Outline Of Field Investigation Results By The Türkiye-Japan Joint Reconnaissance Team

Due to the preliminary information on the devastating damage in the affected area due to the 2023 Türkiye-Syria Earthquakes, AIJ (Architectural Institute of Japan) JSCE (Japan Society of Civil Engineering), JGS (Japan Geotechnical Society), and Grantsin- Aid for Scientific Research team decided to organize a joint reconnaissance team. The team consisted of 27 members from Japan and 22 members from Türkiye. It was the largest international investigation team for AIJ. The target items to be investigated were Reinforced concrete (R/C), Steel, Wall-type, Masonry, Hospital, Base-isolated structures, Geotechnical issues, Strong motion characteristics, and code systems. The building damage around the strong motion observation stations was investigated to confirm if the building damage coincided with the level of measured accelerations. The widespread damages and collapses to R/C buildings showed that the structures did not have sufficient displacement capacity due to insufficient amount and detailing of transverse reinforcement. Also, the spacing between longitudinal rebars at the lap splice joints is insufficient and does not allow the proper concrete placement for achieving a sufficient bond between concrete and reinforcement. Many buildings were inclined due to uneven settlement in Gölbaşı (mostly due to liquefaction), where the soil condition was poor. The pile foundation is recommended for buildings on soft soil. A detailed investigation was also conducted to collect the dimensions of members, span lengths and heights, and material properties so that the buildings can be modeled on a computer. The code compliance system in the affected area and recovery plan were also investigated. As the conclusions, the findings and lessons from this earthquake damage were summarized. The effects of sequences of strong seismic activities as experienced during the 2023 Türkiye-Syria Earthquakes should also be further investigated.