Browsing by Subject "Nonlinear time history analysis"

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    Comparison of nonlinear static and dynamic analyses on a R/C building
    (Association for Scientific Research, 2013) Tekin M.; Gürbüz A.; Demir A.
    In recent years, nonlinear calculation methods can be easily carried out by means of developing computer technologies. In this way, comparisons of the nonlinear methods have started to increase rapidly and more studies are carried out on regular and irregular buildings. However, it is most important to compare consistency of the methods on buildings. In this study, most common nonlinear static (pushover) and nonlinear dynamic analysis (time history analysis) methods were compared on an asymmetric planned reinforced concrete (R/C) building. Building having horizontal and vertical irregularities was 5-story. Analyses were carried out by using SAP2000 program. The results are discussed in terms of base shear, lateral displacements and top displacement ratios.
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    Effect of Hysteretic Models on Seismic Behavior of Existing RC Structures
    (American Society of Civil Engineers (ASCE), 2015) Ergun S.; Demir A.
    The aim of this study is to investigate the effect of hysteretic models on displacement demands of reinforced concrete (RC) structures having various irregularities and determine more proper hysteretic models for different types of RC structures. The RC structures having irregularities such as soft story and overhang were analyzed with nonlinear pushover and nonlinear time-history methods. Concrete compressive strength, stirrup amount, and the number of stories for the structures were variable parameters. Totally, 25,664 analyses were carried out. Displacement capacities and performance levels of structures were determined using nonlinear pushover analysis. Exceedance ratios of performance levels and displacements demanded from the structures of 100 severe ground motions that occurred worldwide were obtained using nonlinear time-history analysis (NTHA). In NTHA, various hysteretic models were used to define inelastic behavior of RC structures. The analyses show that the hysteretic models have a significant effect on displacement demands of RC structures. Finally, proper hysteretic models are suggested according to the type of structure and purpose of occupancy. © 2014 American Society of Civil Engineers.
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    Numerical assessment of a slender structure damaged during October 30, 2020, İzmir earthquake in Turkey
    (Springer Science and Business Media B.V., 2021) Demir A.; Altıok T.Y.
    The minarets, which have a tall and slender structure, are quite vulnerable to dynamic forces, i.e. earthquakes and winds. In mainly concrete minarets, since the bond between the concrete blocks is provided by only mortar, the damages caused by high tensile stresses may emerge. This study aims to simulate the behaviour of the concrete Selimiye minaret damaged during the İzmir (Seferihisar-Samos) earthquake on October 30, 2020. The nonlinear finite element model of the Selimiye minaret is created using the Concrete Damage Plasticity failure model. In the nonlinear time history analyses, the İzmir earthquake records obtained from the Bayraklı station, located the closest to the minaret, are used. The damages occurring in the transition segment of the minaret are verified with the finite element method. This study also aims to strengthen insufficient concrete minarets with an innovative, cost-effective, and better workability method. The proposed strengthening method is based on a Fabric Reinforced Concrete Mixture. Finite element models are strengthened from the inner surface using Fabric Reinforced Concrete Mixture composites reinforced with glass and steel fibers. As a result of the finite element analyses, it is concluded that the concrete minarets can be strengthened from the inner surface with the Steel Fabric Reinforced Concrete Mixture method in safety. In addition, with a parametric study, it has been determined that partial strengthening applications, which are more economical and aesthetic, can be more effective on structural performance than full strengthening applications. © 2021, The Author(s), under exclusive licence to Springer Nature B.V.