Residual area method for heat transfer analysis of concrete-encased I-sections in fire

Zhi Hua Wang, Kang Hai Tan

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


A design concept called the residual area method is proposed to calculate the equivalent thickness of concrete for temperature analysis of concrete-encased I-sections in fire. The design of the equivalent concrete thickness is based on a regression analysis which is verified by experimental results. The significance of the coefficients of the regression analysis is assessed through statistical means (R2 values and F-tests), and shown to be reasonably satisfactory. The steel temperature response of concrete-encased I-sections subjected to fire is characterized by three temperature variables. The proposed method makes use of the EC 3 provisions to formulate the temperature response of each representative point along the steel profile using a 1D heat transfer model. Apart from standard fire conditions, the proposed method is applied to concrete-encased I-sections exposed to hydrocarbon, external and parametric fire curves. The results demonstrate that the residual area method is intrinsic to the geometric configurations (cross sections) of concrete-encased I-sections, but independent of heating conditions. The proposed method has been further verified by three series of specimens, and the predictions are compared against the results obtained from finite element analysis.

Original languageEnglish (US)
Pages (from-to)411-422
Number of pages12
JournalEngineering Structures
Issue number3
StatePublished - Feb 2006
Externally publishedYes


  • 1D analysis
  • Concrete-encased
  • Fire
  • Heat transfer
  • Regression
  • Residual area

ASJC Scopus subject areas

  • Civil and Structural Engineering


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