Structural behaviour of glued laminated timber beams pre-stressed by compressed wood

In this study, glulam beams were strengthened by inserting compressed wood (CW) blocks into the pre-cut rectangular holes with one-thirds of the beam depth from the top of the beams. This practice was to make use of moisture-dependent swelling nature of the compressed wood which was conditioned with the moisture content significantly lower than the ambient one. The test results showed that a pre-camber was produced in the mid-span of the beam reinforced due to expansion of the compressed wood blocks on the top part of the beam. As a result, significant initial tensile and compressive stresses were generated on both the top and the bottom extreme fibres of the beam, respectively. Subsequent bending tests revealed that the initial stiffness and load carrying capacity of the pre-stressed beams were increased significantly in comparison to the beam without pre-stressing.

▸ A new approach to strengthen glulam beams has been established by using compressed wood. ▸ The pre-stressing technique has been approved to be effective with significant pre-camber. ▸ The techniques developed are simple, economical and environmental friendly. ▸ There are significant enhancements on the bending capacity and the initial stiffness. ▸ Very good compatibility as using timber to pre-stress timber.