Evaluation of the Structural Damage Caused by the 2023 Türkiye Earthquakes in Light of the Design-Basis and Measured Ground Motion Intensities

Abstract

The 2023 Kahramanmaras earthquakes (Mw 7.7 Pazarcik and Mw 7.6 Elbistan) struck eleven cities in Turkiye within nine hours. Over 200,000 buildings collapsed or suffered severe damage, while an additional 500,000 had moderate or light damage. Following the earthquakes, the Ministry of Environment, Urbanization, and Climate Change of Turkiye conducted a rapid damage assessment survey over a broad region. The earthquakes were also recorded by a dense network of seismic stations. This study aims to investigate the relationship between the ground motion intensity measures and observed structural damage, utilizing the extensive damage assessment and ground motion data available for various locations in the affected region. Several intensity measures were employed, including effective peak ground acceleration (EPGA) and velocity (PGV), spectral accelerations and displacements for various periods (e.g. S-a0.3, S-a1, S-d0.3, S-d1). These measures were also compared with the design-basis ground motion values provided by the seismic design codes of Turkiye. Notably, the design-basis acceleration and displacement spectra, and codepredicted PGV values were mostly exceeded during the earthquakes, indicating their significance in assessing the damage. These two intensity measures also demonstrated stronger correlations with the observed structural damage compared to other measures. The comparisons with the design-basis values showed that the design spectra should be carefully scrutinized. The findings highlight the importance of a drift-based design approach, which can be based on the expected PGV, instead of a force-based design approach relying on the expected EPGA. Furthermore, this study emphasizes the importance of updating the predictions for PGV considering the consequences of the recent earthquakes.