Simulation of Load Carrying Capacity of Sheathed Parallel Timber Beam Structure

A study on the load carrying capacity of a sheathed parallel timber beam structure taking into account load sharing between timber beams is presented. Monte Carlo simulations are used to generate systems and to evaluate the influence of different parameters on the system behaviour. The variability in bending strength within and between timber elements is accounted for using a model by Isaksson (1999). A tri-linear load deformation relationship is used giving the beam a reduced load carrying capacity after initial failure. Experiments indicate that system failure can be defined to occur when two beams next to each other or any three beams fail. The properties of the sheathing are assumed to be deterministic and the stiffness of the joint between beam and sheathing is varied. The simulations give the load capacity for the weakest beam in the system (with no load sharing and no capacity of the beam after initial failure) and for the system failure. The results show a 19-30 % increase in load capacity for the full model with load sharing compared to a system where the weakest beam with no load sharing defines the load capacity. The failure mode considered is bending failure in the solid timber beam.