Analytical seismic fragility and vulnerability curves for Colombian informal unreinforced masonry buildings

Unreinforced masonry (URM) structures are widely used in informal housing across Colombia, and they represent a significant portion of the country’s building stock. Despite their affordability and accessibility, these structures exhibit high-seismic vulnerability, underscoring the need for detailed risk assessment and mitigation strategies. This study presents the development of fragility and vulnerability functions tailored to the Colombian context, based on a comprehensive database of over 400 URM and semi-confined masonry (CM) buildings from diverse regions. The data set captures variations in story count, wall density, and masonry unit types, enabling the identification of regional construction trends. Advanced three-dimensional macro-element analyses were used in this study, allowing for a modeling approach that accounts for nonlinear effects and coupled failure modes while ensuring computational efficiency. The results from the analyses were found to favorably compare with previous studies, validating the applicability of the developed fragility and vulnerability curves to URM buildings in Colombia and highlighting improvements in the estimation of expected damage and losses. Notably, the curves are consistent with observed damage patterns from the 1999 Armenia and 2008 Quetame earthquakes, reinforcing their validity for seismic risk assessment in Colombian URM buildings. These findings contribute to the development of a robust framework for regional seismic risk assessment, supporting ongoing efforts to reduce disaster risks and improve the resilience of the built environment in Colombia.