Calibration of material properties of historical masonry minaret by using operational modal test with response surface method

3rd International Civil Engineering and Architecture Congress, Trabzon, Türkiye, 12 - 14 Ekim 2023, cilt.1, ss.986-994, (Tam Metin Bildiri)

Purpose: This study employs the finite element method to calibrate the model of the Fatih Büyük Mosque minaret using

the ANSYS Workbench program, incorporating natural vibration characteristics obtained through experimentation.

Study design/methodology/approach: The minaret of the Fatih Büyük Mosque consists of seven distinct geometric

sections along its height, starting from the foundation: base, pulpit, transition segment, cylindrical or polygonal

body/shaft, balcony, upper part of the minaret body, and dome, along with stairs. A 3D model representing these various

sections is constructed using continuous elements within ANSYS Workbench. Free vibration analyses are then

conducted on the structure to determine dynamic characteristics such as natural frequencies and mode shapes, which

depend on the minaret's physical and mechanical properties. The Response Surface Method, a component of ANSYS

Workbench software, is utilized to calibrate the dynamic characteristics of the structure through finite element analysis.

The calibration process involves three steps: i) Experimental design, ii) Construction of the response surface, iii)

Optimization of the response surface. After calibrating the finite element model, a comparison is made between the

results of experimental and numerical analyses of the minaret.

Findings: Discrepancies between frequency values obtained through the ANSYS Workbench program and natural

frequencies acquired from experimental tests are apparent. However, the post-calibration method, which utilizes the

Response Surface Method within ANSYS Workbench, proves to be effective and suitable for addressing these

differences.

Originality/value: This study allows for a comparison of dynamic characteristics obtained from experimental work and

3D finite element analysis for the Fatih Büyük Mosque minaret. The model calibration is achieved by employing the

Response Surface Method. This process aids in determining the actual material properties of the structure, predicting

potential areas of damage, and identifying stress zones using the finite element method. Furthermore, it highlights that

the minaret, constructed centuries ago, and exposed to various internal and external factors, may not achieve perfect

geometric representation within the finite element environment.

Keywords: Finite element method; Analytical model updating; Response surface method; Historical masonry minaret