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- MakaleAçık Erişim2026Scopus SJRQ1Structural condition assessment of the Bamsı Beyrek observation terrace in Bayburt, Türkiye, on autonomous updated FEMs
Ergün, Mustafa; Tayfur, Bilal; Güneş, Erdi
This study involves detailed numerical and experimental investigations to assess the current structural condition of the Bamsı Beyrek steel observation terrace in Bayburt, Türkiye. The numerical dynamic characteristics of the structure were obtained by free vibration analysis conducted on the preliminary finite element model, while the experimental ones were determined through ambient vibration testing. The ultimate finite element models representing the actual state of the structure were developed through the model updating process based on the principle of minimizing the differences between numerical and experimental dynamic characteristics via the Teaching-Learning Based Optimization Algorithm. Load types and their characteristic values, potentially impacting the observation terrace during its service life, were identified according to national and international code standards. The internal forces obtained from the analysis conducted on the updated model under the influence of these loads were combined using various load combinations. The structure was then statically and dynamically checked based on the most critical responses calculated from these combinations. Structural responses are evaluated based on distributions in PMM ratios on the structure, PMM ratios of all elements according to the combination that causes the most adverse values, and maximum displacements. Consequently, considering all the findings obtained from the assessments conducted on the finite element model, which reflects the current state of the observation terrace under various loads, it has been concluded that the structure is statically and dynamically reliable and does not require any repair or strengthening procedures.
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İncele - MakaleAçık Erişim2025Scopus SJRQ1Investigation of environmental effects through long-term vibration monitoring on the structural behavior and seismic performance assessment of the Hagia Sophia Bell Tower
Yanik, Yusuf; Türker, Temel; Öztürk, Hasan Tahsin; Demirtaş, Betül; Aymelek, Abdullah; Yildirim, Ömer; Çalik, İsmet
This study presents development and application of a high-precision, multi-channel vibration measurement system to monitor structural behavior of Hagia Sophia Bell Tower. The research focused on assessing the dynamic characteristics of the tower, both through experimental measurements and numerical simulations. The study began by conducting an in-depth analysis of the tower's dynamic properties using finite element (FE) models, enabling the identification of experimental frequencies. Long-term monitoring was carried out using the newly developed vibration measurement system, complemented by a digital sensor that enabled simultaneous recording of environmental conditions such as temperature and humidity. These parameters were continuously monitored to assess their potential impact on the frequencies and dynamic responses of the tower. Subsequently, regression analyses were performed to establish the relationship between environmental factors, and the tower's structural behavior. The experimental data were used to update FE models, ensuring a more accurate representation of the tower's actual behavior under varying conditions. Earthquake analyses were also conducted on the FE models to evaluate the seismic performance. The results of the study confirmed that vibration testing, combined with environmental monitoring, was a highly effective method for detecting changes in structural behavior. The findings highlighted the significant influence of environmental factors on the dynamic characteristics, with frequency variations reaching an average of 3.6%. These effects should be considered in ongoing monitoring. It was demonstrated that updating FE models reduced numerical errors below 2.5%. These findings gave importance of integrating long-term monitoring with FE model updating, providing more accurate protection and assessment strategies.
AtıfScopus4WoS4OpenAlex4İncele - MakaleYalnız künye2024Scopus SJRQ1Evaluation of the seismic performance pre- and post-restoration of a masonry clock tower's FE model updated via experimental and optimization methods
Ergün, Mustafa; Tayfur, Bilal
This article presents comprehensive numerical and partial experimental studies to determine the seismic performance of the recently restored masonry clock tower in Bayburt before and after restoration. The numerical dynamic characteristics of the structure are obtained by free vibration analysis conducted on the preliminary finite element model, while the experimental ones are determined through ambient vibration testing. The ultimate finite element models reflecting the actual state of the structure pre- and post-restoration are created through a model updating process based on the principle of minimizing the differences between numerical and experimental dynamic properties via the Tabu Search Algorithm. Dynamic analyses of the models are carried out by the mode superposition method in the time domain, using eleven earthquake ground motion records selected considering the tectonic structure of the region and scaled to the design spectrum explicitly established to the site. Seismic responses are evaluated based on displacement, maximum-minimum principal stress, and maximum-minimum principal strain. The maximum principal stress value, the most critical parameter jeopardizing the safety of masonry structures, is 2.069 MPa before the restoration reaches 2.489 MPa, with an increase of approximately 20.3 % after the restoration. Since this value is less than the tensile strength of the masonry material, 3.120 MPa, it is not at a level that poses any risk to the structure. Other structural reactions also remain below the limit values. Therefore, according to today's seismic hazard analysis criteria, it can be said that the clock tower is safe. However, the North Anatolian Fault Zone, with high tectonic activity passing just south of the city, has the potential to produce severe earthquakes that may affect the region in the future. Therefore, it is necessary to periodically monitor the seismic behaviors of the historical masonry structures in Bayburt and take essential precautions based on the results.
AtıfScopus12WoS11OpenAlex13İncele - MakaleYalnız künye2019Scopus SJRQ1Dynamic analyses of experimentally-updated FE model of historical masonry clock towers using site-specific seismic characteristics and scaling parameters according to the 2018 Turkey building earthquake code
Genç, Ali Fuat; Ergün, Mustafa; Günaydin, M.; Altunişik, Ahmet Can; Ateş, Şevket; Okur, Fatih Yesevi; Mosallam, Ayman S.
This paper presents a dynamic analysis considering site-specific seismic characteristics for a masonry clock tower located at the city of Çorum, Turkey according to the new Turkish earthquake code. Finite element model of the tower was modeled using ANSYS software in order to determine numerical dynamic characteristics of the structure such as natural frequencies and mode shapes. Non-destructive experimental measurements were performed to extract the experimental dynamic characteristics. Experimental results were used as a reference parameter for finite element model updating to reflect the current structural behavior of clock tower. Model updating procedure was carried out by changing of initial material properties of structural stone elements, and maximum differences were reduced from 23.44% to 4.90%. Numerical results indicated that displacements have an increasing trend with the height of the clock tower. Furthermore, the maximum displacements occurred at the top point between the values of 18.88 mm to 42.5 mm. Numerical results also showed that both the maximum and minimum principal stresses occurred at the upper body (clock zone) walls and transition segment between the values of 1.08 MPa/2.86 MPa and − 0.87 MPa/−3.00 MPa, respectively. The maximum and minimum principal strains occurred at the upper body (clock zone) walls between the values of 0.65E-3/1.56E-3 and − 0.78E-3/−1.50E-3, respectively. It is also concluded that non-destructive experimental measurement is very useful method to evaluate in-situ structural identification, validate and update the initial finite element model for further analyses.
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