Abstract
The seismic assessment of existing school buildings is an important issue in earthquake prone regions; such is the case of the Algarve, which is the southern region of Portugal mainland. Having this problem in mind, the PERSISTAH project (Projetos de Escolas Resilientes aos SISmos no Território do Algarve e de Huelva, in Portuguese) aimed to develop a computational approach enabling the damage evaluation of a large number of individual school buildings. One of the school typologies assessed was the so-called “P3” schools. This typology is composed of several different modules that are combined in different manners depending on the number of students. Each module was built in accordance with architectural standardised designs. For this reason, there are many replicas of these modules all over the Algarve region. The structural system of each module is composed of a frame of reinforced concrete (RC) elements. Nonlinear static seismic analysis procedures were adopted to evaluate the structural seismic behaviour, namely by using the new concept of performance curve. Based on the obtained results, it was possible to conclude that the seismic safety of this type of school building is mainly ruled by the shear capacity of the columns. This study also shows the difficulties of carrying out accurate seismic assessments of existing buildings using the methods of analysis that are established in the Eurocode 8.
Highlights
Algarve is a Portuguese earthquake prone region that has been affected by several destructive earthquakes in the past [1]
Because the capacity curves are used for civil protection purposes, namely for assessing the degree of damage associated with any given earthquake scenario [16], and for assessing the seismic safety level that is established in the EC3-3, a different approach was adopted in the context of the PERSISTAH project, which was already used in past seismic assessment studies [26], namely: if the Near Collapse (NC) shear capacity limit was reached during the iterative process, which corresponds to the shear capacity that is given by Equation (A.12) of EC8-3, the shear strength was reduced to a value corresponding to 20% of the initial shear strength without stopping the pushover analysis
The other reason is related to a revision of the seismic hazard of the region [30], which led to an increase of the spectral ordinates due to a combination of the change of the agR that is established for the municipalities of the Algarve region, the increase of the soil factor (S), and because the period TC presents high values, increasing the plateau of the maximum spectral acceleration despite the design seismic action of the RSAEEP being multiplied by a factor of 1.5, which can be observed in Figure 13 for the two earthquake types that are established in both seismic codes
Summary
Algarve is a Portuguese earthquake prone region that has been affected by several destructive earthquakes in the past [1]. Recent studies show that Algarve is the region where the maximum seismic intensities (I max = X) were observed in known history [2], namely due to high magnitude offshore earthquakes; such was the case of the 1 November 1755 earthquake, which is normally referred to as the “Great Lisbon Earthquake” This worldwide known catastrophic seismic event, whose effects were observed in many regions of Europe and North Africa [3], should highlight the capacity of destruction of such earthquakes and emphasize the importance of carrying out accurate seismic analysis of existing buildings to better understand what the seismic risk of this region is.
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