Browsing by Author "Varum, H."
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- Evaluation of analytical methodologies used to derive vulnerability functionsPublication . Silva, V.; Crowley, H.; Varum, H.; Pinho, R.; Sousa, RomainThe recognition of fragility and vulnerability functions as a fundamental tool in seismic risk assessment has led to the development of more and more complex and elaborate procedures for their computation. Although these functions have been traditionally produced using observed damage and loss data, more recent studies propose the employment of analytical methodologies as a way to overcome the frequent lack of post-earthquake data. The variation of the structural modelling approach on the estimation of building capacity has been the target of many studies in the past; however, its influence on the resulting vulnerability model for classes of buildings, the impact in loss estimations or propagation of the uncertainty to the seismic risk calculations has so far been the object of limited scrutiny. In this paper, an extensive study of static and dynamic procedures for estimating the nonlinear response of buildings has been carried out to evaluate the impact of the chosen methodology on the resulting capacity, fragility, vulnerability and risk outputs. Moreover, the computational effort and numerical stability provided by each approach have been evaluated and conclusions drawn regarding the optimal balance between accuracy and complexity. Copyright © 2013 John Wiley & Sons, Ltd.
- Experimental study of the out-of-plane behaviour of masonry infill walls with and without previous in-plane damagePublication . Furtado, A.; Arêde, A.; Varum, H.; Rodrigues, HugoRecent earthquakes demonstrated a significant contribution of the masonry infill walls in the structural response of the existent reinforced concrete buildings. When subjected to seismic actions, they tend to interact with the surrounding RC frames, which can result in different failure modes depending on the combination of the in-plane and the out-of-plane behaviour. From the surveys on damaged and collapsed RC buildings in the L’Aquila (Italy) and Lorca (Spain) earthquakes a large number of buildings that suffered severe damage or collapse had their poor performance associated with the influence of the infill panels. The masonry infill walls are considered non-structural elements but, their contribution should be considered in the structural response analysis of existing buildings, for which the understanding out-ofplane non-linear behaviour of infill walls is of full importance in order to develop efficient strengthening solutions to prevent and improve their performance in future earthquakes, and consequently reduce their seismic vulnerability. The main objective of the present paper was to obtain further knowledge concerning to the out-of-plane response of masonry infill walls panels. For this an experimental testing campaign on full scale infill walls was carried out in three experimental (cyclic and monotonic) out-of-plane tests with and without previous in-plane damage. The experimental campaign, material characterization and the test setup will be described along the manuscript as well as the main experimental tests results will be presented and discussed.
- Seismic behavior of RC building structures designed according to current codesPublication . Mosleh, A.; Rodrigues, Hugo; Varum, H.; Costa, A.; Arêde, A.Earthquakeswhich recently occurred in highly populated regions showthat existing buildings constructed without appropriate seismic resisting characteristics may constitute as an important source of risk and may cause economical loses and casualties. It is recognized the progress of the knowledge in earthquake engineering in the last decades. In this paper, two 6 irregular storey buildings were studied consisting of frame structures, representative of the common practice in Portugal, i.e. designed without considering earthquake actions. Push-over and non-linear time history analyses were done, with non-inear 3-D models in longitudinal and transverse directions. The building responseswere analyzed in two different levels: global and local. For the global response analyses: max displacement, inter-storey drift (IS drift), floor rotation for each storey and base shear were compared. For local response four columns were chosen and the variation of axial load in terms of base shear and drift as well as the biaxial demand was considered. The result shows that most variation of axial load happens in corner, facade-X, facade-Y and centre column respectively. It is noteworthy that by increasing the initial axial load the biaxial demand decreases. The seismic vulnerability was analyzed for earthquake of different return periods, and the seismic demands were compared with limit proposed in international codes and conclusion are drafted in terms of safety. The vulnerability assessment based on seismic codes clearly shows that the building 2 presented a better performance with low inter-storey drifts. The main goal of this study is considering the application andmethodology for the seismic assessment of existent real buildings. In fact this is an important topic, to understand the seismic vulnerability of certain particularities in existing buildings to assure that the common observation can be applied for a prototype building, especially irregular ones. Also one of the major observations in this study is the comprehension of the effect and importance of biaxial loading in columns and the influence of the axial load variation, relating the position of the columns in plan and in height.
- Seismic behaviour assessment of vernacular isolated buildingsPublication . Ortega, J; Vasconcelos, G; Lourenço, P; Pinheiro Rodrigues, Hugo Filipe; Varum, H.This paper presents the numerical seismic analysis of isolated vernacular buildings characteristic of the Alentejo region, which is considered a medium seismic hazard region in Portugal.A representative isolated building was selected from a database, and a geometric model was defined for the numerical pushover analysis. Subsequently, a parametric analysis was carried out to assess the influence of distinct parameters on the seismic behaviour of such buildings.
- 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 Retrofitting: Learning from Vernacular ArchitecturePublication . Costa, A.; Varum, H.; Pinheiro Rodrigues, Hugo Filipe; Lourenço, P.B.; Vasconcelos, G.; Mariana R. Correia; Paulo B. Lourenço; Humberto VarumRammed earth is one of the oldest building materials in the world, and it is present in Portugal with a particular focus in the South of the country. The mechanical properties and the structural behaviour of rammed earth constructions have been the subject of study of many researchers in the recent years. This study is part of a broader research on vernacular seismic culture in Portugal. Numerical analyses were carried out to assess the influence of different retrofitting solutions in the behaviour and seismic performance of a rammed earth building, representative of the vernacular heritage of Alentejo region. Understating the structural fragilities of this type of constructions allowed determining the most appropriate retrofitting solutions.
- Seismic vulnerability of vernacular buildings in urban centres-the case of vila real de santo antónioPublication . Vasconcelos, G.; Lourenço, P.B.; Rodrigues, H.; Varum, H.Following detailed studies of Portuguese vernacular building typologies, this paper deals with buildings located in historical urban centres. An analysis of the history of the urban centre and, in particular, of some vernacular buildings is enhanced. Additionally, a discussion on the influence of changes of the geometry, and on added built volumes to original buildings in the seismic vulnerability of the buildings is also provided.