Seismic vulnerability assessment and characterization of the buildings in Faial island, AzoresNeves, F., Costa, A., Vicente, R., Oliveira, C. S., Varum, H. (2011). Bulletin of Earthquake Engineering.

The earthquake of the 9th of July 1998 that hit in the central group of the Azores archipelago greatly affected the islands of Faial, Pico and São Jorge, reaching a magnitude of Mw 6.2 with the epicentre located about 15 kilometres northeast of the Faial Island. This earthquake allowed the collection of an unprecedented quantity of data concerning the characterisation of the building stock and the damage suffered by construction. This is the main purpose of this research, consisting essentially of three main aspects: i) A detailed characterisation of the building stock, assigning a five category classification, from old traditional rubble stone masonry to reinforced concrete moment framed buildings; ii) A detailed damage grade classification based on the different damage mechanisms observed; and, iii) A seismic vulnerability assessment of the building stock. The results of the vulnerability assessment together with the building stock database and damage classification were integrated into a GIS tool, allowing the spatial visualization of damage scenarios, which is potentially useful for the planning of emergency response strategies and retrofitting priorities to mitigate and manage seismic risk.

Ongoing research on seismic safety assessmentDelgado, R., Costa, A., Arêde, A., Pouca, N. V., Guedes, J., Romão, X., Delgado, P., Rocha, P. (2010). Bulletin of Earthquake Engineering, 8(1): 181-199.

Research on seismic safety assessment has been the centre of great interest among the scientific community in recent years. Although the devastating impact of earthquakes on current society should be incentive enough to increase research, the development of more realistic mechanical behaviour models and the continuous enhancement of computation capabilities are paramount factors contributing a great deal to the increase of such interest. In this context, three research areas can be identified as currently leading to important developments: code related research, especially in Europe where new design codes are in the implementation process; risk analysis, namely concerning the definition of methodologies for safety assessment that involve the evaluation of the failure probability and could be included in future generations of codes; and experimental characterization of constitutive laws which provides support for the development and calibration of accurate and realistic numerical models for seismic analysis and for the adequate characterization of limit state capacities. The paper will present some of the current scientific research trends on these three seismic safety assessment related topics. Studies addressing the seismic safety assessment of structures, either probabilistically or based on code provisions, and that consider realistic nonlinear mechanical behaviour models will be focussed. Reference will also be made to experimental research on the seismic behaviour of structural elements, emphasizing its crucial role to support the development of numerical models simulating the effects of different seismic strengthening techniques. Finally, given the development of studies leading to new trends and perspectives for performance based earthquake engineering, a possible scenario for seismic design in the future is presented, emphasizing the key issues for its implementation.

In-situ cyclic tests on existing stone masonry walls and strengthening solutionsCosta, A. A., Arêde, A., Costa, A., Oliveira, C. S. (2011). Earthquake Engineering and Structural Dynamics, 40(4): 449-471.

The present work reports on an in situ experimental test campaign carried out on abandoned traditional masonry houses after the 9th July 1998 earthquake that seriously hit the Faial island of Azores. For the testing purposes, an experimental test setup was developed based on a self-equilibrated scheme, which is herein described reporting on the advantages and drawbacks of this in situ test setup.
Five specimens were tested aiming at characterizing the out-of-plane behavior of stone masonry walls and strengthening solutions recommended for post-earthquake interventions. A detailed comparison between solutions' efficiency is presented including a cost vs benefit analysis.
In order to assess the efficiency of the developed test setup for other applications on stone masonry walls, an in-plane test on an existing URM panel is also presented. Several related issues are discussed, namely the advantages of dealing with the real boundary conditions and the capacity of providing valuable information of the response, as well as a detailed analysis of the obtained results.
The authors believe that this work provides an increase in knowledge on the seismic behavior of the existing masonry constructions, resulting from the development of an in situ test setup and the efficiency quantification of strengthening solutions. Therefore, the work is thought to positively contribute for the preservation of architectural heritage and for its seismic vulnerability reduction.

Calibration and application of a continuum damage model on the simulation of stone masonry structures. Gondar church a study caseSilva, B., Guedes, J. M., Arêde, A., Costa, A. (2011). Bulletin of Earthquake Engineering, aceite para publicação.

The conservation and rehabilitation of monuments is a matter of important investigation, and the need for accurate structural analysis, capable of effectively predicting the structural behaviour of this type of constructions, under static and dynamic loads, is increasing. Currently there are numerous computational methods and tools, supported by different theories and strategies with different levels of complexity, computation time and cost which are available to perform such analyses. A complex analysis is not always synonym of a better result and the choice of a method over another depends mostly on the purpose of the analysis. This work aims at evaluating the capacity of a non linear continuum damage model (Faria et al. in Int J Solids Struct 35(14):1533–1558, 1998), originally developed for concrete structures, to simulate the behaviour of stone masonry structures. In particular, the seismic response of an old stone masonryconstruction, the Gondar church, is analysed considering different levels of geometrical and material complexity. The verification and calibration procedures use the experimental results from tests performed on stone masonry walls at the Laboratory for Earthquake and Structural Engineering of the Faculty of Engineering of Porto University and from other tests found in the bibliography (Vasconcelos in Experimental investigations on the mechanics of stone masonry: Characterization of granites and behaviour of ancient masonry shear walls. PhD Thesis, Universidade do Minho, Guimarães, Portugal, 2005). The results are compared, assessing the differences and the importance of using complex tools, such as the continuum damage model, to better simulate and understand the global behaviour of such constructions.

Avaliação da distribuição de carga em pavimentos de madeira através de ensaios in situIlharco, T., Paupério, E., Guedes, J., Costa, A., Arêde, A. (2010). 8º Congresso Nacional de Mecânica Experimental. Guimarães, Portugal.

Com a perspectiva de conhecer o comportamento estrutural de pavimentos antigos de madeira, o Núcleo de Conservação e Reabilitação de Estruturas e Património (NCREP), integrado na Faculdade de Engenharia da Universidade do Porto (FEUP), tem vindo a realizar campanhas de ensaios in situ e laboratoriais. Uma dessas campanhas consistiu na realização de ensaios de carga num pavimento de madeira de um edifício do início do séc. XX da cidade do Porto, com o objectivo de avaliar o seu comportamento quando submetido a cargas verticais, assim como a função dos seus vários elementos estruturais, vigas, tarugos e soalho. Através da aplicação de cargas verticais numa área localizada do pavimento procurou-se analisar a forma como os tarugos e o soalho materializam a distribuição de carga entre vigas. Esta distribuição, contabilizada no Eurocódigo 5 através do parâmetro Ksys, é um aspecto importante do comportamento dos pavimentos de madeira. Os resultados obtidos no ensaio de carga são ainda confrontados com os resultados de simulações numéricas de modo a concluir sobre a qualidade destas análises na simulação dos aspectos comportamentais dos pavimentos de madeira.

Ambient vibration testing and seismic analysis of a masonry chimneyLopes, V., Guedes, J., Paupério, E., Arêde, A., Costa, A. (2009). Journal of Building Appraisal, 5(2): 101-121.

At the end of the nineteenth and the beginning of the twentieth century there was a considerable development in Portugal, characterized by the flourishing of many industrial plants. Brick masonry chimneys represent some of the most interesting elements of the industrial architectural heritage of that time. This article shows the study and analysis of a chimney from a former ceramic factory that is now part of a cultural and leisure Public Park located near Porto, Portugal. The focus in this work is given on the detailed in situ survey of the chimney involving geometrical characterization, visual inspection, with damage registration, and structural and material assessment based on in situ dynamic tests. This survey allowed assessing the in situ mechanical characteristics of the chimney and to construct a realistic numerical model to evaluate the seismic vulnerability of the chimney. Two different approaches regarding the chimney damage state were followed for the calibration of the numerical model. The models from both approaches were afterwards subjected to accelerograms matching the chimney site conditions and the responses were analysed and compared. The importance of a good mechanical characterization of the materials involved is underlined in this analysis.

Determination of mechanical properties of traditional masonry walls in dwellings of Faial Island, AzoresCosta A. (2002). Earthquake Engineering and Structural Dynamics, 31(7):1361-1382.

The determination of mechanical properties of masonry walls is a fundamental pre-requisite for the characterization of the seismic response of traditional buildings, which helps on the definition of adequate rehabilitation and strengthening procedures.
This paper presents a testing campaign carried out in the Cedros region of Faial Island, Azores, hit by the July 98 earthquake, aiming at the determination of physical and mechanical properties of stone masonry walls, namely the mass density and Young’s modulus.
The paper describes the developed testing techniques as a contribution to the study and the preservation of traditional masonry buildings.

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