Seismic assessment and rehabilitation of the historical Vaniköy Mosque minaret with non-linear analysis methods

Ensuring the structural integrity of historical minarets while preserving them as cultural heritage for future generations is of paramount importance. Masonry minarets are typically constructed using adobe bricks, mud bricks, or stone, making them quite susceptible to seismic effects due to their delicate structural system. Therefore, it is crucial to assess the seismic performance of minarets in earthquake-prone areas and take measures including repair/strengthening. This study investigates the Vaniköy Mosque Minaret as a representative example of such structures. Firstly, field inspections were conducted to determine the structural system, load-bearing elements, and damage status of the minaret. Subsequently, the seismic performance of the existing and strengthened states of the minaret was determined, and the effect of the proposed improvement/strengthening methods on the seismic performance of the structure was elucidated within the scope of restoration works. The results obtained from the study are deemed significant for determining the seismic performance of historically significant minarets, establishing the analysis method to be employed, and enhancing earthquake performance. Finite element models of the existing and strengthened states were prepared to assess the performance of the minaret under static and seismic effects, and nonlinear incremental pushover analyses were conducted using the "Opensees" program. It was concluded that the existing and strengthened states of the minaret failed to meet the performance objectives defined for the DD- 3 earthquake as "Limited Damage" and DD-2 earthquake as "Controlled Damage," based on the TYDRYK-2017 criteria. Due to the limited nature of the interventions (injection, crack repair, section completions, corrosion repair, strengthening with textile-reinforced mortar, etc.) within the framework of conservation principles, the targeted performance levels were not achieved. However, the proposed strengthening method increased the ultimate strength of the existing structure by 14% to 51% in different directions. Although the repair/strengthening application did not reach the target performance level of the structure, it increased the earthquake resistance by 42% for the most critical direction. While the strengthening application increased the ultimate strength of the structure, it slightly reduced its ductility. Kinematic collapse mechanisms of the minaret were evaluated, revealing an overturning mechanism condition during the DD-1 earthquake.