。In using a parametric Load-bearing resistance curve the concept known as‘equivalent Standard fire Natural fire time'can be used both to compare the severity of the fire in consistent terms and Time Temperature Fire severity time-equivalent to relate the resistance times of structural Compartment temperature elements in a real fire to their resistance in Element temperature the standard fire. Fire resistance ime time-equivalent Figure 9.2 Time-equivalent severity of natural fires• In using a parametric curve the concept known as ‘equivalent time’ can be used both to compare the severity of the fire in consistent terms and to relate the resistance times of structural elements in a real fire to their resistance in the standard fire. Figure 9.2 Time-equivalent severity of natural fires