João Manuel Carvalho Estevão

Seismic vulnerability assessment of historical urban centres: case study of the old city centre of Faro, Portugal

The necessity of implementing seismic vulnerability assessment procedures to the Portuguese building stock has become urgent as recent predictions indicate the possibility of the occurrence of an earthquake similar to the well-known 1755 Lisbon earthquake within the next 50 years. Obviously, at first instance, large-scale procedures should be used rather than more extensive and accurate methodologies suited for individual buildings assessment. Moreover, it is fundamental to operate in the most vulnerable areas in our built environment, typically, the historical urban centres. As it is recognised, it is within these areas, that old masonry buildings are generally concentrated, being both the most representative and vulnerable constructive typology. Comprising 354 buildings, the case study of the old city centre of Faro is herein presented aiming at analysing and evaluating the seismic vulnerability of its old masonry building stock. In order to achieve these objectives, a vulnerability-index-based methodology was used for the assessment of the seismic vulnerability of the old masonry buildings belonging to the historical centre of Faro (Ribeirinha area) carried out through detailed inspection and survey. The results obtained were analysed using a geographical information system tool. The integration of such vulnerability and loss results represents a valuable tool for city councils and/or regional authorities to plan interventions, on the basis of a global view of the site under analysis, leading this way to more accurate and comprehensive risk mitigation strategies which comply with the requirements of safety and emergency planning. The application of this large-scale scoring methodology has confirmed moderate-to-high values for the vulnerability of this particular area, which combined with its high seismicity, may be quite alarming.

Damage Evaluation of Rammed Earth Walls Subjected to Offshore Earthquakes

Raw earth is used by men as a building material for thousands of years and remains today as one of the most widespread construction systems in the world. Rammed earth and adobe are the two main earth construction techniques used in Portugal. In Algarve, which is the continental region located at Portugal southern boundary, rammed earth is the prevailing one, either in small rural buildings or in large military fortifications. The study of earth construction is justified for several reasons. First, the necessity to preserve an irreplaceable cultural and architectural heritage. Second, because it is still the most affordable resource in countries called “underdeveloped”. Finally, because it represents an environmental, social and economical sustainable alternative, which is the use of a natural, local and recyclable material. The major problems of rammed earth constructions are there vulnerability to earthquakes, and the ones related to durability issues when exposed to weather conditions. Being rammed earth a sustainable construction technique, it is very important to assess the seismic resistance of this type of traditional buildings, namely when subjected to offshore earthquakes like the one that occurred on 28 February 1969. In this work, several stochastic ground motion simulations of offshore earthquakes were carried out to assess the seismic behaviour of rammed earth walls located in the Algarve’s coastal area. Capacity curves of traditional walls in Algarve were obtained throughout pushover nonlinear static analysis. The structural performance points were obtained for different earthquake response spectra using the mechanical properties that were previously obtained in laboratory tests.

Using the new Fibre Contact Element Method for dynamic structural analysis

AbstractIn literature, there are many methods proposed for structural analysis based on discrete element formulations, mainly for nonlinear problems. One of these new methods is the Fibre Contact Element Method (FCEM). Many of these methods have been used for structural dynamic analysis problems. However, there are some questions about their precision in capturing the dynamic elastic response of structures when comparing to methods based on continuous models, like the well known Finite Element Method (FEM). For this reason, the results obtained with FCEM were extensively compared with FEM results and with laboratorial tests, to better understand the performance of this new method in capturing the elastic dynamic response of structures. Results indicate that this kind of discrete methods are able to determine the vibration modes of a structure with equal or better precision level than the obtained with FEM. FCEM was also used to capture the dynamic response of a reinforced concrete frame with infill walls,...