Yazar "Ozturk, Yusuf" seçeneğine göre listele

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    Seismic performance of Nilüfer Hatun Bridge pre- and post-restoration under near-fault and far-fault ground motions
    (Pergamon-Elsevier Science Ltd, 2025) Sakcal, Gokhan Baris; Bagbanci, Muhammed Bilal; Ozturk, Yusuf; Cevahir, Cigdem Merit
    This study investigates the seismic performance of the Nil & uuml;fer Hatun Bridge, a historical structure in Bursa, T & uuml;rkiye, both before and after its restoration under near-fault and far-fault ground motions. Using finite element analysis (FEA), this study evaluates the bridge's dynamic characteristics, structural behavior, and damage mechanisms. Originally built during the Byzantine period with seven arches, the bridge was later reconstructed during the Ottoman period after sections were destroyed, restoring its original configuration. The modal analysis revealed significant changes in fundamental frequencies and mode shapes due to restoration, which affected the seismic response of the structure. Nonlinear dynamic analyses showed that near-fault ground motions induce larger base shear forces, greater displacements, and more concentrated damage at the piers and arches than far-fault motions, which generate resonance effects. In addition, the pre-restoration bridge exhibited higher cumulative hysteretic energy dissipation. This study offers valuable insights into the seismic resilience of historical masonry bridges, emphasizing the impact of restoration on seismic performance and providing critical information for the development of effective conservation and assessment strategies.
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    The effect of new generation polyurethane wall block on single span steel frame behavior
    (Elsevier, 2022) Sakcali, Gokhan Baris; Ozturk, Yusuf; Celik, Ilyas Devran; Davraz, Metin
    In building production industry, infill walls which are brittle elements are generally used. Nowadays, researches for alternatives to these brittle structural elements are still ongoing. In this study, low density two different polyurethane wall block (Polyurethane wall block and interlacing polyurethane wall block) are used as infill wall. In the experimental part of the study, single spanned, one frame and two infill wall frame system are prepared. Lateral loading tests of the frame systems have been performed in the laboratory. Macro and simplified micro models of the frame system has been prepared using finite element modelling (FEM) as the numerical part of the study. Incremental pushover analysis is performed for the created finite element models. From the FEM analysis results; capacities of load-displacement, stress, separation, ductility, energy dissi-pation and local buckling conditions of the frame systems are evaluated comparatively. It is seen that the finite element analysis results and the test results are compatible. The polyurethane wall added to the steel frame system increased the base shear force, system rigidity and energy dissipation capacity by approximately 64-68%, 25-40% and 50-62%, respectively. In addition, a macro model proposal is presented to simplify the modelling of the polyurethane wall block in the computer environment.