An Investigation on Modal Behavior of Reinforced Concrete Column under Fire Condition - Experimental and Numerical Evaluations


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

International IDU Engineering Symposium – IES’20 , İzmir, Türkiye, 5 - 13 Aralık 2020, cilt.1, no.1, ss.1-10

  • Cilt numarası: 1
  • Basıldığı Şehir: İzmir
  • Basıldığı Ülke: Türkiye
  • Sayfa Sayıları: ss.1-10

Özet

The fire performance of the structures has been subject of research interest over the past decades. To date there exists many research works on the topic of structural analysis of building elements under the fire load. Whilst many of these studies are identifying the fire behavior of structures from mechanical and material perspectives, but they still remain narrow when it comes to determination of dynamic characteristics of fire exposed structural members.

 

Within this scope, experimental fire test provides close to real results and facilitates the evaluation of structural fire behavior. Additional to experimental studies, finite element analysis (FEA) can be used to validate the results of the experimental fire tests. Also, the use of FEA is far more feasible alternative in camper to experimental one, which allows for replication of study over various test parameters. So in order to evaluate the effect of elevated temperature on dynamic characteristics of buildings, this study conducted an experimental analysis to assess the effect of fire on structural and modal behavior of a reinforced concrete (RC) column, as one of the most important load-bearing elements of the buildings. Afterwards, FEA has been used to confirm the results obtained from both thermal and modal evaluation of the performed experimental test, concentrating on elevated temperature effects on changes in dynamic characteristic of RC column. Initially, an experimental fire furnace test was conducted over a RC column with height of 1.5m and square cross-section of 0.2m. Besides, the dynamic characteristics of test specimen have been recorded both before and after of the fire test. Followingly, FEA software has been used for cross validation of experimental results. Thus, the comparison between the experimental and FEA is to be used as the basis of modal analysis of RC column under the fire load. The ISO 834 standard fire curve with exposure duration of 3 hours has been used for both experimental and FEA. The results show the effects of fire on changes in dynamic characteristics of RC columns. It is also observed that increases in temperature reduces the natural frequency of RC column. In addition, the mode shapes of RC column are also affected by high temperature. However, no specific pattern could be obtained explaining the changes in mode shapes of RC column under the fire load. Furthermore, all of the obtained experimental and FEA results are in good agreement with each other.