BEHAVIOUR OFSTRAIGHT GLULAM BEAM WITH SCARFAND BUTT JOINTS - PART II

ABSTRACT

The objective of this research was building and testing eight 5.4 meter long glulam beams, using Pinus spp and Eucalyptus cifriodora lumber for the laminations. Four of them were made of pine wood only and the others of pine plus eucalypti. Plies were made longer by using scarf joints in the tension side and butt joints in the compression side of the beams. In the pine beams, these joints were glued simultaneously with the gluing of the plies, thus eliminating a previous adhesion. In two beams with pine-eucalypti woods, the adhesion was previously made. The beams were loaded to rupture and described as to their modulus of rupture and type of fracture. Modulus of rupture average 55.6 MPa and 70.7 MPa for the first (pine) and second group (pine-eucalypti), respectively. The differences between the experimental and the theoretical modulus of elasticity amounted to only 4.1% and 3.5 % for pine and pine-eucalypti beams, respectively. The addition of the Eucalyptus cifriodora plies increased the modulus from 11,305 MPa to 18,382 MPa. Of the four pine beams tested, two failed in the joint most stressed in tension. In the beams with eucalypti wood, the border laminations that were glued and jointed separately, did not presented compression and tension failure. This seems to indicate that these joints should be made in a previous operation.

Key words:
glulam; pine; eucalypti