Comparison of the predictability of the ultimate axial strength of elliptical CFST columns using existing square and circular section-based code formulae

Öz

The elliptical hollow section has been recently included in the family of the structural steel hollow sections. This type of steel section is also used in the production of concrete-filled steel tubular (CFST) members. For the elliptical CFST compression members, there is no specific design formulation in the current provisions, except the code called “Technical code for concrete-filled tubular structures” prepared by the Ministry of Housing and Urban-Rural Development of the People’s Republic of China. However, the formula proposed by this code for estimating the ultimate strength of the elliptical CFST columns was achieved by modifying the formula for predicting the ultimate strength of the square CFST members. In this context, the objective of this study is to evaluate the applicability of the existing code formulae that were proposed for the axially loaded CFST columns with rectangular or circular sections to that of columns with an elliptical section. To this, a data repository consisting of 97 experimentally tested elliptical CFST columns was compiled. Herein, the main criterion in the selection of the data was the axial loading condition. Thereafter, the prediction performance of these code formulae was assessed in terms of statistical parameters. The results indicated that the code formulae proposed for the circular-sectioned CFST columns have better prediction capability than that suggested for the rectangular sections. Among these design formulae proposed for the CFST columns with a circular section, the formulae recommended by the American Institute of Steel Construction, British Standard Institute, Canadian Standards Association, and Eurocode 4 performed the best prediction capability. These code formulae had the lowest mean absolute percent error values and R-squared values of higher than 0.8.

Anahtar Kelimeler

• Code formula
• Concrete-filled steel tubular column
• Elliptical section

Mevcut kare ve dairesel kesit tabanlı kod formüllerini kullanarak eliptik BDÇT kolonlarının nihai eksenel dayanımının tahmin edilebilirliğinin karşılaştırılması

Öz

Eliptik içi boş profil, yapısal çelik içi boş profiller ailesine son zamanlarda dahil oldu. Bu tip çelik profil, beton dolgulu çelik tüp (BDÇT) elemanların üretiminde de kullanılmaktadır. Eliptik BDÇT basınç elemanları için muayyen bir tasarım formülü, Çin Halk Cumhuriyeti Konut ve Kentsel-Kırsal Kalkınma Bakanlığınca hazırlanan “Beton dolgulu çelik tüp yapılar için teknik kod” adlı kod dışında mevcut hükümlerin kapsamında yer almamaktadır. Ancak, eliptik BDÇT kolonların nihai dayanımının tayini için önerilen bu formül, kare kesitli BDÇT elemanların nihai dayanımının tahmin edilmesinde kullanılan formülün değiştirilmesi ile elde edilmiştir. Bu bağlamda, bu çalışmanın amacı eksenel yüklenmiş dikdörtgen ve dairesel kesitli BDÇT kolonlar için önerilen mevcut kod formüllerinin eliptik kesitli bu tarz kolonlara uygulanabilirliğini değerlendirmektir. Bunun için, 97 tane deneysel olarak test edilen BDÇT kolonundan oluşan bir data havuzu oluşturuldu. Burada, data seçimindeki ana kriter, eksenel yükleme durumuydu. Sonrasında, bu kod formüllerinin tahmin performansı istatistiksek parametreler nezdinde değerlendirildi. Sonuçlar dairesel kesitli BDÇT kolonlar için önerilen kod formüllerinin dikdörtgen kesitli olanlar için önerilenlerden daha iyi tahmin kapasitesine sahip olduğunu gösterdi. Dairesel kesitli BDÇT kolonları için önerilen bu tasarım formülleri arasında ise en iyi tahmin edebilme kapasitesine, Amerikan Çelik Yapı Enstitüsü, İngiliz Standart Enstitüsü, Kanada Standartlar Birliği ve Avrupa Standartları tarafından önerilen formülleri sahipti. Bu kod formülleri en düşük ortalama mutlak yüzde hata değerlerine ve 0.8’den yüksek R-kare değerlerine sahipti.

Anahtar Kelimeler

• Kod formülü
• Beton dolgulu çelik tüp
• Eliptik kesit
• Tahmin etme
• Nihai eksenel dayanım
• Ultimate axial strength

Kaynakça

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