The methodology followed by the Aristotle University (AUTh) team for the vulnerability assessment of reinforced concrete (R/C) and unreinforced masonry (URM) structures is presented. The paper focuses on the derivation of vulnerability (fragility) curves in terms of peak ground acceleration (PGA), as well as spectral displacement (s d ), and also includes the estimation of capacity curves, for several R/C and URM building types. The vulnerability assessment methodology is based on the hybrid approach developed at AUTh, which combines statistical data with appropriately processed (utilising repair cost models) results from nonlinear dynamic or static analyses, that permit extrapolation of statistical data to PGA's and/or spectral displacements for which no data are available. The statistical data used herein are from earthquake-damaged greek buildings. An extensive numerical study is carried out, wherein a large number of building types (representing most of the common typologies in S. Europe) are modelled and analysed. Vulnerability curves for several damage states are then derived using the aforementioned hybrid approach. These curves are subsequently used in combination with the mean spectrum of the Microzonation study of Thessaloniki as the basis for the derivation of new vulnerability curves involving spectral quantities. Pushover curves are derived for all building types, then reduced to standard capacity curves, and can easily be used together with the S d fragility curves as an alternative for developing seismic risk scenarios.
Reliable loss assessment (in monetary terms) for buildings struck by an earthquake is an essential factor in the development of seismic risk scenarios for a given urban area. The evaluation of loss due to building damage in a certain region depends both on seismic hazard and the vulnerability of the building stock in the area. The study presented herein consists of predicting the loss to selected groups of buildings struck by the 1999 Athens earthquake using an analytical methodology and comparison with statistical repair costs collected after the earthquake. Since no near-field strong ground motion recordings from the main shock were available, a pilot methodology was used for its analytical evaluation for different soil conditions. Different suites of motions were derived, based on various theoretical and semi-empirical approaches, and were then used in analytical investigations of the seismic behavior of the buildings in the examined area, aiming at the prediction of economic losses. An in-situ survey of about 10% of the total building stock was performed, and data regarding the structural type, actual earthquake damage, and corresponding repair costs were collected. The statistically derived repair cost for the area was compared with the economic loss estimation obtained using the analytical procedure and various estimates of the seismic action in the area considered, and was found to agree with it reasonably for some of the seismic hazard scenarios.
The effect of two types of shear reinforcement, with reference to two types of masonry infills, on the seismic performance of reinforced concrete (RC) frames was experimentally investigated. Six single-story, one-bay, 1/3-scale frame specimens were tested under cyclic horizontal loading, up to a drift level of 40‰. Bare frames and infilled frames with two different infill compressive strengths were sorted into two groups based on stirrups or spirals as shear reinforcement. From the observed responses it can be deduced that rectangular spiral reinforcement is a first experience and more experiments are needed.
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