Energy based time equivalent approach for evaluating fire resistance under design fire exposures

This paper presents the development of an energy based approach for evaluating equivalent fire resistance of reinforced concrete beams under design fire exposures. The method is based on principle of equivalent energy and estimates equivalent fire resistance by comparing energy transferred under design and standard fire exposures. The validity of the method is established by comparing predictions from the proposed approach with those obtained from other time equivalent methods, empirical formulae and with non-linear finite element (FE) analysis. Based on the results, a correlation is proposed to relate the equivalent fire resistance with maximum temperature of design fire. It is shown through comparison, with existing approaches, that the proposed method is capable of predicting time equivalent with an accuracy that is sufficient for practical purposes.