Fire Resistance Design of Unprotected Concrete Filled Steel Hollow Sections: Meta-Analysis of Available Furnace Test Data

Abstract

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.

Structural performance of unprotected concrete-filled steel hollow sections in fire: A review and meta-analysis of available test data

“…The EC4 Annex (CEN 2005) database contains 76 tests, with a good distribution section size, concrete strength, infill type, and load ratio, but a limited range of end restraint conditions, effective length, and initial load eccentricity. A full summary of the specific tests used in the analysis presented herein is presented elsewhere (Rush et al 2011) 8. Implementation of the code-specified approaches…”

Circular Concrete-Filled Tubular Columns: State of the Art Oriented to the Vulnerability Assessment

“…i) The first approach is limited to a small number of cases and provides minimum cross-sectional dimensions that a CFT must have for the sake of achieving a standardized level of performance. Authors such as Rush [69] in his reviews of the methods for the calculating the fire resistance of CFT pinpoints the potential level of unsafety the usage of such tables may lead to.…”