The traditional approach in order to estimate the structural response to fire is by mean of prescriptive methods, based on parametric time-temperature curves. These mathematical laws should approximately describe the global behavior of the structural members when fire is occurring. Despite this method is much faster and simpler than the engineering-based one, it does not take into account of many relevant aspect, such as the geometrical features, the chemical reaction of the combustion and the position of the fire, that cannot be considered in a rigorous way. Several curves have been implemented by the current standards, in order to state the minimum requirements to satisfy security checks when the structure is subjected to fire.