In this study, the structural behavior of medium-density fiberboard (MDF) beams reinforced by unidirectional glass fiber-reinforced thermoset polyurethane outer layers is investigated by conducting beam bending and vibration tests followed by a parametric study. First, the MDF material properties are determined by 3-point bending and cantilever beam vibration tests. Then the same tests are conducted on the composite sandwich beam specimens produced by hand layup technique and the level of increase in overall stiffness and the ultimate failure loads are determined. The experimental results obtained are found to be in good agreement with the analytical results and the numerical results obtained using a 1D shear deformable beam model. Finally, a parametric study is conducted to determine the influence of FRP reinforcement for different span lengths and fiber volume ratios. The results obtained from this study show that reinforcing MDF beams by FRP outer layers may considerably increase the flexural stiffness for all span lengths but the ultimate failure load may not be increased for short span lengths due to core shear failure, especially when there is no constraint on maximum displacement.
