Fatigue Behaviour of LVL Subjected to Repeated Shear Stresses.

Abstract: The fatigue behavior of laminated veneer lumber (Douglas-fir) subjected to shearstress has been studied. The static shear strength of specimens, 37 by 102 by 406 mm was established through a three point bending test over a span of 305 mm. Four series of specimens were subjected to a cyclic load history with peak loads ranging from 95 to 80 percent of the static strength. The duration of each load cycle was approximately 32 seconds. A stress-level verses (log) number of cycles diagram was produced to show the fatigue behavior. The load-level was calculated from the static strength using the assumption of equal rank. A least square regression analysis was made and was found to fit the S-N data well. The lowest load-level tested in this research was approximately 70 percent. At this load-level the specimen survived close to 3000 cycles.