Calculation of parametric temperature curve
The fundamental problem of the fire resistance analysis is the determination of the design fire model (dependency of gas temperature on time). The available options are described in the standard EN 1991-1-2 (Actions on structures exposed to fire). This standard contains basic models represented by nominal curves, simplified methods and advanced fire models. Problems of more complicated models are the difficulty of calculations and obtaining of adequate analysis parameters. The usage of nominal temperature curves is easy and efficient. However, results may be inaccurate, mainly for long lasting fires. The nominal curves, contrary to parametric curve, don't contain cooling phase, i.e. the reduction of gas temperature after burning all fire load. Another advantage of the parametric curve is that it takes into account the compartment size, size of openings in walls, structure materials, type of occupancy and active fire fighting measures.
The validity of parametric temperature curve is limited by the maximum floor area 500m2 and the maximum wall height 4m. The ceiling can't have any openings.
The calculation of curve course is performed according to the Annex A of EN 1991-1-2.