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 Engineering Symposium (IES’20), İzmir, Turkey, 5 - 13 December 2020, pp.209-214

  • Publication Type: Conference Paper / Full Text
  • City: İzmir
  • Country: Turkey
  • Page Numbers: pp.209-214

Abstract

The fire performance of the structures has been subject of research interest over the past decades. To date, there exist many research works on the topic of structural analysis of building elements under the fire load. Whilst many of these studies are identifying fire behavior of structures from mechanical and material perspectives, but they remain narrow when it comes to determination of dynamic characteristics of fire exposed structural members. Within this scope, the 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 a far more feasible alternative in comparison to the 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 modal behavior of reinforced concrete (RC) column, as one of the most important load-bearing elements of the buildings. Afterward, FEA has been used to confirm the results obtained experimental stage. Initially, an experimental fire furnace test was conducted over an RC column with a height of 1.5m and a square cross-section of 0.2m. Besides, the dynamic characteristics of the test specimen have been recorded both before and after the fire test. To measure the dynamic characteristics, Operational Modal Analysis (OMA) method has been conducted. 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 the modal analysis of RC columns under the fire load. The ISO 834 standard fire curve with an exposure duration of 3 hours has been used for both experimental and FEA. From the results it was observed that temperature increases reduce the natural frequency of the RC column. In addition, the mode shapes of the RC column are also affected by elevated temperature. However, no specific pattern could be obtained explaining the changes in mode shapes of the RC column under the fire load. Furthermore, all of the obtained experimental and FEA results are in good agreement with each other.