Comparative seismic vulnerability of low-to-mid-rise URM buildings in Albania: analytical assessment and observational evidence

This study presents a validated, comparative seismic performance assessment of common Albanian URM archetypes in Albania, a country recognized for its high seismic risk and large stock of masonry structures. Three representative URM buildings: two, three and five story with red and silicate clay bricks, are modelled and analyzed using the 3Muri software, to evaluate their seismic capacity and vulnerability. Experimental material tests were used to determine mechanical properties for each building, which were then applied in macro-modelling for pushover analyses according to Eurocode 8. The seismic performance was assessed at three limit states: Damage Limitation, Significant Damage, and Near Collapse, by identifying peak ground acceleration thresholds for each damage limit. Moreover, the analytical predictions were validated against field observations from the major Durrës earthquake (November 26, 2019). The two-story building demonstrated greater strength, under higher ground motions, whereas the three-story building was more vulnerable to damage. For the five-story cases, the structure with red clay bricks showed superior strength and ductility, while the silicate brick model showed lower seismic resistance and a more brittle response. Comparison with site observations after the 2019 Durrës earthquake confirmed that the predicted damage states aligned with the real damage seen in inspected buildings, particularly for non-structural and shear cracking in the masonry walls.