Seismic behavior and failure assessment of historical masonry minarets in the Bitlis urban conservation area with numerical analysis

Abstract

Abstract Bitlis, in the Eastern Anatolia Region, has hosted many civilizations and has a rich cultural heritage. Historical masonry minarets are an important part of this heritage. These structures reflect the architectural and aesthetic features of their period and link the past and the present. In this study, eight historical masonry minarets in the urban conservation area of Bitlis were examined. Field observations and measurements were carried out, and the minarets were evaluated in terms of their structural characteristics. They were classified based on plan type, layout, shaft form, base type, transition zone, balcony arrangement, material type, and structural system. The results show both similarities and differences among the minarets. A detailed numerical analysis was performed for the minaret of Kureyşi Mosque in the city center of Bitlis. The three-dimensional finite element model was created based on data obtained from field measurements. Modal analysis was carried out to identify the dynamic characteristics of the structure. The resulting natural frequencies were calibrated against the empirical period-height relationships reported in the literature. Nonlinear time-history analyses were carried out to evaluate the seismic behavior of the minaret. Plastic strain energy (PE) was used as the main indicator. Before strengthening, the minaret showed clear nonlinear behavior and large displacements at an early stage of the ground motion. After FRP strengthening, the structural stiffness increased, and the natural frequencies became higher. The plastic strain energy was distributed more evenly after strengthening. The model also exhibited lower displacements and remained stable throughout the analysis.