Theoretical and experimental study of glulam beam reinforced with glass fiber

Author(s)

Juliano Fiorelli

• Document type: Doctoral Thesis
• Press: São Carlos.
• Institution: Universidade de São Paulo (USP). Instituto de Física de São Carlos (IFSC/BT)
• Defense date: 2005-04-25

Examining board members

Antonio Alves Dias; Carlito Calil Junior; Jose Nivaldo Garcia; José Antonio Matthiesen; Almir Sales

• Advisor: Antonio Alves Dias

Abstract

Glulam beam is used in countries of North America and Europe. In Brazil, the technique exists since the 20th Century, but its use is incipient in relation to the possibility of the product. The development of products that use wood with small dimensions is important to eliminate defects in the structural pieces, such as knot and marrow, which reduce the strength and stiffness of the piece. The increase of the strength and stiffness of the glulam beam can be achieved through the classification of the lumber, or by an appropriate disposition of the lumber. Another way to obtain an increase in the strength and stiffness of the glulam beam it is the use of fiber reinforced polymers (FRP). This way, besides improving the mechanical properties of the structural element, increases the reliability in relation to the rupture way. This work establish criteria for production of glulam beams, without and with reinforce of glass fiber, starting from information obtained in the bibliographical revision, approaching aspects related to the straight of the wood (species and quality of the wood, inclination of the fibers in relation to the longitudinal axis of the pieces, marrow presence), dimensions of the sheets, minimum spacing between bitten amendments of a same sheet and positioning of the jagged amendments in the beam. A numeric model for calculation of the straight moment and flexural stiffness (EI) of glulam beams was proposed. The model admits the validity of the hypothesis of lineal distribution of deformations along the height of the beam, elastic-fragile-lineal behavior of the wood in the parallel traction and bi-lineal in the parallel compression of the fibers. This model was implemented in a computer program that uses an interactive process to determine the value of the straight moment and of the flexural stiffness. Experimental results obtained indicate the validity of the theoretical model proposed. A test of delamination was done to evaluate the efficiency of the adhesives Phenol-resorcinol and Epoxy AR-300 when submitted to temperature, humidity and pressure variation. Results indicated the efficiency of these adhesives. (AU)