Fire, by its nature, is a stochastic phenomenon which introduces a great deal of variability to the development of fire incident. In the case of analysis of wooden structures, the uncertainties pertaining to the properties of the structures are inherent, most especially the mechanical response of the glulam beam and the charring rate. Computer program is presented for a probabilistic design of glulam beams when exposed to fire in accordance with Eurocode 5(2004). This was achieved by considering the strength of the member in bending, lateral stability and shear. The randomness of the design process was achieved by the use of First Order Reliability subroutine which was in-built into the design process. Three failure modes of bending, lateral stability and shear were considered at a target safety of 3.0. It was shown that considering bending and lateral stability failure criteria the safety index of beam considering grade GL20 reduced by about 80%, by about 96% for grade GL24, by 82% for grade GL28, by about 73% for grade GL32, and by about 66% when GL36 was considered. However, considering shear condition for GL20/24 the safety index reduced by about 82%, reduced by 79% for GL28 and by 74% for GL32/36. It was also shown that the lateral stability condition is more effective at 30 minutes of fire exposure, the bending condition is more effective at not more than 60 minutes of fire exposure, while the shear condition is effective up to 90 minutes of fire exposure. Shear failure was therefore shown to be the safest of the three failure conditions considered, while the lateral stability condition was the most critical condition for the design of these beams when exposed to fire.
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