Timber members appear in structural assemblies unprotected or protected by a fire protection
system. Mostly passive fire protection systems are used which have the ability to delay the start of
charring and decrease the charring rate as long the fire protection is attached to the structural element.
Together with the failure time of a fire protection system the start of charring and the charring rate are
crucial parameters for the residual cross-section which is the dominating parameter for the load-bearing
capacity assessed in fire tests or calculation models as given in Eurocode. Calculation models are
requested since they allow the variation of building components and are cost effective compared to fire
tests. However, the accuracy of the load-bearing prediction under standard fire exposure is highly
depending on the input factors (start of charring, failure of the protection system and charring rate) for
the calculation of the residual cross-sections. Today no practical system is available to determine these
input factors for fire protection system.
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