FIRE PROTECTION OF TIMBER MEMBERS-DETERMINATION OF THE FIRE PROTECTION SYSTEM CHARACTERISTICS FOR THE VERIFICATION OF THE LOAD-BEARING RESISTANCE BY MEANS OF CALCULATION MODELS

摘要

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.