Seismic Damage Assessment in Hatay (Türkiye) and FRP Strengthening Strategies for Pre-2000 RC Buildings After the 2023 Kahramanmaraş Earthquake Sequence

The Hatay province, which was most affected by the 6 February 2023 Kahramanmaraş earthquakes, causing significant losses in both Türkiye and Syria, is the main study area of this research. Furthermore, following this pair of earthquakes, Hatay became the province with the most structural and geotechnical damage. The low seismic performance of reinforced concrete (RC) structures, which constitute the dominant urban building stock of the province with its rich historical architecture, has clearly revealed critical structural weaknesses and defects. This study first provides information about the seismicity of the province and its surroundings, and then obtains intensity values for four major earthquakes using two different approaches. Considering the last two earthquake hazard maps, a comparison of seismic design parameters was made for all districts within the province. Considering the high incidence of damage in RC structures built before 2000, numerical analyses were performed on structural models created using the seismic design codes of that period. The results of the numerical analysis were consistent with the damage observed in the field. In columns where shear force capacities were exceeded, reinforcement with fiber-reinforced polymer (FRP) was applied, and the results were compared. Nonlinear static pushover analyses of a 5-story RC reference building showed that the 1968-code model had shear-capacity exceedances in a significant number of columns, whereas only two ground-story columns exceeded their shear capacity in the 1975-code model. The corresponding performance ratios (PRs) reached approximately 1.46–1.48 and 1.10 for the 1968 and 1975 models, respectively. Targeted FRP strengthening reduced the PR values of deficient members to 0.14–0.17 and eliminated the identified shear-capacity exceedances. This study aims to assess geotechnical and structural damage after earthquakes, compare seismic parameters, perform structural analysis, and determine the applicability of strengthening methods. The results of this study will be an important resource, especially for the evaluation and strengthening of RC structures built before the year 2000.