The seismic assessment of masonry buildings between the 19th and 20th centuries in lisbon-evaluation of uncertainties

The article approaches the seismic vulnerability of a typology of unreinforced masonry building constructed in Lisbon between the 19th and the 20th centuries. These buildings are known within the scientific community and the public in general, by their limited performance, in terms of safety and functionality. These buildings are even named as gaioleiro buildings, meaning bird cage or gaiola buildings, in the sense that they were more adequate for birds than for people. In this article, the main architectural and structural characteristics are described in a multidisciplinary approach highlighting the main factors that contributed to the decline of the construction quality during this period of time. The architectural and structural characterization supported the definition of the case study and the identification of the main epistemic and aleatory uncertainties for class type I buildings with small size fa ades and one flat per floor. Here, the preliminary results in terms of non-linear static (pushover) analysis are presented putting in evidence the possibility of reducing the number of epistemic models initially identified. This is due to the fact that some of these models present a similar response in terms of initial stiffness, strength and maximum displacement. Future work comprehends the seismic performance-based assessment of these unreinforced masonry buildings and the derivation of analytical fragility functions.