Structural Irregularities in Historic Masonry Structures: Analytical Assessment and Failure Mechanisms

Historic masonry structures form a significant part of cultural heritage but exhibit high seismic vulnerability due to inherent irregularities. These stem from construction variability, material heterogeneity, aging, and prior interventions, leading to non-uniform load transfer and localized damage. This study synthesizes key geometric and material irregularities and evaluates their combined impact on seismic behavior. The Fakirullah Tomb is examined as a complex case study. Results indicate that the structure behaves as interacting subsystems rather than a unified system, causing torsional effects, concentrated shear demands, and critical vulnerabilities at structural interfaces, particularly at the dome-drum and minaret connections.