Comparative analysis of structural behavior of a reinforced concrete school building before and after reinforcement

In Turkiye, the seismic safety of educational buildings, especially after the February 6, 2023 Kahramanmaraş earthquakes, has made it necessary to evaluate the performance of existing school buildings. In this study, the structural behavior of a reinforced concrete school building before and after strengthening was comparatively examined, including base shear forces, story displacements, centers of mass and rigidity, moments, and periods. The structure was modeled in three dimensions in the finite element based software environment; material and suitability criteria were defined according to TBDY 2018, and analyses were performed for the existing condition. In the time-domain phase, three acceleration records (3123. 3125. 3133) selected from the AFAD database were used both unscaled (THA) and scaled (THA-M) compatible with the target spectrum. Reinforced concrete shear wall addition was added as a strengthening method, and the same analyses were repeated. The results showed that among the earthquake records, 3125 had the highest demand (biggest pga value), and 3133 (lowest pga value) had the lowest. While story displacements decreased significantly with the increase in stiffness after strengthening, an increased tendency for base shear forces was observed for various records. The convergence of the centers of mass and stiffness reduced torsional results and made the internal force distribution more harmonious. THA-M analyses yielded lower results compared to THA, reducing the spread between records. In addition, it was observed that the demands in the X direction were generally greater than those in the Y direction in most cases; this was related to the stiffness distribution and mode-mass equality, and with these findings, the study provides a practical basis for school strengthening decisions within the scope of TBDY 2018.