Effect of hole location on the load-carrying capacity of laminated veneer lumber (LVL) beams

Predicting load-carrying capacity of timber beams with holes requires a model capable of accounting for the microscopic material behaviour that influences crack initiation and propagation. The complex stress distribution around the periphery of a hole causes additional tension perpendicular to grain stresses which can change the failure mode of the beam. This situation can also be affected with a change of hole location within the beam depth because stress intensity factor will be increased by tensile stresses and decreased by compressive stresses. This is not an unlikely situation as services often have to pass through beams at different depths. This paper investigates the effect of changing the hole location through the depth of Laminated Veneer Lumbers (LVL) beams utilising an experimental and numerical investigation. Experimental tests to failure of LVL beams and numerical simulations using finite element methods have shown that for a hole eccentricity of less than 20% of the beam depth, the load-carrying capacity of the beam did not change significantly. The numerical method showed that for the three-point loading condition the hole location along the beam length did not affect the failure load of beam as long as the hole was located at a distance of at least the beam depth from the supports and from the concentrated load. For uniformly distributed loading, a linearly decreasing stress intensity factor from the support to mid-span was exhibited, showing an increase in load-carrying capacity as the opening approached mid-span.