BENDING STIFFNESS AND RESISTENCE OF STRUCTURAL GLULAM BEAMS AND I – JOIST COMPOSED OF DIFFERENT ADHESIVES
DOI:
https://doi.org/10.5902/198050981857Keywords:
glulam, I – joist, potential adhesives for beams.Abstract
Wood has always been structurally used in solid form in civil construction, with a low degree of processing and technological innovation, and many times in other constituents such as floors, walls and roofs. However, changes in the adopted standards involve the refinement of technology, as well as, changes of the esthetic and functional concepts required in constructions. Thus, structural wood beams, such as glulam and I – joist, have emerged, presenting a series of advantages such as high resistance in relation to weight. The general objective of this study was to evaluate the effect of the type of adhesive on the strength and stiffness of beams of Glulam and I-joist of Pinus taeda. The adhesives used in the experiment were resorcinol-phenolformaldehyde (RFF), melamine-urea-formaldehyde (MUF) and polyurethane (PUR). The process of manufacturing the beams involved the classification of the parts, manufacturing of the finger joint, junction, assembly and pressing. The assays involved the assessment of structural properties of bending such as the Elasticity Model and Rupture. In the analysis of the average values for the variables, no significant differences were found for the glulam, however, for the I - joist, the superiority of the PUR adhesive was verified, based on the average value of the rupture model. In relation to the types and weights of the adhesives used, it was observed that the RFF adhesive needed a greater amount of the product to provide the mechanism of adherence, 500 g/m2. Two parameters made the PUR adhesive different in relation to the others: a 24 times faster healing time, making it more advantageous from the point of view of volume of production; and the shorter open time, which requires special procedures. The glulam beams showed higher mean values, but the choice of the beam model must be analyzed carefully, always taking into consideration the required resistance and the cost of the material to be used in the confection.
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