ABSTRACT

The design of concrete elements affected by exposure to fire may be undertaken in one of two ways; a prescriptive approach or a calculation approach. The prescriptive approach, in which tables of minimum dimensions, minimum axis distance. Design codes frequently place restrictions when high covers are needed at high fire resistance periods in order to maintain low temperatures in the reinforcing. A concrete with a high moisture content is more likely to spall since one of the possible mechanisms of spalling is due to the build up of high vapour pressures near the surface causing tensile failures in the concrete caused by moisture clog. The mechanical response or resistance of any concrete element so exposed will need calculation during the early stages of the cooling period as the critical design strength may be attained after the maximum fire temperature has occurred.