Performance of 8 Base-Isolated Hospitals During 06.02.2023 Earthquakes in Kahramanmaraş, Türkiye

On 06.02.2023 Pazarcik and Elbistan provinces of Kahramanmaras city in Turkey was hit by 2 massive earthquakes. In the close proximity of these events, there are 12 base-isolated hospitals, 8 of which have been designed and constructed with TDP double sliding surface curved surface sliders. 4 of the hospitals were under construction at various construction stage; while, other 4 was operational on 06.02.2023. Two separate site observations were made between 10.02.2023 and 19.02.2023 in all 8 hospitals and visual evaluations were made. During the visual observations in the hospitals both operational and under construction, structural and nonstructural behavior of superstructure and behavior of base isolation devices were inspected. Correct and incorrect applications of seismic gaps, infill walls, suspended ceilings; relationship between structural system and behavior of superstructure; maximum and residual displacements, torsional behavior, detailed visual inspection on sliding surfaces are some of the focuses of the observations made. All of the visual observations are summarized in this study. Then, performances of base isolation systems in all 8 hospital projects have been evaluated considering design properties of base isolation devices, results of prototype and production tests done for each specific project, DBE and MCE level design considerations of superstructures and nonlinear time history analyses performed using the actual reliable strong ground motion data published by Disaster and Emergency Management Presidency (AFAD) during the weeks after earthquakes, as well as, simulated ground motions based on commonly used attenuation relationships. This study focuses on both visual observations and analytical evaluation of performance during 06.02.2023 earthquakes of all 8 hospitals. Structural models involved nonlinear multi degree of freedom systems with lumped- mass stick model incorporating idealized story mass and stiffness for each story of the highest building block of each project. OpenSees and SAP2000 are used during modeling and nonlinear analyses.