Vulnerability assessment of buildings in the aftermath of 2023 Turkiye earthquake sequence

The 6 February 2023 Kahramanmaraş earthquakes in Turkiye, which measured 7.8 and 7.5 moment magnitude ( M w ) per the United States Geological Survey (USGS), affected 13 provinces and over 15 million people, according to the Turkish Government. The Earthquake Engineering Research Institute’s (EERI) Buildings Reconnaissance Team visited the populated centers as well as small towns in Turkiye that were most affected by these earthquakes. The team focused on understanding the overall structural performance of buildings, including correlation with maximum spectral acceleration and peak ground velocity at nearby ground motion recording stations. This article discusses the vulnerability of concrete buildings, which constitute most of the building stock in the region, performing an overall assessment of structural systems as well as components. More than 160 individual buildings at about 130 sites were observed. The construction period of these buildings varied from pre-2000s to as new as a few years old. Turkish building codes underwent significant changes after the 1999 Kocaeli earthquake and most recently in 2018. The findings in this article include not only the behavior of critical gravity and lateral structural elements but also the participation of non-structural elements in the seismic response of the structure, such as infills, non–load-bearing partitions, and perimeter unreinforced masonry infill walls. This article discusses the findings from field observations related to design, detailing, and construction practices. Findings illustrating the seismic performance of building systems and individual components such as floor slabs, beams, columns, shear walls, and foundations, with key takeaways to improve the seismic design guidelines, construction, and inspection practices, are summarized.