Yazar "Okur, Fatih Yesevi" seçeneğine göre listele

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    Dynamic 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
    (Pergamon-Elsevier Science Ltd, 2019) Genc, Ali Fuat; Ergun, Mustafa; Gunaydin, Murat; Altunisik, Ahmet Can; Ates, Sevket; 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 corum, 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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    Modal identification and fatigue behavior of Eynel steel arch highway bridge with calibrated models
    (Springer Heidelberg, 2021) Sunca, Fezayil; Ergun, Mustafa; Altunisik, Ahmet Can; Gunaydin, Murat; Okur, Fatih Yesevi
    In this paper, modal parameters of the Eynel steel arch highway bridge are identified and the fatigue behavior of the bridge is investigated. Modal parameters were extracted from three ambient vibration tests carried out over the period since the bridge came into service. The bridge became operational in 2009, and experimental measurements were taken in 2010, 2019, and 2021. The Enhanced Frequency Domain Decomposition (EFDD) method in the frequency domain and the Stochastic Subspace Identification (SSI) method in the time domain were used. Modal parameters were compared and any differences found over time in the measurement test results were investigated. Comparison of the results shows that changes in the natural frequencies were very limited and there was no change between the mode shapes. When experimental natural frequencies were compared, the maximum difference between the first and second measurements was calculated as 2.827%. Similarly, the maximum difference between the first and third measurements was 5.587% for the second mode, and around 3% for the other modes. This result is as expected because: (i) the bridge is not subject to heavy vehicle traffic and only connects village roads; (ii) no significant earthquake occurred during this period in the region which might have caused structural damage; (iii) no corrosion was found in the structural system elements as there was no contact with the reservoir water; (iv) no settlement or sliding occurred in the ground and boundary conditions remained unchanged. Moreover, the fatigue behavior of the bridge was investigated using the stress life method and AASHTO LRFD Bridge Design Specifications. To rationalize the results against the fatigue effects, the verified finite element model was used. From the fatigue analyses, it was concluded that the fatigue life of the bridge was within safe limits.
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    Nondestructive Experimental Measurement, Model Updating, and Fatigue Life Assessment of carsamba Suspension Bridge
    (Asce-Amer Soc Civil Engineers, 2022) Gunaydin, Murat; Sunca, Fezayil; Altunisik, Ahmet Can; Ergun, Mustafa; Okur, Fatih Yesevi
    This paper includes the structural condition assessment of a 164-m suspension bridge in accordance with numerical and experimental methods. A finite-element model was developed using SAP2000 software so that the assessment of the bridge could be calculated numerically. The operational modal analysis method was also used to obtain experimental dynamic characteristics. In this context: (i) numerical dynamic characteristics of the bridge were obtained and compared with the experimental dynamic characteristics, (ii) a model updating procedure was carried out to minimize the differences between the numerical and experimental natural frequencies, (iii) static and dynamic analyses of the bridge were carried out by using the initial and updated finite-element models, (iv) fatigue life assessment of the bridge was investigated, and (v) the utility of the bridge for pedestrians and vehicles was checked according to various regulations. The results showed that updating the finite-element model had a significant role to play in the static and dynamic behavior of the bridge. The results also demonstrated that the bridge was designed to be extremely safe against static, dynamic, and fatigue loads. Finally, it was concluded that the bridge investigated behaves as a girder bridge rather than a suspension bridge.