Equivalent concrete layer thickness of a fire protection insulation layer

The reinforcement bars in a concrete structure are usually protected against fire only by the concrete cover layer. In some cases an additional protection is needed and hence protective layers are applied, which consist of light-weight insulation materials. The theoretical analysis outlined in this paper shows that: (a) the thermal protection capacity of a protection layer can indeed be expressed as an equivalent concrete layer; and (b) a simple relation can be established between the thermal resistance (R=delta/k) of the protection layer and the thickness of an equivalent concrete protection. The equivalent concrete thickness yields the same time for reinforcement bars to reach 500 degrees C as the corresponding thermal protection layer when the structure is exposed to the standard ISO 834 fire. All the analyses have been carried out with the finite element temperature analysis computer program TASEF. Copyright (C) 1996 Elsevier Science Ltd.