Seismic vulnerability assessment of unreinforced masonry single story buildings in Sulaymaniyah city

Unreinforced masonry (URM) buildings are among the most vulnerable structural types in seismic regions, particularly in developing cities where construction quality and material properties vary significantly. Although seismic vulnerability of URM buildings has been widely investigated worldwide, studies incorporating locally tested material properties and calibrated analytical fragility models at the city scale remain limited. The novelty of this research is to addresses this gap by developing a comprehensive seismic vulnerability assessment framework specifically for URM buildings in Sulaymaniyah City, Iraq. This study begins with a review of established empirical and analytical techniques used globally for seismic vulnerability assessment, outlining their strengths, limitations, and typical applications. In Sulaymaniyah City, a field survey of 4,724 buildings based on the EMS-98 classification showed that most buildings fall into vulnerability classes B and C under pessimistic and optimistic scenarios, respectively, and are predominantly constructed using hollow concrete blocks. A representative URM building was analyzed through nonlinear static analysis using the Equivalent Frame Method implemented in TREMURI, with material properties obtained from experimental tests (mean compressive strength ≈ 3.0 MPa and elastic modulus ≈ 2,400 MPa). The results revealed lower lateral strength and stiffness in the x-direction, leading to higher probabilities of slight damage at low PGA levels (around 0.05g) compared to the more resilient y-direction, highlighting the importance of considering directional behavior and local material properties in seismic risk mitigation.