Fire resistance of 19th century fireproof flooring systems: A sensitivity analysis

Typical fireproof flooring systems of the 19th century comprise of metal beams embedded within insulation materials that span between them, sometimes in the form of arches. The limited or non-existent fire resistance requirement of that era demands a thorough understanding of their structural fire response when dealing with their conservation. This requires suitable material property models. Historical records from different sources contain large variations in the thermal (insulation and metals) and mechanical (for metals) properties of the materials. In this research, the variations were placed within lower and upper boundary curves. A sensitivity study of the thermal behaviour of typical flooring systems was conducted. The results of this study were used to indicate the level of uncertainty in the thermal properties of the metals (cast iron, wrought iron and mild steel) and the “insulation” materials (“early concrete” and masonry) that may be tolerated without introducing large inaccuracy (>10%) in the structural temperature results. To assess the applicability of the proposed boundary curves for the mechanical properties of the metals, the second series of sensitivity analyses of structural performance was performed, using the temperature profiles from the thermal sensitivity study.