Ozmen, Alper2026-04-042026-04-0420261330-36511848-6339https://doi.org/10.17559/TV-20241216002197https://hdl.handle.net/11616/108831This study evaluates the seismic performance and retrofitting strategies for a masonry residential building in Malatya, T & uuml;rkiye, that collapsed during the February 6, 2023, Kahramanmara & scedil; earthquake owing to an illegally added story. Nonlinear static (pushover) and dynamic (time history) analyses were performed using a finite-element macro-model. The unretrofitted structure collapsed at approximately 0.45 g in the longitudinal direction. Two retrofitting techniques, namely stainless steel strip jacketing and carbon fiber-reinforced polymer (CFRP) laminates, were investigated. The strengthened models demonstrated significantly improved seismic performance: the stainless steel strip retrofit increased the base shear capacity to 0.69 g, whereas the CFRP retrofitting further enhanced it to 0.79 g. Both methods also reduced the maximum inter storey drift ratios (from 0.50% to 0.34% for CFRP) and limited the crack widths (from 17.8 mm to less than 8 mm). CFRP retrofitting provided the most effective improvement. These results highlight the urgent need to retrofit unauthorized story additions in masonry buildings to enhance seismic resilience and inform policy decisions in seismically active regions.eninfo:eu-repo/semantics/openAccess2023 Kahramanmaras earthquakesillegal added storeymasonry buildingseismic retrofittingArticle33247048610.17559/TV-202412160021972-s2.0-105032748301Q3WOS:001707978200006Q3