Requirements for lining thickness is determined based on U/A – massiveness indicator of fire, which is calculated on the basis of:
You- circumference of the steel beam
A – the cross-sectional steel profile
In principle, when the circuit and cross-sectional area of the steel profile have the same dimensions of their solidity ratio is very low. In contrast to the thin-walled profiles – then ratio U / A is very high ( quickly reaches a temperature 500 degrees). In such cases the use of thicker linings. On the basis of the index table is read d – ie the thickness of the cladding suitable for a particular class of fire resistance.
Poniżej present for the calculation of the U / A for specific steel structures.
How to calculate U / A in specific cases?