"I-Beams made from Slash Pine flanges and either hardboard or particleboard webs were fabricated and evaluated for flexural stiffness. Prior to fabrication the web and flange materials were evaluated for flexural stiffness. In addition the rupture strength in tension of the web materials was determined. From these data a mathematical model was developed for the stiffness of a composite I-Beam. It varied from the classsical rigidity model which is based on the product of stiffness and second moment of area (EI). The effect of holes in the web was evaluated. The essential ingredient is the magnitude of shear force at the point at which a hole can be made. Assuming a uniformly distributed load on the beam, a large circular hole can be drilled where the shear force is zero. Smaller holes can be drilled in proportion to the increase in shear force."--p. (i).