Wooden trusses using metal plate connections and fabricated with Gmelina arborea, Tectona grandis and Cupressus lusitanica timber from forest plantations

The present work aims at determining the behaviour relative to load applied and displacement and the design values of Howe trusses 7.2 m long fabricated with timber from Gmelina arborea, Tectona grandis and Cupressus lusitanica, using metal plates. The static flexural strength of the trusses was tested by applying the load to three different points, determining the load and the displacement at the central point of the truss, and then these values were used in the SAP2000 program, to define the design values. The results showed design loads at 5.00 kN, 6.34 kN and 5.52 kN and displacements at 1.53 cm, 1.27 cm and 1.71 cm, for trusses fabricated with G. arborea, T. grandis and C. lusitanica timber, respectively. As for the design tables, the values of maximum load diminished with increase in support spans (with 5 m, 6 m, 7 m and 8 m simulated support spans). The load ranged between 59.05 and 186.21 kg/m for G. arborea, 91.38 to 286.39 kg/m for T. grandis and 57.45 to 183.35 kg/m for C. lusitanica. Although truss manufacturing with the three species is viable, T. grandis showed the highest potential.