Fire resistance design of unprotected concrete filled steel hollow sections: Meta-analysis of available furnace test data

Concrete filled steel hollow structural sections are an efficient, sustainable, and attractive option for both ambient temperature and fire resistance design of columns in multi-storey buildings and are increasingly common in modern construction practice around the world. Whilst the design of these sections at ambient temperatures is reasonably well understood, and models to predict the strength and failure modes of these elements correlate well with observations from tests, this appears not to be true in the case of fire resistant design. This paper assesses the statistical confidence in available fire resistance design models/approaches that are used in North America and Europe by performing a meta-analysis which compares the available experimental data from large-scale standard fire tests performed around the world against fire resistance predictions from design codes. It is shown that available design approaches carry a large uncertainty of prediction, suggesting that they fail to properly account for fundamental aspects of the underlying mechanics during fire. Current North American design approaches for CFS columns are shown to be considerably less conservative, on average, than those used in Europe.