Mechanical performance of glued-laminated timber beams symmetrically reinforced with steel bars

The technology of glued laminated (glulam) timber has enabled the design of composite structures with large dimensions. The laminations are generally derived from the sawing of small trees and species of rapidly growing, which yields laminates with low mechanical properties. This study evaluates the benefits of the reinforcement of glulam beams, by employment of steel reinforcement ratios of 2% and 4%. In the beams with a ratio of reinforcement of 2%, in relation to the unreinforced glulam beams, the stiffness increased approximately 52% and the serviceability load increased 53.1%, and with the employment of steel ratio equal to 4% these increases were in the order of 73% and 79.2%, respectively. The results showed that the insertion of steel bars can reduce the inherent variability of wood and increase significantly the stiffness of glulam, which consequently increases the beam capability for serviceability limit states.