Farklı yükleme koşullarında geleneksel ve geliştirilmiş modüler kolon-kiriş birleşimlerinin sonlu elemanlar yöntemiyle incelenmesi
Finite element analysis of traditional and advanced modular beam-to-column connections under various loading conditions
Yazar: SİBEL HAZİNEDAR
Danışman: DOÇ. DR. ELİF AĞCAKOCA ; DR. MOHAMMAD MANZOOR NASERY
Sakarya Üniversitesi / Fen Bilimleri Enstitüsü / İnşaat Mühendisliği Ana Bilim Dalı
Derece: Yüksek Lisans, 2024
Konu: İnşaat Mühendisliği = Civil Engineering
Dizin: Rijit çelik bağlar = Rigit steel bond ; Yüksek çelik yapılar = High steel structures

Özet:
Çelik yapıların analizi ve tasarımı sırasında, bağlantı bölgelerinin doğru bir şekilde çözümlenmesi büyük önem taşımaktadır. Çünkü çelik yapının en kritik ve hassas noktalarından biri bağlantılardır. Bağlantıların yanlış tasarlanması veya zayıf bir şekilde inşa edilmesi, yapısal güvenliği ciddi şekilde tehlikeye atabilir. Bu nedenle, doğru bağlantı tasarımı, yapının dayanıklılığını ve güvenliğini sağlamak için hayati öneme sahiptir. Özellikle moment aktaran çelik çerçevelerde, kolon-kiriş bağlantılarında oluşan hasarlar depremler sonucunda ciddi bir sorun olarak ortaya çıkmaktadır. 
Bu çalışmada, çelik yapıların inşası için modüler bağlantı sistemlerinin kullanımının deprem dayanımı ve performans üzerindeki etkisini araştırılmıştır. Modüler bağlantı sistemleri, yapı elemanlarının fabrikasyon olarak üretilip, şantiyede sadece montajının gerçekleştirilmesini sağlar. Bu yaklaşım, inşaat sürecini kolaylaştırmayı ve yapıların daha güvenli hale getirilmesini amaçlamaktadır.
Çalışmada; çelik çerçevelerin bağlantı sistemleri üzerindeki performansı, sonlu elemanlar modeli oluşturularak ve ABAQUS programında doğrusal olmayan analiz yöntemiyle analiz edilerek gerçekleştirilmiştir. Farklı bağlantı tiplerinin 1G, 2G ve 1M modellerinde çelik çerçevelerin birleşim noktasının 100mm yatay deplasman yükü, 100mm düşey deplasman yükü ve FEMA 461 protokolü kullanılarak çevrimsel yükleme testleri gerçekleştirilmiştir. Von Mises gerilmeleri, deformasyon şekiller, yük taşıma kapasitesi, rijitlik-yerdeğiştirme eğrileri ve kümülatif enerji tüketimi-yerdeğiştirme eğrileri incelenmiştir.
Sonuçlara göre, yatay yüke maruz kalan 1M-Y100 modelinde uygulanan modüler bağlantı diğer bağlantı tiplerine kıyasla daha üstün performans göstermiştir. Özellikle, modüler bağlantının yük taşıma kapasitesi ve sünekliği, yapıların deprem gibi çevrimsel yüklere dayanıklılığını artırmıştır. 1G-Y100 ve 2G-Y100 çerçeveleri benzer davranış sergileyip yük taşıma kapasitelerinin de benzer olduğu görülmüştür.  
Sonlu eleman çalışmasından elde edilen grafikler incelendiğinde, 1G-D100 ve 2G-D100 modellerinin yük taşıma kapasitelerinin benzer olduğu ancak 1M-D100 modelinin daha yüksek bir kapasiteye sahip olduğu görülmüştür. Bununla birlikte, FEMA 461 protokolüne göre yapılan çevrimsel yükleme testleri, modüler bağlantıların düşük deformasyon ve daha stabil davranış sergilediğini göstermiştir. Ayrıca 1M-Ç modelinin çevrimsel yükler altında diğer modellere göre daha iyi rijitlik korunumu sağladığını ve yüksek enerji tüketimi, bu modelin daha fazla enerji absorbe etme kapasitesine sahip olduğunu ve dolayısıyla yüksek enerjili yükler altında daha dayanıklı olduğunu göstermektedir
Sonuç olarak, çelik çerçevelerin bağlantı bölgelerinin tasarımı ve güçlendirilmesi yapının dayanımı için önemli olmaktadır. Çalışmada kullanılan farklı tip modüler bağlantıların, yapıların dayanıklılığını ve deprem performansını artırmada etkili bir çözüm olabileceği sonucuna varılmıştır.

Abstract:
In the design of steel structures, the role of modular connection systems significantly influences the strength, ductility, and sustainability of buildings. These systems demonstrate superior performance compared to traditional connection methods. This study aims to evaluate the potential of modular connection systems on the seismic resistance and performance of steel structures.
Traditional steel structures are typically assembled in the field by individually installing beam and column elements, requiring rigorous engineering calculations and careful organization. However, this conventional method faces various challenges during production and assembly. In contrast, our developed modular system constructs steel buildings as prefabricated layered frames, with assembly solely conducted on-site. This approach aims to simplify and expedite the construction process. Moreover, steel elements manufactured in factories undergo stricter quality control processes, preventing craftsmanship errors and ensuring structures are built to higher quality and safety standards.
During the analysis and design of steel structures, proper resolution of connection zones is crucial as these are critical and sensitive points in steel construction. Incorrectly designed or poorly constructed connections can jeopardize structural safety significantly. In particular, damage occurring at column-beam connections in moment-resisting steel frames poses a serious issue during earthquakes, exacerbating their destructive effects. Therefore, emphasizing ductile behavior in post-earthquake studies is essential to ensure structures remain resilient against changing environmental conditions and loads over years. Ductility enhances a structure's ability to withstand earthquakes, thereby reducing casualties and minimizing material damages. Furthermore, reducing post-earthquake repairs and reconstruction needs enhances environmental sustainability.
This study aims to assess the potential of a new approach in steel structure design. Our modular system's seismic performance may contribute to making structures safer and more resilient while streamlining the construction process. Consequently, this research aims to provide a significant contribution for engineers and researchers seeking sustainable and secure solutions in steel structure design.
The study includes the development of a two-story structural system using two different frame systems created with enhanced modular and traditional methods. The first set of frames, created with traditional methods, was designed with flange plate connections, and another set of frames, constructed similarly by another frame system, was joined with gusset connections. The improved frame system developed using the modular method is detailed in this study.
This study examines the joint detail of the frame system created with flange plate connections, the joint detail of the frame system constructed with gusset connections, and the joint detail of the frame system developed with the enhanced modular method. Subsequent studies evaluated the performances of these frame systems under various load conditions, and the results were compared. The behavior of the joint point of the frame system was analyzed using the ABAQUS/CAE computer program. These analyses aimed to examine how column-beam joints responded to vertical and horizontal displacements and how the models reacted to repeated horizontal loading according to the FEMA 461 loading protocol. Additionally, insights into the strength of the specially designed column-beam joint compatible with the modular method were gained in this study.
The performance of connection systems in steel frames was analyzed by creating finite element models and using nonlinear analysis methods in ABAQUS. Steel material was defined with ideal elastoplastic behavior, homogeneous, and isotropic characteristics during the analysis. Linear quadratic interpolation continuous elements were used for profile and bolt materials in finite element modeling, and profiles and bolts were modeled using three-dimensional solid elements. Load-displacement values, von Mises stresses, stress distribution, deformation patterns, and yield conditions in the connection zone were obtained through finite element analysis (FEA). Kinematic energy consumption and load-displacement curves were also analyzed to evaluate the cumulative energy consumption in relation to displacement. These analyses contribute to a better understanding of frame system connection performance and aid in optimizing the design process.
Finite Element Analysis (FEA) is a mathematical and numerical approach widely used in engineering analyses. It begins by discretizing complex structures into smaller and simpler elements. The behavior of each element is mathematically defined, and ultimately, the collective behavior of these interconnected elements simulates the complex system's behavior. FEA is employed to investigate complex physical phenomena and loading conditions, calculate variables such as stress, displacement, and temperature distribution, and provide crucial data for design and analysis processes.
This study investigates the impact of various connection types on steel frames, focusing on von Mises stresses, stress distribution in plates, deformation patterns, yield behavior, load-carrying capacities, and load-displacement curves. The findings are summarized as follows: Traditional connection types exhibited similar behavior under displacement-controlled loading conditions. In contrast, modular system connections demonstrated superior load-carrying capacities under both displacement-controlled loading scenarios. Specifically, the 1M-Y100 model provided a 20.8% higher capacity compared to the 1G-Y100 and 2G-Y100 models, while the 1M-D100 model showed capacities 101% and 85% higher than the 1G-D100 and 2G-D100 models, respectively. This indicates that modular connections offer higher performance and durability. Additionally, the advantages of modular connections in terms of ductility and load-carrying capacity were highlighted. Energy consumption assessments revealed that the 1G-Ç and 2G-Ç models demonstrated similar performance, with the 2G-Ç model consuming 0.7% less energy. Conversely, the 1M-Ç model exhibited the highest energy consumption, consuming 8.3% and 9.1% more energy than the 1G-Ç and 2G-Ç models, respectively. This higher energy consumption indicates the 1M-Ç model's greater capacity for energy absorption and resilience under high-energy loads, suggesting that modular connections may offer performance advantages under seismic and other dynamic loads. Furthermore, the rigidity loss for the 1G-Ç and 2G-Ç models was 66.7% and 63.6%, respectively, while the 1M-Ç model experienced a 47% decrease, indicating better rigidity preservation and enhanced durability under cyclic loads. Future research could involve broader analyses under various loading conditions and material properties, and experimental validation of modular connections' performance in real structures. Structural engineers may use these insights to optimize design approaches for enhanced performance and safety.