Connection Type Effect on Dynamic Characteristics of Fire Exposed Steel Frames

Altunışık A. C., Akbulut Y. E., Başağa H. B., Mostofi S., Mosallam A., Wafa L.

International Engineering Symposium (IES’20), İzmir, Türkiye, 5 - 13 Aralık 2020, ss.180-184

  • Yayın Türü: Bildiri / Tam Metin Bildiri
  • Basıldığı Şehir: İzmir
  • Basıldığı Ülke: Türkiye
  • Sayfa Sayıları: ss.180-184
  • Karadeniz Teknik Üniversitesi Adresli: Evet

Özet

Fire incidents are increasingly recognized as one of the most serious concerns for new and existing buildings. In recent years, structural fire design has drawn much attention from researchers and has seen significant advances. One major issue in early structural fire research concerned high-rise fire. This topic was the object of various studies during the past years. Many researchers have attempted to study this concern from various perspectives. However, far too little attention has been paid to fire effects on dynamic characteristics of these structures. Therefore, this experimental study seeks to examine the effects of elevated temperature on modal behavior of steel structures with a special focus on the connection types. For this purpose, two steel portal frames have been used to conduct the operational modal analysis. These frames constituted of HEA profile and SHS profile unprotected steel. The beam and columns of each frame are having same steel profile and same cross-sectional dimensions. Also, in each frame, the beam-column connection type has been selected with respect to profile type of the model. The SHS frame has used welded connection and HEA frame has used bolt connection. The frames have undergone 3 hours of fire tests with respect to ISO 834 standard fire curve, and their dynamic characteristics, before and after the fire tests, have been measured. Assessing the results obtained from both frames show that after fire exposure, natural frequency values of both frames have been decreased. Here, the natural frequencies of the first two translational modes have been obtained. It was also found that the connection type used in SHS frame made this model more vulnerable to fire, so it experienced more deformation and had more decreases in its natural frequency values after the fire. However, the mode shapes of the models were just slightly distorted which was negligible. So there were no considerable changes in the mode shapes.