Design model for the verification of the separating function of light timber frame assemblies

In order to limit fire spread by providing adequate fire compartmentation, elements forming the boundaries of fire compartments are designed and constructed in such a way that they maintain their separating function during the required fire exposure (insulation and integrity criteria). While fire tests are still widely used for the verification of the separating function of light timber frame assemblies, design models are becoming increasingly common. A comprehensive research project on the separating function of light timber frame wall and floor assemblies with cladding made of gypsum plasterboards and wood-based panels was carried out at ETH Zurich in collaboration with the Swiss Laboratories for Materials Testing and Research (Empa). The objective of the research project was the development of an improved design model for the verification of the separating function of light timber frame wall and floor assemblies. A large number of small-scale fire tests permitted the analysis of different parameters on the thermal behaviour of protective cladding made of gypsum plasterboards and wood-based panels. The results of the fire tests allowed the verification and calibration of thermal properties used for thermal finite element (FE) analysis. Based on an extensive FE parametric study, the coefficients of the design model for the verification of the separating function of light timber frame wall and floor assemblies were calculated. The design model was verified by means of full-scale fire tests. The paper first describes the basic structure of the design model for the verification of the separating function of light timber frame wall and floor assemblies. Then, the main results of experimental and numerical analyses are presented. The results permitted the calculation of the coefficients of the design model for the verification of the separating function of light timber frame wall and floor assemblies.