Abstract
In wood structures, the elements subjected to bending stresses, such as the beams, present a fracture initiated in the tensile region, and under these conditions, the use of laminated composite materials is presented as an alternative solution in the form of repair or reinforcement. This research aimed to evaluate the influence of the use of carbon fibers laminated composites in tensile reinforcement in the direction parallel to grain of Pinus elliotti and Manilkara huberi wood species. The Viapol two-component epoxy adhesive was used in the lamination and fixation of the unidirectional carbon fiber in the wood species. Ten specimens with no defects (reference) and 10 specimens were prepared for each crack length (25 and 50mm) with and without the reinforcement (60mm × 50mm) by the laminated composite. The tensile tests were performed in accordance with the requirements of the Brazilian standard ABNT NBR 7190 (1997). From the results of the statistical analysis, the use of the carbon fiber composite was able to restore the tensile strength of the cracked samples (partial or total) in relation to samples without defects, demonstrating the potential of the laminates in carbon fibers as an alternative solution in repair for both wood species.
Highlights
An alternative to repair or reinforce wood structures, among other materials, consist on the use of composite materials (Bertolini et al 2014, Miotto and Dias 2015, Carvalho et al 2016, Fernando et al 2016), laminates of carbon fibers (Fiorelli and Dias 2003, Garcia et al, 2013), because they have elevated mechanical strength and can contribute significantly in tensioned regions of structural elements of wood subject in bending, elevating its tensile strength and stiffness, since bending failure begins by tension. (Franke et al 2015, Grazide et al 2015)
Ten (10) specimens with no defects and 10 specimens were prepared for each crack length (25 and 50mm) with and without the reinforcement (60mm length × 50mm width) by the laminated composite fixed on both sides (Figure 2c), resulting in five distinct experimental treatments (Tr) (Table 1) and a total of 50 test specimens in all for the tensile tests
The mean value of the tensile strength parallel to the fibers of Pinus elliotti obtained in the present study is equal to 73,38 MPa, with mean confidence interval (CI) equal to CI = (60,72; 86,03 MPa)
Summary
The timber structures, if not properly treated for physical and biological attacks, such as climate change, moisture change, can present problems such as cracks, which may compromise the purposes for which they were designed (Dias and Lahr 2004, Christoforo et al 2017, Sander et al 2017). The problems caused by biological and physical attacks on wood structures due to moisture change and the effect of long-term load on timber creep, such as cracks and great deflection on structural parts, may be Maderas. Universidad del Bío-Bío explained by the natural source and behavior of wood, compromise the use of running structure and safety conditions for users (Franke et al 2015, Fernando et al 2016). An alternative to repair (recovery of the original load capacity of the undamaged element) or reinforce (increase of the original load capacity of the undamaged element) wood structures, among other materials, consist on the use of composite materials (Bertolini et al 2014, Miotto and Dias 2015, Carvalho et al 2016, Fernando et al 2016), laminates of carbon fibers (Fiorelli and Dias 2003, Garcia et al, 2013), because they have elevated mechanical strength and can contribute significantly in tensioned regions of structural elements of wood subject in bending, elevating its tensile strength and stiffness, since bending failure begins by tension. (Franke et al 2015, Grazide et al 2015).
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