Experiments were conducted on beams with openings spaced at different intervals along the web. It was observed that the OSB fractured from tension zones around an opening, with cracks developing diagonally towards the beam flanges. A beam would collapse when the cracks reached the flanges. Interactions between openings further reduced the load carrying capability of a beam and changed its failure pattern. Using ABAQUS, Finite element models were developed to simulate beam behaviour. Material nonlinearity, fracturing of OSB, crack propagation and beam failure were dealt with by a user subroutine. Good correlation was obtained between test and analytical results. Critical distances between openings were also investigated.