Ignition, Charring and Structural Performance of Laminated Veneer Lumber
Degree GrantorUniversity of Canterbury
This report describes the results of an investigation into the fire performance of laminated veneer lumber (LVL), considering both the early fire hazard and the structural fire performance as well as to develop design methods for the structural performance of LVL beams and columns exposed to post flashover fires. To determine ignition properties cone calorimeter tests were undertaken at heat fluxes varying from 10 to 50 kW/m2 , the time to ignition was recorded for each heat flux and for the orientation of the grain being exposed. To determine charring rates cone calorimeter tests were carried out on blocks of LVL with a number of grain orientations, each for a range of heat flux exposures. Instrumented samples incorporating embedded thermocouples were used to locate the char front within the sample. Char rates found from the instrumented tests were confirmed on subsequent tests of un-instrumented samples that were subjected to the same heat fluxes but for selected exposure times. Charring experiments were also carried out on three LVL beams, approximately 100 x 300 mm in cross section and 2 m long, tested in a pilot scale furnace following the ISO 834 standard fire curve. Embedded thermocouples were used to record layer temperatures, which were then used to calculate the residual cross section for prediction of structural behaviour in fire conditions. A load-bearing fire resistance test was carried out on a larger LVL beam spanning 4 m in a full size furnace, following the ISO 834 standard fire curve. The report concludes by including design recommendations for a simple method for predicting the fire performance of radiata pine LVL exposed to post-flashover fires.