Approximate seismic evaluation methods for large building inventories with high variability in their seismic resistance

Seismic hazard mitigation for urban infrastructures located in seismic regions is a challenge faced by many countries around the world, especially those with infrastructures known for their variability in quality of construction and compliance with the seismic codes. Two recent major earthquakes that hit the densely populated urban areas in Northwest Turkey resulted in a large-scale destruction and loss of life. Scientific studies indicate that the probability of occurrence of another severe earthquake along the North Anatolian Fault near Istanbul is quite high in the next few decades. This situation presents a serious threat to the large building stock and their occupants in Istanbul and adjacent areas. Structures in these areas are known to have high variability in their seismic resistance, which makes it difficult to estimate the potential losses in case of a major earthquake. Thus, there is an urgent need for a systematic strategy that will allow for rapid and reliable assessment of the seismic risk associated with existing buildings through an effective methodology that properly considers the local infrastructure characteristics. In this paper, approximate methods for seismic assessment of buildings are reviewed and are evaluated through their application to a group of 131 reinforced concrete frame buildings located in various seismic regions of Turkey. The results show that the recently developed preliminary methods that are customized for the local building characteristics provide improved prediction of seismic hazard, and may serve as an efficient and reliable risk assessment tool upon further improvement and calibration. The first stage procedures show large variability and result in considerable cases of misclassifications.