A3 türü düzensizliğine sahip yapılarda yerel zemin sınıfının yapıasal davranışı üzerindeki etkisi = The effect of local soil class on structural behavior in buildings with a3 type irregularity

Abstract

Deprem gerçeği, ülkemizin en büyük problemlerinden biri olarak, geçmiş yıllarda ciddi trajik sonuçlara sebep olmuştur. Günümüze kadar birçok büyük deprem meydana gelmiş olup, on binlerce can kaybına neden olmuştur. Coğrafi konumu itibariyle riskli bir bölgede yer alan ülkemiz için yapı tasarımı konusunda güncel olarak kullanılan 2018 Türkiye Bina Deprem Yönetmeliği, geçmiş yönetmeliklere kıyasla ciddi sınırlamalar içermektedir. Bu sınırlamalar, özellikle yapı düzensizliklerine sahip yapılar için büyük önem taşımaktadır. Genel anlamda, yapı tasarım aşamasında yapıların simetrik veya simetriğe yakın formlarda modellenmesi tercih edilmektedir. Ancak bazı kullanım amaçları, mimari gereksinimler gibi nedenlerden dolayı yapıların formu istenilen düzeyde simetrik veya düzgün olamamaktadır. Bu tür durumlarda, tasarlanan yapılar 2018 Türkiye Bina Deprem Yönetmeliği'nde belirtilen düzensizlik türlerine ait sınırlamalara uygun olarak tasarlanmaktadır. Tez kapsamındaki çalışmamızda, 1 simetrik referans model ve 6 farklı A3 türü düzensizlik katsayısına sahip toplam 7 farklı model incelenmiştir. Bu 7 model için zemin kat yükseklikleri 3 m, 4 m, 5 m ve 6 m; yerel zemin sınıfı ise ZA, ZC ve ZE olarak belirlenmiş ve toplamda 84 model analiz edilmiştir. Modellerin deprem etkisi altındaki davranışlarını incelemek için "Mod Birleştirme Analiz Yöntemi" kullanılmıştır. Bu bağlamda, yapıların periyotları, taban kesme kuvvetleri, kat ötelemeleri, göreli kat ötelemeleri, burulma düzensizliği katsayıları ve yumuşak kat düzensizliği katsayılarının sonuçları incelenmiştir. Sonuç bölümünde, incelenen yapıların A3 türü düzensizlik katsayısının değişmesinin, yerel zemin sınıfının değişmesinin ve zemin kat yüksekliğinin değişmesinin yapının hâkim periyodu, taban kesme kuvveti, kat ötelemeleri, göreli kat ötelemeleri, burulma düzensizliği katsayıları ve yumuşak kat düzensizliği katsayıları üzerindeki etkisi grafik ve tablolarla sunulmuştur. Bu analizler, yapıların deprem etkisi altındaki davranışlarını anlamak ve güvenli tasarım kriterlerini belirlemek açısından büyük önem taşımaktadır. Çalışmamız, yapı düzensizliklerinin ve zemin parametrelerinin, yapıların deprem performansı üzerindeki etkilerini daha iyi anlamamıza olanak tanımaktadır. Bu kapsamda elde edilen bulgular, deprem yönetmeliklerine uygun ve güvenli yapı tasarımı için önemli bilgiler sunmaktadır. Analiz sonuçları, mühendislik uygulamalarında dikkate alınarak, yapıların deprem dayanımını artırmak ve olası can kayıplarını minimize etmek amacıyla kullanılabilir. Tez çalışmamızın, ülkemizdeki yapı tasarımı ve deprem mühendisliği literatürüne katkı sağlaması hedeflenmektedir.

The reality of earthquakes, one of the most significant problems in our country, has led to serious and tragic consequences over the years. Numerous major earthquakes have occurred to date, resulting in tens of thousands of fatalities. Given our country's location in a geographically risky region, the 2018 Turkey Building Earthquake Regulation, currently employed in building design, incorporates significant constraints compared to previous regulations. These constraints are of undeniable importance, especially for buildings with structural irregularities. Generally, during the building design phase, we prefer to model structures in symmetrical or nearly symmetrical forms. However, due to specific usage purposes, architectural constraints, and other factors, buildings' forms cannot always be perfectly symmetrical or regular. In such cases, the designed structures are subject to the limitations specified in the 2018 Turkey Building Earthquake Regulation, which pertain to irregularity types. In our study, which falls within the scope of our thesis, a total of seven different models were examined, consisting of one symmetrical reference model and six different models with A3 type irregularity coefficients. For these seven models, with ground floor heights of 3m, 4m, 5m, and 6m, and with local soil classes ZA, ZC, and ZE, a total of 84 models were analyzed. The "Mode Superposition Method" was employed to investigate the behavior of these models under earthquake effects. In this context, we examined the results of the structures' periods, base shear forces, floor displacements, relative floor displacements, torsional irregularity coefficients, and soft story irregularity coefficients. The importance of this research lies in its comprehensive analysis of how structural irregularities, local soil classes, and ground floor heights affect buildings' seismic performance. By employing a range of models with varying characteristics, we aimed to capture a broad spectrum of potential real-world scenarios. The Mode Superposition Method allowed for a detailed examination of dynamic responses, providing insights into the resilience and vulnerability of different structural configurations. Our findings indicated that variations in A3 type irregularity coefficients, local soil classes, and ground floor heights substantially impact buildings' seismic behavior. Specifically, the dominant period of the structure, a critical parameter in seismic design, was significantly influenced by these factors. Buildings with higher irregularity coefficients exhibited longer periods, indicating a greater tendency to sway and absorb energy during seismic events. This, in turn, affects the base shear forces experienced by the structure, which are crucial for ensuring structural integrity and preventing collapse. Floor displacements and relative floor displacements are also key indicators of seismic performance. Our analysis revealed that buildings with greater irregularities and taller ground floors tended to have larger displacements, leading to higher damage levels and potential failure of structural and non-structural elements. The relationship between floor height and displacement underscores the importance of considering vertical irregularities in seismic design, as they can exacerbate horizontal irregularities' effects. Torsional irregularity coefficients and soft story irregularity coefficients were also examined in detail. Torsional irregularity, which occurs when a building twists during an earthquake, can lead to uneven force distribution and increased stress on certain parts of the structure. Our results showed that buildings with higher irregularity coefficients and unfavorable soil conditions were more prone to torsional effects, highlighting the need for careful consideration of these factors in design and retrofitting processes. Soft story irregularity, characterized by a weaker or more flexible ground floor compared to the upper floors, is a well-known vulnerability in earthquake engineering. Our study found that variations in ground floor height and soil class significantly affected the likelihood and severity of soft story behavior. Taller ground floors and certain soil conditions increased the risk of soft story collapse, emphasizing the necessity of reinforcing these areas to enhance overall building resilience. In the conclusion section of our thesis, we presented the effects of changing A3 irregularity coefficients, local soil classes, and ground floor heights on the dominant period, base shear force, floor displacements, relative floor displacements, torsional irregularity coefficients, and soft story irregularity coefficients of the analyzed structures. These results were illustrated with graphs and tables to provide a clear and comprehensive understanding of the findings. Our research contributes to the body of knowledge in earthquake engineering by offering detailed insights into the interplay between structural irregularities, soil conditions, and vertical configurations. The findings underscore the importance of adhering to the 2018 Turkey Building Earthquake Regulation and considering these factors in the design and assessment of buildings in seismically active regions. By addressing the specific vulnerabilities associated with different types of irregularities and soil classes, our study aims to inform better design practices and improve the safety and resilience of buildings against future earthquakes. Moreover, the comprehensive nature of our analysis, which includes a wide range of models and scenarios, enhances the generalizability of the results. This allows for the application of our findings to various building types and geographic contexts, providing valuable guidance for engineers, architects, and policymakers involved in seismic risk mitigation. The broader implications of our research are significant. As earthquakes continue to pose a severe threat to life and property, understanding the factors that influence a building's response to seismic activity is crucial for developing effective mitigation strategies. Our study's detailed examination of structural irregularities, soil conditions, and ground floor heights provides a nuanced understanding of how these variables interact and impact overall seismic performance. In the realm of engineering practice, our findings can guide the design of more resilient buildings. By incorporating the insights gained from our analysis, engineers can develop structures better equipped to withstand seismic forces, thereby reducing the risk of catastrophic failure. This is particularly relevant in regions with high seismic activity, where the consequences of inadequate design can be devastating. Furthermore, our research highlights the need for continuous evaluation and revision of building codes and regulations. As new data and insights emerge, updating regulations to reflect the latest understanding of seismic behavior is essential. The 2018 Turkey Building Earthquake Regulation represents a significant step forward in this regard, but ongoing research and adaptation are necessary to ensure that buildings remain safe and resilient in the face of evolving seismic risks. From an academic perspective, our thesis adds to the growing body of literature on earthquake engineering. By providing a comprehensive analysis of how various factors influence seismic performance, our work offers a valuable reference for future studies. Researchers can build on our findings to explore additional variables, refine existing models, and develop new methods for assessing and improving building resilience. In terms of practical applications, the insights from our study can inform the retrofitting of existing buildings. Many structures were built before the implementation of modern seismic regulations and may not meet current standards. Our analysis can help identify specific vulnerabilities in these buildings and guide the development of targeted retrofitting strategies to enhance their seismic performance. Our research also underscores the importance of interdisciplinary collaboration in addressing seismic risks. Engineers, architects, geologists, and policymakers must work together to develop comprehensive solutions that consider the complex interplay of structural design, soil conditions, and seismic activity. By fostering collaboration across these disciplines, we can develop more effective strategies for mitigating the impact of earthquakes and protecting communities. In conclusion, our thesis demonstrates the critical importance of considering structural irregularities, local soil conditions, and vertical configurations in seismic design. The detailed analysis and presentation of the effects of these factors on seismic performance provide a robust foundation for improving building safety and resilience. As our country continues to face the ongoing threat of earthquakes, the insights gained from this research will be instrumental in guiding future efforts to protect lives and property through better-informed engineering and design practices. By addressing the specific vulnerabilities associated with different types of irregularities and soil classes, our study aims to inform better design practices and improve the safety and resilience of buildings against future earthquakes. This comprehensive approach ensures that buildings are not only compliant with regulations but also capable of withstanding the seismic forces they may encounter. As such, our research represents a significant contribution to the field of earthquake engineering and provides valuable guidance for practitioners and policymakers alike.