Zemin-kazık-yapı etkileşimi ile bina devrilme analizi
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Tarih
2024
Yazarlar
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Yayıncı
Kırıkkale Üniversitesi
Erişim Hakkı
info:eu-repo/semantics/openAccess
Özet
Dünyada meydana gelen birçok depremde, bazı dar cepheli ve yüksek (narin) binaların herhangi bir yapısal hasar görmeden temeliyle birlikte devrildiği görülmüştür. Türkiye'de ise 17 Ağustos 1999 Kocaeli ve 6 Şubat 2023 Kahramanmaraş depremlerinde bazı binaların üst yapısında hiçbir hasar olmadan temeliyle birlikte eğildiği veya devrildiği görülmüştür. Büyük depremlerin etkisiyle zayıf zeminlerin taşıma kapasitesinin aşılmasına bağlı olarak bina tabanında oluşan asimetrik oturmalar temelin dönmesine sebep olmuştur. Bina tasarımında dikkate alınmayan temeldeki dönmelere bağlı olarak artan göreli kat ötelenmeleri ve ikinci mertebe momentlerin binaların devrilmesinde ciddi etkilerinin olduğu düşünülmektedir. Bu çalışma ile, 17 Ağustos 1999 Kocaeli depreminde, Adapazarı merkezinde devrilen binaların tepe ötelenmeleri devrilme limiti alınarak, devrilmeye karşı bina yükseklik/genişlik (H/B) oranının, zemin yatak katsayısına (K, kN/m3) ve en yüksek yer ivmesine (PGA, g) bağlı olarak belirlenmesi amaçlanmıştır. Bu çalışmanın ilk bölümünde, binaların devrilmesi konusunda literatür araştırması yapılmış; ancak bu konuda zemin-temel-yapı etkileşimi sebebiyle temel dönmesini de içeren detaylı bir analiz çalışmasına rastlanılmamıştır. İkinci bölümde, 17 Ağustos 1999 Kocaeli depreminde, Adapazarı merkezinde devrilerek hasar görmüş binalar ile hasar görerek devrilen binaların karıştırılabileceği düşüncesiyle, sadece eğilmiş fakat yapısal hasarı olmayan, H/B oranları 1,80, 2,00, 2,10 ve 3,00 olan dört bina referans alınmış ve en düşük H/B=1,80 olan bina devrilmede eşik sınır alınarak incelenilmiştir. Bu binaların zemin yayları çekme almayacak şekilde beş farklı zemin yatak katsayısı için ETABS programı ile modellenerek dinamik analizleri yapılmıştır. Farklı H/B oranlı diğer bina modellerinin de beş farklı zemin yatak katsayısı için analizleri yapılmış, zemin yatak katsayısı ile H/B oranı arasında lineer ve parabolik iki anlamlı bağıntı elde edilmiştir. Adapazarı özelinde zemin yatak katsayısının K=5000 kN/m3 olduğu kabul edilerek, devrilme limiti olarak H/B=1,50 oranının alınması önerilmiştir. Üçüncü bölümde, Türkiye geneli için yapılan bina devrilme analizlerinde ise devrilmeye karşı H/B oranlarını belirlemek amacıyla; 4 farklı H/B oranındaki her bir model için 5 farklı K (kN/m3) değeri ve 8 farklı PGA (g) değeri dikkate alınarak, toplam 160 dinamik analiz yapılmıştır. İkinci bölümde bulunan devrilmede H/B=1,50 limit değeri esas alınarak, Türkiye geneli için zemin yatak katsayısı ve PGA'ya bağlı H/B oranını veren logaritmik bir bağıntı elde edilmiştir. Dördüncü bölümde, devrilmeyi engellemek için H/B=1,80 bina modeline temel ile bağlantılı kazıklar eklenerek, Türkiye Bina Deprem Yönetmeliği (TBDY, 2018)'deki Yöntem-III'e göre zemin-kazık-yapı etkileşimi analizleri yapılmıştır. Yumuşak zeminlerde zemin-kazık-yapı etkileşimi hesabı için sahaya özel deprem tehlikesi analizleri ile sahaya özel deprem yer hareketi spektrumları belirlenerek sahaya özel zemin davranış analizleri gerçekleştirilmiştir. Zemin-kazık-yapı etkileşimi analizleri sonucunda temel dönmesinin ve bina tepe deplasmanlarının azaldığı ve devrilme riskinin azaldığı ve H/B oranının arttığı görülmüştür.
In many earthquakes around the world, it has been observed that some narrow-fronted and tall (slender) buildings have overturned with their foundations without any structural damage. In Türkiye, during the Kocaeli earthquakes of August 17, 1999 and the Kahramanmaraş earthquakes of February 6, 2023, some buildings were seen to be tilted or overturned along with their foundations without any damage to the superstructure. Differential settlements at the base of the building due to exceeding the bearing capacity of weak grounds as a result of large earthquakes caused the foundation to rotate. Increased relative storey drifts and second order moments due to foundation rotations, which are not taken into account in building design, are thought to have serious effects on the overturning of buildings. The aim of this study is to determine the height/width (H/B) ratio of buildings against overturning depending on the subgrade reaction coefficient (K, kN/m3) and peak ground acceleration (PGA, g) by considering the peak displacements of buildings overturned in the center of Adapazarı during the Kocaeli earthquake of August 17, 1999 as the overturning limit. In the first chapter of this study, a literature review on building overturning was conducted; however, a detailed analysis including foundation rotation due to soil-foundation-structure interaction was not found. In the second chapter, four buildings with H/B ratios of 1,80, 2,00, 2,10 and 3,00, which were only tilted but not structurally damaged, were taken as reference and the building with the lowest H/B=1,80 was taken as the threshold limit for overturning, considering that the buildings that were damaged by overturning in the center of Adapazarı during the Kocaeli earthquake of August 17, 1999 could be confused with the buildings that were damaged by overturning. The ground springs of these buildings were modeled and dynamically analyzed with ETABS program for five different subgrade reaction coefficients without tension. Other building models with different H/B ratios were also analyzed for five different subgrade reaction coefficients and two significant linear and parabolic relationships were obtained between subgrade reaction coefficient and H/B ratio. For Adapazarı, it is suggested that the subgrade reaction coefficient K=5000 kN/m3 is assumed and H/B=1,50 is taken as the overturning limit. In the third chapter, in order to determine the H/B ratios against overturning in building overturning analyses for Türkiye in general, a total of 160 dynamic analyses were performed for each model with 4 different H/B ratios, considering 5 different K (kN/m3) values and 8 different PGA (g) values. Based on the limit value of H/B=1,50 in overturning found in the second section, a logarithmic relation was obtained with for Türkiye in general, which gives the H/B ratio depending on the subgrade reaction coefficient and PGA. In the fourth chapter, soil-pile-structure interaction analyses were performed according to Method-III in Türkiye Earthquake Code (TEC-2018) by including the piles connected with the foundation in the H/B=1,80 building model to prevent overturning. Site-specific earthquake hazard analyses and site-specific earthquake ground motion spectra were determined for the calculation of soil-pile-structure interaction in soft soils and site-specific ground behavior analyses were performed. As a result of the soil-pile-structure interaction analyses, it was observed that foundation rotation and building top displacements were reduced and the risk of overturning was reduced and the H/B ratio was increased.
In many earthquakes around the world, it has been observed that some narrow-fronted and tall (slender) buildings have overturned with their foundations without any structural damage. In Türkiye, during the Kocaeli earthquakes of August 17, 1999 and the Kahramanmaraş earthquakes of February 6, 2023, some buildings were seen to be tilted or overturned along with their foundations without any damage to the superstructure. Differential settlements at the base of the building due to exceeding the bearing capacity of weak grounds as a result of large earthquakes caused the foundation to rotate. Increased relative storey drifts and second order moments due to foundation rotations, which are not taken into account in building design, are thought to have serious effects on the overturning of buildings. The aim of this study is to determine the height/width (H/B) ratio of buildings against overturning depending on the subgrade reaction coefficient (K, kN/m3) and peak ground acceleration (PGA, g) by considering the peak displacements of buildings overturned in the center of Adapazarı during the Kocaeli earthquake of August 17, 1999 as the overturning limit. In the first chapter of this study, a literature review on building overturning was conducted; however, a detailed analysis including foundation rotation due to soil-foundation-structure interaction was not found. In the second chapter, four buildings with H/B ratios of 1,80, 2,00, 2,10 and 3,00, which were only tilted but not structurally damaged, were taken as reference and the building with the lowest H/B=1,80 was taken as the threshold limit for overturning, considering that the buildings that were damaged by overturning in the center of Adapazarı during the Kocaeli earthquake of August 17, 1999 could be confused with the buildings that were damaged by overturning. The ground springs of these buildings were modeled and dynamically analyzed with ETABS program for five different subgrade reaction coefficients without tension. Other building models with different H/B ratios were also analyzed for five different subgrade reaction coefficients and two significant linear and parabolic relationships were obtained between subgrade reaction coefficient and H/B ratio. For Adapazarı, it is suggested that the subgrade reaction coefficient K=5000 kN/m3 is assumed and H/B=1,50 is taken as the overturning limit. In the third chapter, in order to determine the H/B ratios against overturning in building overturning analyses for Türkiye in general, a total of 160 dynamic analyses were performed for each model with 4 different H/B ratios, considering 5 different K (kN/m3) values and 8 different PGA (g) values. Based on the limit value of H/B=1,50 in overturning found in the second section, a logarithmic relation was obtained with for Türkiye in general, which gives the H/B ratio depending on the subgrade reaction coefficient and PGA. In the fourth chapter, soil-pile-structure interaction analyses were performed according to Method-III in Türkiye Earthquake Code (TEC-2018) by including the piles connected with the foundation in the H/B=1,80 building model to prevent overturning. Site-specific earthquake hazard analyses and site-specific earthquake ground motion spectra were determined for the calculation of soil-pile-structure interaction in soft soils and site-specific ground behavior analyses were performed. As a result of the soil-pile-structure interaction analyses, it was observed that foundation rotation and building top displacements were reduced and the risk of overturning was reduced and the H/B ratio was increased.
Açıklama
Fen Bilimleri Enstitüsü, İnşaat Mühendisliği Ana Bilim Dalı, İnşaat Mühendisliği Bilim Dalı
Anahtar Kelimeler
İnşaat Mühendisliği, Civil Engineering
