Assessment of Seismic Behavior of Historical Masonry Cupolas: Case of Emir Saltuk Cupola

Abstract

The protection of historical masonry structures against earthquakes requires a comprehensive understanding of their nonlinear behavior; including damage and collapse mechanisms. Throughout history and in present times, these structures have undergone multiple strengthening interventions to enhance their seismic resilience. In this context, the utilization of nonlinear analysis on 3D finite element models has become a common and reliable approach. This article focuses on the seismic performance of historical Emir Saltuk Cupola of Erzurum city which is recognized as a cultural asset by the Ministry of Tourism and Culture of the Republic of Turkiye. Emir Saltuk Cupola is a rare work built in the 12th century as a monumental grave for the founder of Saltuklu Government. The study specifically examines the impact of a reinforced concrete pulley and dome, previously added to the cupola for the purposes of seismic strengthening, on its seismic behavior, force-displacement capacity, and collapse mechanism. Determining the seismic behavior of the structure is aimed to create an important reference for cupola structures, which are frequently encountered in the Turkish-Islamic geography. Notably, this study marks the first instance where advanced numerical simulation methods have been employed to analyses the cupola. Additionally, no prior research has been conducted to assess the propagation of damage and collapse mechanisms within this type of structure. Finite element model of the structure was developed considering the architectural characteristics of the cupola. The model was calibrated based on the findings of operational modal analysis. Nonlinear dynamic analyses were performed using ground motion records from significant earthquakes, including the 1992 Erzincan, 1995 Kobe and 2023 Kahramanmaras, earthquakes, to study the seismic behavior and collapse mechanisms of the cupola. The study evaluated the reinforced concrete pulley and dome in terms of maximum principal strains, maximum displacements, crack distributions, and failure mechanisms of the cupola. The reinforced concrete elements added to the structure in previous years, while assisting in a significant increase in strength capacity, did not contribute significantly to displacement capacity of the masonry. Additionally, it has been determined that under strong ground motions, these elements completely alter the collapse mechanism of the structure, leading to damage in the reinforced concrete elements and thus helping to prevent complete collapse. The findings highlight the substantial impact that strengthening interventions may be altering the seismic behavior of historical structures. Overall, this research contributes to our understanding of the seismic performance of historical masonry cupolas and emphasizes the importance of accurately assessing their behavior through advanced numerical simulations which are supported by in-situ experimentation.