Field Observations and Damage Evaluation in Reinforced Concrete Buildings after the February 6th, 2023, Kahramanmaras-Turkiye Earthquakes

On February 6, 2023, two major earthquakes (Mw 7.7 and Mw 7.6) occurred in the province of Kahramanmaras in southern Turkiye at 9-h intervals, causing a lot of loss of life and destruction in the region where approximately 16% of the country's population lives. This study provides a comprehensive summary of common structural deficiencies that occurred in reinforced concrete (RC) buildings in earthquake-prone cities and proposes actionable measures systematically for future disasters. The evaluated data are based on the field observations of the authors. The main reasons for damages in RC buildings in the observation field can be classified into two categories: (1) the errors during the design stage (strong beam-weak column, short column, soft story, pounding effects, the existence of short and unconfined lap splices, insufficient transverse reinforcement, column-beam connection failures), and (2) the errors during the construction stage (poor concrete quality, unribbed reinforcing steel bar and corrosion, incorrect placement of reinforcement bars, incorrect end hook angle and length, weak gable walls, workmanship defects). Furthermore, a comparative nonlinear finite element analysis of the seismic impacts caused by the first earthquake on an existing RC building fully collapsed in the earthquake was conducted as a case study considering Turkiye Building Earthquake Code 2018 [TBEC 2018] "Turkiye Bina Deprem Yonetmeligi," Afet ve Acil Durum Yonetimi Baskanligi, Ankara (in Turkish)]. The validity and accuracy of the reasons for damages, which were reached by the field observations, were also proven by numerical analysis results. The importance of complying with the regulations, conducting the performance evaluations and controls of the buildings according to the renewed earthquake regulations and, if necessary, repairing-strengthening works were emphasized. The loss of life and property after the earthquakes that we experienced on February 6, 2023, which were called the "Disaster of the Century", showed that Turkiye's current building stock, especially those built before a certain date, is insufficient against earthquakes.