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    Analysis of shear walls for a suitable opening
    (Ice Publishing, 2020) Can, Omer; Tayfur, Bilal
    The main purpose of shear walls in reinforced concrete structures is to resist the lateral forces affecting the structure. However, the openings created for architectural reasons significantly change the behaviour of the shear wall and cause short column formation and sudden collapse of the structure due to the openings on them. In this study, opening shear walls were analysed analytically. Twenty-nine different frames were selected and analysed according to predetermined parameters such as frame height, frame spacing, shear wall thickness, opening/frame height ratio, concrete flexibility, modulus and moment of inertia of frame columns. In this context, a total of 5200 linear elastic analyses were performed. The analysis was carried out on seven different parameters. As a result of the analysis, it has been found that there is a non-linear relationship between the opening width and the stresses in the columns, and a nonlinear relationship is predicted that it can directly trigger short column formation.
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    Evaluation of the seismic performance pre- and post-restoration of a masonry clock tower's FE model updated via experimental and optimization methods
    (Pergamon-Elsevier Science Ltd, 2024) Ergun, 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.
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    Farklı Yüksekliğe Sahip Boşluklu Perde Duvarlara ait Davranış Eğrilerinin SAP2000 OAPI ile Elde Edilmesi
    (2018) Tayfur, Bilal; Can, Ömer
    Bu çalışma kapsamında, perde duvarlarda açılan veya bırakılan pencere boşluklarının çerçeve davranışı üzerindeki etkileri incelenmiştir. Bu bağlamda, perde/çerçeve yüksekliği oranı sabit tutularak 5 farklı serbest kolon boyunun elde edilmesini sağlayacak 5 model belirlenmiştir. 5 farklı perde duvar yüksekliğine sahip çerçeveler SAP2000 OAPI aracılığıyla C# yazılım dili kullanılarak modellenmiştir. Açıkta kalan ve kısa kolon oluşumuna sebep olan boşluklara 1 cm artırımlarla kanat duvarlar eklenerek analizler yapılmıştır. Analizler çerçevenin kanat duvarsız halinden tam dolu duvar haline kadar devam ettirilmiştir. Bu sayede çerçevelere ait kanat duvar boyuna bağlı davranış değişim grafikleri elde edilmiştir. Modelleme esnasında perde duvar malzemesi, kanat duvar artırımları arasındaki kuvvet aktarımının doğru şekilde gerçekleşebilmesi için 1 cm2 meshlere ayrılmıştır. Çerçevelere ait ötelenme değerleri ve kısa kolon oluşumu beklenen kesitlerdeki iç kuvvetlerin değişimi yüksek hassasiyetle kayıt altına alınmıştır. Bu bağlamda toplam 750 farklı analiz gerçekleştirilmiştir. Bu analizler neticesinde serbest kolon boyunun kısalmasına bağlı olarak, yanal ötelenme kapasitesinin de doğrusal olmayan biçimde azaldığını ve kısa kolon oluşumu ihtimalinin arttığı görülmüştür.
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    Hybrid tabu search algorithm for weight optimization of planar steel frames
    (Taylor & Francis Ltd, 2021) Tayfur, Bilal; Yilmaz, Hamid; Daloglu, Ayse T.
    In this study, a hybrid metaheuristic algorithm called Hybrid Tabu Search (HTS) is proposed for the weight optimization of planar steel structures. The effectiveness of HTS lies in improving the initial conditions of a tabu search algorithm with a greedy search algorithm and a swap operator used in the phase of section selection. The effectiveness of the proposed method is tested and validated on three different benchmark examples. C# software is developed to perform the structural analyses. Numerical results obtained by using HTS showed that the proposed method achieved significantly lighter frame weights in most of the benchmark examples. When the method was examined in terms of computational efficiency, HTS was at a level that can compete with other algorithms examined within this study, although it did not provide a significant advantage.
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    An Investigation on the Behavior of 3D Steel Frames Under Progressive Collapse Effect Using Nonlinear Dynamic Analysis
    (Korean Soc Steel Construction-Kssc, 2023) Tayfur, Bilal; Daloglu, Ayse T.
    In this study, the nonlinear dynamic analysis of steel structures against progressive collapse was examined, and the adequacy and validity of the analysis duration defined in the regulation were investigated. In addition, the effects of the seismic resistance and design against progressive collapse constraints on the structure were investigated. An optimization algorithm was used in order to conduct the iterative process with appropriate sections. The frames were analyzed to perform one cycle as recommended in the UFC, and then the analysis duration was extended until at least five cycles had been completed. When the UFC was considered only, it was observed that while some of the designs were classified as safe within the duration specified in the UFC, the structural integrity was seen to get into danger in the subsequent cycles. When constraints related to seismic effect are also included in the process, it was seen that the threat disappeared for the frames examined. In addition, it was observed that the steel frame resisted progressive collapse scenarios by creating formations like Vierendeel beams.
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    Optimization Of Cantilever Retaining Wall Design Using Improved Teaching-Learning-Based Optimization Algorithms
    (2024) Tayfur, Bilal; Kamıloğlu, Hakan Alper
    Retaining structures play a crucial role in geotechnical engineering to support soil levels, prevent slope failure, and create flat surfaces for construction. Designing these structures involves optimizing internal and external stability while minimizing material usage and cost. This study focused on optimizing reinforced concrete cantilever retaining walls using the Teaching-Learning Based Optimization (TLBO) algorithm and an improved version (I-TLBO) with agents. In the context of the study, geometric-structural design variables, geotechnical -structural constraints, and optimization processes were examined. Minimizing weight and minimizing cost of the wall were the objectives considered in the cantilever retaining wall design process. The optimization results were compared with other algorithms in the literature, such as genetic algorithms, evolutionary strategies, and particle swarm optimization. The improved TLBO algorithm demonstrated superior performance, achieved lower design dimensions, and reduced costs. It provided more efficient solutions that pushed design constraints closer to their limits, resulting in a cost-effective and structurally sound cantilever retaining wall design. As a result of the study, the I-TLBO algorithm was found to be more cost and weight-effective than other methods in the optimization of cantilever retaining wall design.
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    Optimum design of steel frames against progressive collapse by guided simulated annealing algorithm
    (Techno-Press, 2024) Tayfur, Bilal; Daloglu, Ayse T.
    In this paper, a Guided Simulated Annealing (GSA) algorithm is presented to optimize 2D and 3D steel frames against Progressive Collapse. Considering the nature of structural optimization problems, a number of restrictions and improvements have been applied to the decision mechanisms of the algorithm without harming the randomness. With these improvements, the algorithm aims to focus relatively on the flawed variables of the analyzed frame. Besides that, it is intended to be more rational by instituting structural constraints on the sections to be selected as variables. In addition to the LRFD restrictions, the alternate path method with nonlinear dynamic procedure is used to assess the risk of progressive collapse, as specified in the US Department of Defense United Facilities Criteria (UFC) Design of Buildings to Resist Progressive Collapse. The entire optimization procedure was carried out on a C# software that supports parallel processing developed by the authors, and the frames were analyzed in SAP2000 using OAPI. Time history analyses of the removal scenarios are distributed to the processor cores in order to reduce computational time. The GSA produced 3% lighter structure weights than the SA (Simulated Annealing) and 4% lighter structure weights than the GA (Genetic Algorithm) for the 2D steel frame. For the 3D model, the GSA obtained 3% lighter results than the SA. Furthermore, it is clear that the UFC and LRFD requirements differ when the acceptance criteria are examined. It has been observed that the moment capacity of the entire frame is critical when designing according to UFC.
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    Perde duvarlarda bırakılan pencere boşluklarındaki boyut etkilerinin SAP2000 OAPI ile incelenmesi
    (Bayburt Üniversitesi, 2018) Tayfur, Bilal; Can, Ömer
    Perde duvarlar yapıların deprem altındaki davranışı açısından büyük önem taşımaktadır. Depremin yapı üzerindeki yansıması olan yanal yüklemeleri büyük ölçüde karşılayan perde duvarlar, yapının daha rijit bir davranış gösterebilmesini sağlamaktadır. Ancak mimari gereksinimler veya kontrolsüz mimari değişiklikler sebebiyle perde duvarlarda boşluklar açılabilmektedir. Bu boşlukların boyutları perde duvarın davranışını tümden etkilemektedir. Yapıya rijitlik kazandırması beklenen perde duvarlar, üzerlerindeki boşluklar nedeniyle tam aksi bir davranış göstererek kısa kolon oluşumuna sebep olabilmekte ve yapıda ani göçmelerin önünü açabilmektedir. Bu çalışmanın amacı, perde duvarlara ve üzerlerinde bırakılan boşluklara ait parametrelerin, perde duvar davranışı üzerindeki değişimlerini araştırmaktır. Bu amaç doğrultusunda davranış değişimi üzerindeki etkileri incelemek üzere bir takım parametreler belirlenmiştir. Her bir parametre için yeterli sayıda ve aralıkta değer seçilmiştir. Bu parametrelere bağlı olarak 29 farklı çerçeve modeli hazırlanmıştır. Bu modellerin detaylı biçimde incelenebilmesi için bir C# yazılımı geliştirilmiş ve genel model bu yazılıma kodlanmıştır. Geliştirilen bu yazılım sayesinde istenen modeller SAP2000'e OAPI aracılığıyla aktarılarak analiz edilmiştir. Her bir çerçeve için boşluk genişliği olabilecek minimum boyut ile maksimum boyut arasında 1 cm artırımlarla analiz edilmiştir. Bu analizlere bağlı olarak her bir çerçeve için kısa kolon oluşması olası bölgelerdeki davranış değişimi kesme kuvveti, ötelenme ve moment değerleri esas alınarak incelenmiştir. Bu kapsamda toplamda 5200 analiz gerçekleştirilmiştir.