Parametric experimental study on GLT columns stability during natural fire tests including the cooling phase

This paper is about the behaviour of glue laminated timber (GLT) columns subjected to physically based fires which include a decay phase. A summary is first given of the results of numerical analyses, of furnace tests made in a controlled environment following the parametric fire model of Eurocode 1 and of a series of seven tests made in a naturally vented compartment with wood cribs used as fire load.
This paper then presents in detail the results of five additional tests performed in the same fire compartment with some variation of the parameters compared to the previously presented series. One test conducted with the same 280 × 280 mm² section as the previous series but with lower compartment temperatures, led to collapse after 45 minutes, not yet in the decay phase. Three tests were made on an increased section of 400
× 400 mm². These three specimens survived for more than 11 hours but collapsed thereafter due to localised zones of increased charring and combustion, essentially at the base of the columns. The final test investigated the effect of fire service intervention. In this test on the 280 × 280 mm² section, the column did not collapse owing to the intervention of fire fighters after 35 minutes of fire.