Experimental investigation on dowel laminated timber made of Uruguayan fast-grown species

Abstract

This paper presents the experimental results on Dowel Laminated Timber (DLT) made of Uruguayan fast-growing Pinus elliottii and Eucalyptus grandis, fastened with hardwood dowels. Four series, each comprising six structural-size panels made of different combinations of lamella species and dowel diameters were constructed and tested in 4-point bending. The strength and stiffness of panels made of eucalyptus lamellae were superior to those of pine, regardless of dowel species or dowel diameter. These results are consistent with the superior density and stiffness values found for eucalyptus lamellae (475 kg/m3, 10,57 kN/mm2) compared to the respective values for pine (399 kg/m3, 5,37 kN/mm2) previously determined by NDT (non-destructive testing). Moreover, the bending strength of pine DLT were significantly higher (19,82 and 16,84 kN/mm2) than the strength of the lowest grade of sawn pine timber (11,01kN/mm2) established in the Uruguayan Standard UNIT 1261. Species of dowels, evaluated on pine DLT, did affect the strength but not the stiffness of the panels. Diameter of dowels, analysed on eucalyptus DLT, showed no influence on the mechanical properties of the panels. Failure type observed in tested specimens suggests that joint between lamellae and dowels performed correctly