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Code and Title:
     ICTAG I574: Development of Seismic Vulnerability Assessment Methodologies

Principal Investigator:  Prof. Dr. Güney ÖZCEBE  (homepage)


     The evaluation of seismic safety of existing buildings is one of the matters that are being investigated by the researchers especially in countries of high seismic risk. In recent years, efforts have begun to establish methods to evaluate the seismic safety of buildings to determine risks and to suggest strengthening of existing buildings.

     The observations made after the recent earthquakes demonstrated that, the buildings become less vulnerable to earthquakes with the developments in the earthquake engineering, the changes in design methods, the availability of new materials and the developments in the construction technologies. Damage statistics from recent earthquakes indicated that only a fraction of the existing buildings suffered severe earthquake damage while the remaining larger fraction did not create any life-safety hazard. Therefore, in the seismic vulnerability assessment, the main thrust should be directed towards the identification of the buildings, which create life-safety threats. Rather simple procedures are desirable to “screen-out” the majority of safe buildings. In cases where some deficiencies were detected, more detailed and sophisticated methods may be utilized.

     Serious and systematical research in the area of seismic vulnerability assessment of buildings has been realized only in the last two decades. The methodologies found in the literature are not applicable world wide due to the differences in the quality of the materials of construction, in the local construction practices, in the locally common architectural patterns etc. Therefore, rapid and yet reliable rehabilitation methodologies for Turkey must be developed.

     A reliable seismic evaluation method, which reflects the actual performance of the structure consist of three phases. These are;
      (a) a rapid screening based on simple tools,
      (b) a more refined evaluation process and 
      (c) the final evaluation stage.

    The first screening is an essential part of the study. It is in this level where the gigantic size of the existing building stock is handled and those found inadequate are identified as life-safety hazard. This step requires identification of structural attributes that can be deemed as hazardous from the point of view of seismic safety. The cities affected by the 17 August 1999 Marmara earthquake and 12 November 1999 Düzce Earthquake provide an open laboratory for this purpose. In this study, the plan is to include basic building data (damage level, number of stories, framing type, footprint, critical member sizes, location coordinates) for as many building as possible. The correlation between the damage distribution and the site conditions will also be studied. Availability of these data, focused on specific locations of heavy, medium and/or light damage, will provide a rich and useful database to test and develop methods for assessment of earthquake vulnerability in Turkey. Once the database is constructed, a rapid first-level screening index will be established to screen-out the safe buildings. This index will preferably be based on strength considerations and the expected earthquake intensity at the site.

     Later somewhat more refined and yet simple indexes will be developed to perform second and third level screening. While doing this, critical use of the established database will be made in conjunction with the current codes, i.e. the Turkish code of reinforced concrete practice (TS500-2000) and Turkish seismic code.

Keywords: Life-safety, seismic vulnerability, earthquake resistance, rapid screening, vulnerability assessment