Fire endurance of laminated veneer lumber

Laminated veneer lumber (LVL):(Douglas-fir ((Pseudotsuga menziesii France)) and larch ((Larix gmelinii Kuzeneva))) with joints were tested to learn th e fire resistances. The maximum rate of deflection described in the Notific ation No. 1454 of the Ministry of Construction (or the limiting rate of def lection of ISO 834) were appropriate for the fire endurance of LVL beams, t he same as the eye measurement. The fire endurence prediction of no-joint L VL were calculated with the bending coefficient of the load lists correspon ding to the allowable unit stress for long sustained loading of LVL of the Japanese Agricultural Standard (JAS). Three joints showed good fire perform ance in order of drift pin joint with insert-type steel gusset plate, lag b olt (lag screw) joint with up and down faces gusset plate, and bolt joint w ith side gusset plates. All steel plates, lag screws, and bolts were covere d with 25 mm thickness wood. The fire endurances showed that the drift pin type was the best for practical use, good performance for the design, and t he execution of work. Charring rates of Douglas-fir and larch LVL were 0.6- 0.7 mm/min and agreed with that of glued laminated timber, so that these sh owed the same performances in fire as a heavy timber.