Browsing by Author "Hökelekli, E"

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    Investigation of seismic safety of a masonry minaret using its dynamic characteristics
    Basaran, H; Demir, A; Ercan, E; Nohutçu, H; Hökelekli, E; Kozanoglu, C
    Besides their spiritual significance, minarets are humanity's cultural heritage to the future generations due to their historical and architectural attraction. Currently, many historical masonry minarets are damaged and destroyed due to several reasons such as earthquakes and wind. Therefore, safety of these religiously significant buildings needs to be thoroughly investigated. The utmost care must be taken into account while investigating these structures. Our study investigated earthquake behavior of historical masonry minaret of Hac1 Mahmut Mosque. Destructive and non-destructive tests were carried out to determine earthquake safety of this structure. Brick-stone masonry material properties of structure were determined by accomplishing ultrasonic wave velocity, Schmidt Hammer, uniaxial compression (UAC) and indirect tension (Brazilian) tests. Determined material properties were used in the finite element analysis of the structure. To validate the numerical analysis, Operational Modal Analysis was applied to the structure and dynamic characteristics of the structure were determined. To this end, accelerometers were placed on the structure and vibrations due to environmental effects were followed. Finite element model of the minaret was updated using dynamic characteristics of the structure and the realistic numerical model of the structure was obtained. This numerical model was solved by using earthquake records of Turkey with time history analysis (THA) and the realistic earthquake behavior of the structure was introduced.
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    Seismic Assessment in a Historical Masonry Minaret by Linear and Non-linear Seismic Analyses
    Hökelekli, E; Demir, A; Ercan, E; Nohutçu, H; Karabulut, A
    Operational Modal Analysis (OMA) method is frequently used in order to determine dynamical properties of historical masonry structures. In this study, damage pattern of historical Alaca minaret which is selected as application is investigated under different ground motions by updating finite element models (FEM) depending on operational modal analysis test. Initial Finite element model was prepared in ABAQUS V10 program and numerical dynamic characteristics of minaret were determined. In addition, experimental dynamic properties of minaret were provided by operational modal analysis. Initial numerical model of brick masonry structure was calibrated via OMA method. Then, linear and non-linear seismic analyses of calibrated FEM of historical minaret were performed by using different earthquakes acceleration records that occurred in Turkey. Concrete Damage Plasticity model was taken into account in non-linear seismic analyses. As a result of the analyses, it is concluded that the stresses obtained with linear analyses aren't as realistic as the non-linear analyses results and the earthquakes can cause some damages in the minaret.
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    The behavior of concrete-encased steel composite column-beam joints under cyclic loading
    Sermet, F; Ercan, E; Hökelekli, E; Demir, A; Arisoy, B
    This study outlines the cyclic loading response of a concrete-encased steel profile composite column-reinforced concrete beam connection. The experimental study performed for an interior joint. The column in joint was designed as a concrete-encased I-steel profile composite column according to Eurocode 4, and the beam was designed as a regular reinforced concrete beam according to local building codes. In order to emphasize the effect of the joint design, different steel core orientations were used. The numerical analysis was performed using ABAQUS to predict behavior of the joint. The performance of the samples compared the load-carrying capacity, ductility, and failure type. Comparisons were made using load-displacement relationships and failure mechanisms. The analysis results showed that the failure was determined by the behavior of the beam, and the joint capacity depended on the shear capacity of the beam.