by Author "Vasconcelos, Graça"
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- Assessment of the efficiency of traditional earthquake resistant techniques for vernacular architecturePublication . Ortega, Javier; Vasconcelos, Graça; Rodrigues, Hugo; Correia, MarianaSpecific architectural elements can be identified in constructions located in regions frequently exposed to earthquakes. These earthquake resistant features were developed empirically by local communities to protect their built-up environment. Research in these traditional practices, resulting from a local seismic culture, is a relevant and positive approach, since it focuses on the strength of the system rather than on its weaknesses. Its integration into current vernacular building practices can help to preserve and retrofit surviving in-use examples while respecting their authenticity. The main goal of the present work is to assess numerically the efficiency of traditional earthquake resistant solutions to mitigate the seismic vulnerability of vernacular architecture. The paper thus presents the results of a detailed numerical study based on finite element modeling and nonlinear static (pushover) analysis intended to quantitatively evaluate the influence of each technique on the seismic behavior of vernacular constructions and to better understand their structural role under seismic loading.
- Assessment of the influence of horizontal diaphragms on the seismic performance of vernacular buildingsPublication . Ortega, Javier; Vasconcelos, Graça; Rodrigues, Hugo; Correia, MarianaThe awareness and preservation of the vernacular heritage and traditional construction techniques and materials is crucial as a key element of cultural identity. However, vernacular architecture located in earthquake prone areas can show a particularly poor seismic performance because of inadequate construction practices resulting from economic restraints and lack of resources. The horizontal diaphragms are one of the key aspects influencing the seismic behavior of buildings because of their major role transmitting the seismic actions to the vertical resisting elements of the structure. This paper presents a numerical parametric study adopted to understand the seismic behavior and resisting mechanisms of vernacular buildings according to the type of horizontal diaphragm considered. Detailed finite element modeling and nonlinear static (pushover) analyses were used to perform the thorough parametric study aimed at the evaluation and quantification of the influence of the type of diaphragm in the seismic behavior of vernacular buildings. The reference models used for this study simulate representative rammed earth and stone masonry vernacular buildings commonly found in the South of Portugal. Therefore, this paper also contributes for a better insight of the structural behavior of vernacular earthen and stone masonry typologies under seismic loading.
- Development of a Numerical Tool for the Seismic Vulnerability Assessment of Vernacular ArchitecturePublication . Ortega, Javier; Vasconcelos, Graça; Rodrigues, Hugo; Correia, Mariana; Miranda, Tiago Filipe da SilvaAiming at protecting the vernacular heritage located in earthquake prone areas, the paper presents the development and validation of the numerical tool that constitutes the core of a novel seismic vulnerability assessment method: Seismic Assessment of the Vulnerability of Vernacular Architecture Structures (SAVVAS). An extensive numerical modeling campaign was carried out to evaluate and quantify the influence of several parameters on the seismic response of vernacular buildings. The results were compiled into a database on which regression analysis could be performed to extract correlations between seismic capacity and qualitative and simple quantitative data that can be obtained from visual inspection.
- Influence of traditional earthquake-resistant techniques on the out-of-plane behaviour of stone masonry walls: Experimental and numerical assessmentPublication . Murano, Antonio; Ortega, Javier; Vasconcelos, Graça; Rodrigues, HugoThe main goal of the work is to assess the efficiency of traditional earthquake resistant solutions to improve the out-of-plane performance of stone masonry walls. Therefore, the present paper presents the results of an experimental campaign and numerical analysis performed on three stone masonry walls with a U-shaped plan configuration. Two of them were built with traditional earthquake-resistant techniques usually found in European Mediterranean area, namely steel ties and timber-laced reinforcements embedded at the corners of the walls. These techniques are specifically intended to enhance wall-to-wall connections and, thus, improve the out-of-plane behaviour of the walls. The experimental campaign included qualitative assessment procedures, non-destructive tests for the material characterization and a quasi-static test for the characterization of the out-of-plane response. Additionally, a finite element numerical model was built, calibrated with the experimental results, allowing to perform a parametric study to evaluate the influence of the number of reinforcements and geometrical configuration on the out-of-plane behaviour of stone masonry walls.
- Local Seismic Cultures: The Use of Timber Frame Structures in the South of PortugalPublication . Ortega, Javier; Vasconcelos, Graça; Rodrigues, Hugo; Correia, MarianaLocal Seismic Cultures and traditional earthquake resistant constructions and techniques arise in seismic prone regions as a reaction to earthquakes. People continuously exposed to seismic hazard eventually had to learn how to protect themselves and developed preventive measures for earthquake mitigation. These construction efforts made by local populations gave rise to the development of what was defined by Ferrigni [1] as Local Seismic Culture. In Portugal, there is a particular well-known and widely studied type of timber frame construction that can be highlighted as the most representative example of Portuguese Seismic Culture: the Pombalino construction system [2,3]. This system was devised by the government and its use for the complex reconstruction process carried out in Lisbon after the 1755 earthquake was mandatory. It can be considered as the first technical regulation regarding seismic resistance. Furthermore, local communities adopted this constructive system as a model of earthquake resistant construction and its use widely spread around the country, eventually becoming endemic of the vernacular way of building of the country. 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 [4-7], 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.
- Numerical modelling of the cyclic behavior of timber-framed structuresPublication . Lukic, Relja; Poletti, Elisa; Rodrigues, Hugo; Vasconcelos, GraçaThe present paper presents a study on the applicability of numerical models in predicting the global response of timber-framed shear walls during earthquake events. Based on previous in-plane cyclic testing of traditional timber frames with and without masonry infill, numerical models were developed to describe the cyclic response of traditional timber frame walls including flexural behavior, pinching and strength degradation. The numerical models were developed in the finite element software OpenSees with calibrated springs representing nailed connectors found in traditional half lap joints. Based on the calibrated models a study was conducted on the timber frame wall with brick infill model by varying wall configuration and analysing cumulative energy dissipation and the effect of slenderness and load capacity with increasing drift. A good correspondence was obtained with the experimental data and future work will include the application of the model to whole buildings.
- Out-of-plane behavior of stone masonry walls: experimental and numerical analysisPublication . Maccarini, Helena; Vasconcelos, Graça; Rodrigues, Hugo; Ortega, Javier; Lourenço, Paulo B.Aiming at contributing to the better understanding of the out-of-plane behavior of unreinforced stone masonry structures, this paper presents the results of an experimental and numerical campaign performed on two U-shaped walls with different masonry bonds representative of Portuguese vernacular architecture. The experimental campaign included non-destructive tests for the material characterization and an out-of-plane cyclic loading test for the characterization of the out-of-plane response. A finite element numerical model was constructed, calibrated with the experimental results, which allowed performing a nonlinear parametric study to evaluate the most influential material and geometrical parameters in the out-of-plane behavior of stone masonry walls.
- Seismic behaviour of vernacular architecturePublication . Varum, H.; Pinheiro Rodrigues, Hugo Filipe; Lourenço, Paulo B.; Vasconcelos, GraçaVernacular buildings are in several seismic prone regions a relevant part of the building stock. They represent an important part of the of the cultural legacy, and of the technological and heritage context of the society. The present paper presents a revision of the effect of recent earthquake disasters in old buildings, and discusses the influence of the main structural elements in the vulnerability of these buildings, as well as the more common failure mechanisms. Finally, it is presented a review on the elements that more contribute to the seismic behaviour and performance of vernacular buildings.
- Seismic Vulnerability and Loss Assessment of Vila Real de Santo António, Portugal: Application of a Novel MethodPublication . Ortega, Javier; Vasconcelos, Graça; Rodrigues, Hugo; Correia, MarianaThe city of Vila Real de Santo António (VRSA) was erected after the 1755 Lisbon earthquake following a Pombaline development similar to the well-known reconstruction of Lisbon downtown. It included seismic-resistant measures at an urban and architectural level, but most original buildings have nowadays been replaced or are highly altered. A research question arises whether or not and to what extent these alterations have compromised the seismic vulnerability of the historical city center. The paper presents the seismic vulnerability assessment of the historic city center of VRSA using a newly developed method: Seismic Assessment of the Vulnerability of Vernacular Architecture Structures (SAVVAS). The method proposes a numerical tool intended to estimate the seismic capacity of vernacular buildings using qualitative and simple quantitative data that can be rapidly obtained from visual inspections. The seismic vulnerability and loss assessment consider different scenarios, including the historical condition, and studies different retrofitting strategies.
- Traditional earthquake resistant techniques for vernacular architecture and local seismic cultures: A literature reviewPublication . Ortega, Javier; Vasconcelos, Graça; Rodrigues, Hugo; Correia, Mariana; Lourenço, Paulo B.Specific architectural elements can be identified in constructions located in regions frequently exposedto earthquakes. These earthquake resistant features were developed empirically by local communities toprotect their built-up environment. Research in these traditional earthquake resistant practices, resultingfrom a local seismic culture, is a relevant and positive approach, since it focuses on the strengths of asystem rather than on its weaknesses. Its integration into current vernacular building practices can helpto preserve and retrofit surviving in-use examples without prejudice to their identity. This paper presentsan overview of the most common techniques traditionally used around the world, based on literaturereview. Additionally, it identifies the use of these techniques in the Portuguese vernacular heritage inorder to contribute for the awareness and strength of the local seismic culture in Portugal.