Asma katlı betonarme binalarda dolgu duvarların sismik performans üzerindeki etkisinin incelenmesi
Investigation of the effect of infill walls on the seismic performance of reinforced concrete buildings with mezzanine floors
- Tez No: 1018399
- Danışmanlar: DOÇ. DR. MUHAMMET ZEKİ ÖZYURT
- Tez Türü: Yüksek Lisans
- Konular: Mühendislik Bilimleri, Engineering Sciences
- Anahtar Kelimeler: İnşaat mühendisliği, Civil engineering
- Yıl: 2025
- Dil: Türkçe
- Üniversite: Sakarya Üniversitesi
- Enstitü: Fen Bilimleri Enstitüsü
- Ana Bilim Dalı: İnşaat Mühendisliği Ana Bilim Dalı
- Bilim Dalı: Yapı Bilim Dalı
- Sayfa Sayısı: Belirtilmemiş.
Özet
Türkiye'de zemin katları ticari alan olarak planlanan çok katlı betonarme binalarda, geniş ve kesintisiz hacim ihtiyacını karşılamak amacıyla asma kat uygulamaları yaygın olarak tercih edilmektedir. Ancak zemin katta asma kat oluşturulması, kat yüksekliğini artırmakta ve taşıyıcı sistem sürekliliğini bozarak yapıda belirgin rijitlik ve dayanım düzensizliklerine neden olmaktadır. Özellikle alt katlarda dolgu duvar süreksizlikleri ve taşıyıcı elemanların azaltılması, katlar arası rijitlik dağılımını olumsuz etkilemekte; bu durum deprem etkisi altında yumuşak kat oluşumu ve burulma düzensizliği riskini artırarak yapısal güvenliği zayıflatmaktadır. Geçmiş depremlerde bu tür düzensizliklere sahip yapılarda ciddi hasarların meydana gelmiş olması, dolgu duvarların sismik davranış üzerindeki etkisinin bütüncül biçimde incelenmesini gerekli kılmaktadır. Bu tez çalışmasında, asma katlı ve zemin katı ticari amaçla açık bırakılmış betonarme çerçeve sistemlerde dolgu duvar varlığının ve yokluğunun deprem performansına etkileri kapsamlı biçimde araştırılmıştır. Çalışma kapsamında 5 ve 10 katlı olmak üzere iki farklı yapı yüksekliği ele alınmış; her biri için asma kat yerleşimine bağlı olarak A1 ve A2 plan tipolojileri tanımlanmıştır. Zemin katın bir bölümünde 5,00 m yüksekliğinde boşluk, diğer bölümünde ise 2,50 m yüksekliğinde asma kat bulunacak şekilde belirgin bir rijitlik süreksizliği oluşturulmuştur. Tüm modeller dolgu duvarsız (yalın çerçeve) ve dolgu duvarlı (eşdeğer diyagonal basınç çubuğu modeli) olmak üzere iki farklı durumda modellenmiş ve toplam sekiz analiz modeli oluşturulmuştur. Yapı modelleri Sakarya ili için tanımlanan zemin ve deprem parametreleri esas alınarak oluşturulmuş; Denali, Erzincan ve Dinar depremlerine ait gerçek yer hareketi kayıtları altında doğrusal olmayan zaman tanım alanı analizleri gerçekleştirilmiştir. Performans değerlendirmesinde doğal titreşim periyotları, göreli kat ötelemeleri, maksimum çatı deplasmanları, taban kesme kuvvetleri ve plastik mafsal dağılımları esas alınmıştır. Analiz sonuçları, dolgu duvarların yapıya ek yanal rijitlik kazandırarak doğal titreşim periyotlarını belirgin biçimde kısalttığını ve özellikle 5 katlı modellerde yatay yer değiştirme taleplerini önemli ölçüde azalttığını göstermiştir. Bu modellerde dolgu duvar varlığı, maksimum çatı deplasmanlarını ve göreli kat ötelemelerini ciddi oranlarda düşürerek zemin ve asma kat seviyelerinde gelişen yumuşak kat eğilimini büyük ölçüde bastırmıştır. Bununla birlikte rijitlik artışına bağlı olarak taban kesme kuvvetlerinde artış meydana gelmiş; dolayısıyla dolgu duvarların deplasman azaltıcı etkisinin aynı zamanda iç kuvvet taleplerini değiştiren bir mekanizma yarattığı ortaya konmuştur. 10 katlı modellerde ise davranış farklılaşmıştır. Dolgu duvarlar yatay deplasmanları azaltmakla birlikte, TH1 ve TH2 deprem kayıtları altında kolon elemanlarında zorlanmaların belirgin biçimde arttığı ve hasar mekanizmasının kolon-dominant bir karakter kazandığı tespit edilmiştir. Bu sistemlerde periyodun kısalmasına bağlı olarak artan spektral ivme talepleri, özellikle asma kat seviyesinde iç kuvvet yoğunlaşmasına yol açmış; bazı senaryolarda rijitlik süreksizliği tamamen giderilememiştir. Buna karşılık dolgu duvarsız modeller her iki yükseklik grubunda da daha büyük deplasman talepleri, daha belirgin düzensizlikler ve daha olumsuz performans düzeyleri sergilemiştir. Genel olarak çalışma, dolgu duvar etkisinin tek yönlü ve her koşulda iyileştirici olmadığını açık biçimde ortaya koymuştur. 5 katlı asma katlı yapılarda dolgu duvarlar yapısal performansı iyileştirici bir rol üstlenirken, yapı yüksekliği arttıkça aynı rijitlik artışı kolon elemanlarında iç kuvvet taleplerini büyüterek hasar mekanizmasını değiştirebilmektedir. Bu bulgu, asma katlı betonarme yapılarda dolgu duvarların yalnızca mimari bir bileşen değil, yapı yüksekliği ve deprem talebi ile birlikte değerlendirilmesi gereken kritik bir yapısal parametre olduğunu göstermektedir. Tasarım ve performans değerlendirme süreçlerinde bu etkileşimin dikkate alınması, özellikle 10 katlı sistemlerde kolon güvenliğinin sağlanması açısından belirleyici öneme sahiptir.
Özet (Çeviri)
Reinforced concrete (RC) frame buildings incorporating mezzanine floors are widely adopted in contemporary urban construction. Particularly in mixed-use buildings where the ground story is allocated to commercial functions. In such configurations, the mezzanine floor is typically introduced within the ground story to maximize usable area while maintaining large open commercial spaces. Although this architectural solution offers economic and functional advantages, it simultaneously introduces significant vertical and stiffness irregularities into the structural system. The coexistence of a double-height commercial space and a partially inserted mezzanine slab within the same story creates abrupt discontinuities in story height, lateral stiffness distribution, and load transfer mechanisms. These discontinuities may substantially influence the seismic response of RC frame buildings and can trigger adverse structural behaviors such as soft-story formation, torsional irregularity, concentration of interstory drift, and undesirable redistribution of internal forces. In addition to the geometric irregularities introduced by mezzanine floors, the presence or absence of infill walls along the building height plays a decisive role in defining the actual lateral stiffness, dynamic characteristics, and damage mechanisms of RC frame systems. Although infill walls are commonly treated as non-structural elements in conventional design practice, extensive experimental and analytical research has demonstrated that they significantly participate in resisting lateral loads. Their contribution may enhance global stiffness and reduce deformation demands; However, they may also alter internal force distribution and induce concentration of seismic demands in critical structural members. Therefore, in mezzanine-floor RC buildings where stiffness discontinuities already exist, the interaction between infill walls and structural irregularities becomes even more critical and requires detailed investigation. The primary objective of this study is to systematically evaluate the seismic performance of reinforced concrete frame buildings with mezzanine floors by explicitly examining the combined effects of building height, mezzanine configuration, and infill wall participation. In particular, the study aims to quantify how infill walls modify dynamic properties, lateral deformation demands, base shear forces, and element-level damage mechanisms in vertically irregular systems. Furthermore, special emphasis is placed on understanding whether the structural role of infill walls remains beneficial across different building heights or whether their influence changes as the global structural scale increases. To achieve these objectives, a comprehensive parametric numerical study was conducted using three-dimensional nonlinear models developed in SAP 2000. To investigate the influence of structural scale, two different building heights were considered: a five-story (Z +4) structure and a ten-story (Z+9) structure. For each height category, two distinct mezzanine configurations, denoted as A1 and A2, were defined. In both topologies, the ground story is entirely allocated to commercial use. A mezzanine floor occupies only a portion of the ground story, creating a configuration where a 5.00 m high open hall coexists with a 2.50 m high mezzanine slab within the same story level. This arrangement produces a pronounced vertical stiffness discontinuity and partial interruption of load paths. The difference between A1 and A2 two lies in the geometric placement and plan distribution of the mezzanine slab, leading to variations in mass and stiffness eccentricity. For each of the four structural configurations (5-story A1, 5-story A2, 10-story A1, and 10-story A2), two alternative structural conditions were defined in terms of infill wall distribution. In the first condition, all infill walls were removed, resulting in bare RC frame systems. In the second condition, infill walls were included throughout the structure and modeled as lateral load-carrying components. As a result, a total of eight structural models were generated: 5A1-a, 5A1-b, 5A2-a, 5A2-b, 10A1-a, 10A1-b, 10A2-a, and 10A2-b, where the suffix“a”denotes the bare-frame (dolgu duvarsız) case and“b”denotes the infilled-frame (dolgu duvarlı) case. This modeling framework enables a systematic evaluation of the effects of building height, mezzanine configuration, and infill wall participation on seismic performance. The infill walls in the infilled models were represented using the equivalent diagonal compression strut approach, which is widely accepted in performance-based seismic analysis for capturing the in-plane stiffness and strength contribution of infill panels. This macro-modeling technique allows the interaction between the RC frame and the infill walls to be incorporated without excessive computational cost, while still reflecting the essential characteristics of infill-frame interaction, including stiffness enhancement and force redistribution. All RC frame members were modeled using nonlinear beam-column elements. Beams were represented with concentrated plastic hinge formulations, allowing the simulation of flexural yielding at member ends, while columns were modeled using fiber-section elements to accurately capture axial-flexural interaction and stiffness degradation under cyclic loading. Second-order (P–Δ) effects were included in all analysis to account for the influence of gravity loads on lateral stability and deformation demands. The structures were subjected to three real earthquake ground motion records selected to represent different seismic demands. The earthquake records were chosen from the PEER Ground Motion Database to ensure that they reflect characteristics corresponding to the design earthquake level (DD-2) and to provide a balanced set of records with source mechanism similar to the regional seismotectonic features. The seismic performance of the models was evaluated through nonlinear time-history analyses under these real ground motion records. The selected earthquakes include the 2002 Denali (MW 7.9), the 1992 Erzincan (MW 6.69), and the 1995 Dinar (MW 6.4) events. Prior to scaling, the selected ground motion records were processed using SeismoSignal software. Only baseline corrections were applied, without any filtering that could modify the frequency content. After correction, the uncorrected and corrected acceleration signals were compared to ensure signal integrity. The ground motions were applied in the horizontal plane of the structure, representing the main lateral directions, and all analyses were conducted under the design earthquake level (DD-2) defined in the 2018 Turkish building earthquake Code (TBDY 2018). The site conditions correspond to Sakarya Province, with soil class ZD, seismic design spectral acceleration SDS= 1.606, building importance class BKS= 3, and earthquake design class DTS = 1. Prior to the dynamic analyses, gravity loads were applied, and the structures were allowed to reach their initial equilibrium state. During the time-history simulations, key global and local response parameters were recorded, including natural vibration periods, interstory drift ratios, maximum roof displacements, base shear forces, and the formation and evolution of plastic hinges in beams and columns. The nonlinear time-history analyses demonstrate that the number of stories is a dominant parameter governing the seismic response of RC buildings with mezzanine floors. The inclusion of infill walls significantly increased the lateral stiffness of the models, resulting in a 46% to 49% reduction in the fundamental vibration periods for both 5-story and 10-story structures. While both infilled and bare five-story models exhibited comparatively controlled structural behavior, the ten-story models showed a pronounced increase in seismic sensitivity, particularly under TH1 and TH2 ground motion records. In these taller systems, relative story drifts, soft-story indices, and torsional irregularity coefficients increased significantly, and a rapid growth in plastic hinge demand beyond the Collapse Prevention (CP) limit was observed in column elements. Consistently, roof displacement demands in the ten-story models reached values several times larger than those of the five-story counterparts subjected to the same earthquake records, confirming that global deformation demand increases strongly with structural height. The presence of infill walls reduced displacement and drift demands in both high categories; However, their structural role differed markedly between the five-story and ten-story buildings. In the five-story models, infill walls provided an overall beneficial effect by increasing lateral stiffness and limiting damage. Under the TH1 (Denali) ground motion record, the bare 5-story models exhibited excessive drifts and soft-story behavior at the ground level, pushing the structure towards the Collapse Prevention performance level. However, the introduction of infill walls in these models drastically reduced roof displacements (in some cases by more than 80%) and interstory drifts, effectively eliminating beam hinges in the collapse region. Consequently, the structural performance of five-story infilled models shifted from Collapse Prevention (CP) toward Controlled Damage (life safety) and Limited Damage (immediate occupancy) levels. This clearly indicates that, for five-story mezzanine buildings, infill walls play a stabilizing role, resulting in substantially improved seismic performance. In contrast, the response of the ten-story models revealed a more complex and critical behavior. Although infill walls effectively kept beam elements within elastic limits and reduced overall deformations by shortening the natural period, this period reduction attracted significantly higher spectral accelerations. Consequently, the base shear forces in the ten-story infilled models increased dramatically compared to their bare counterparts. This substantial increase in seismic demand led to a redistribution of internal forces, causing shear and bending demands to concentrate on the vertical load-carrying members. Under TH1 and TH2 ground motion records, extensive plastic hinging beyond the CP limit developed in columns, particularly at the ground and mezzanine levels, while beams remained relatively undamaged. This phenomenon indicates a tendency toward a column-dominated response mechanism rather than the desired beam-controlled behavior. Thus, in ten-story mezzanine-floor buildings, the stiffness increase induced by infill walls may reduce global displacement demands while simultaneously amplifying internal force demands in critical vertical members, thereby increasing the vulnerability of columns under severe seismic loading. With respect to plan topologies, the comparison between A1 and A2 layouts shows that, for five-story buildings, both plan types exhibit similar seismic performance. In the ten-story models, However, partial differences were observed depending on the frequency content of the ground motion. While A1 and A2 typologies did not show a distinct superiority over one another under TH1 and TH2 ground motion records, both configurations exhibited significant column damage accumulation in the mezzanine zone. This demonstrates that planned configuration alone does not guarantee a safe response in taller mezzanine-floor buildings; instead, the seismic performance is governed primarily by the interaction between building height and the stiffness discontinuities introduced by the mezzanine floor, as well as the characteristics of the applied ground motion records. Overall, the results demonstrate that infill walls exert a dual influence on the seismic behavior of mezzanine-floor RC buildings. On the one hand, they significantly enhance lateral stiffness and reduce displacement and interstory drift demands, which is beneficial for five-story structures. On the other hand, especially in the ten-story buildings analyzed in this study, they increase base shear and column force demands, pushing critical elements towards severe damage States and promoting a column-dominated response. These findings confirm that the interaction between infill walls, building height, and mezzanine-induced irregularities is not always favorable and must be explicitly considered in seismic design and assessment. Based on the results of this study, it is strongly recommended that infill walls be explicitly included in analytical models used for the seismic assessment and design of RC buildings with mezzanine floors. In particular, for buildings exceeding five stories, the stiffness contribution of infill walls should be accounted for to accurately estimate the increased base shear and column forces. To mitigate the risk of column failure in ten-story mezzanine structures, strict adherence to the“strong column-weak beam”principle is essential, and additional measures such as shear walls or enhanced confinement at the mezzanine level should be implemented to ensure stiffness continuity and structural safety.
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