Glued laminated timber beams reinforced with sisal fibres

The current appeal for sustainable building materials has expanded the use of timber in construction. However, due to timber be a raw material, natural defects are present, what reduce its strength capacity and cause, in particular, brittle failures in the tensile region of timber beams. In order to increase the mechanical properties of these beams, fibre reinforcement can be applied. In this context, natural fibres, such as Sisal fibres, already used in various fields of construction, are an alternative for reinforcement of timber structural elements, by taking into account their adequate mechanical properties and, in special, for low-mechanical resistance wood species, such as Pinu sp, a species used widely in timber construction. This paper deals with an experimental analysis glued laminated timber beams (Glulam) of Pinus sp species, reinforced by Sisal fibres. Bending tests were performed on six beams with the following dimensions, 53 mm-width by 180 mm-height by 3000 mm-length, which were prepared with eight lamellas by 8 mm-thickness. These beams were reinforced with Sisal strips that were glued by Epoxy adhesive on the bottom part of these beams. In addition, comparisons of result with non-reinforced Glulam were carried out. From the analyses of the experimental results, a decrease of 20 to 30% for the normal stresses, 5 to 10% for the shear stresses and 8 to 12 % for the displacements in relation to non-reinforced beams were verified8439039

Experimental investigation of glued-laminated timber beams with Vectran-FRP reinforcement

The growing interest in sustainable buildings has inspired the improvement of timber structures in the construction market. As a raw material, wood may present natural defects that can cause changes in its mechanical properties, such as strength reduction, as well as brittle failure under tension, which limit the application of this material in construction. In recent decades, synthetic fibers with high tensile strength are available as construction material, and research to evaluate the efficiency of synthetic fibers and adhesive composites as a reinforcement for glued-laminated timber beams has been carried out. This paper deals with an experimental study applying bending tests to glue-laminated timber beams made of Pinus Elliottii, a low-strength wood class originated from reforestation, and strengthened with fiber reinforced polymers of Vectran fibers and epoxy adhesive. A numerical procedure based on the finite element method is also developed to compare with experimental results. Vectran is a synthetic thermoplastic fiber with high mechanical properties, however, its potential application as reinforcement material in structural pieces is still poorly explored. The results obtained in this work demonstrated that the application of Vectran-FRP reinforcement to glued-laminated timber beams provided both an increase of 19.48 to 34.95% in elastic regime stiffness and of 7 to 40% in ultimate load, when compared with unreinforced similar beams. Numerical analysis adequately confirmed the experimental results on elastic behavior, while in the non-elastic phase it revealed a considerable difference. A reduction in the rupture coefficient of variation regarding the reinforced beams was also verified. In addition, the application of fibers as structural reinforcement changed the timbefs failure mode from brittle in tension to ductile in compression. The results show that Vectran fibers are mechanically efficient as reinforcement, with perspectives of application in construction202CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQBrazilian National Council for Scientific and Technological Development (CNPq)National Council for Scientific and Technological Development (CNPq); University of Campinas (UNICAMP); School of Civil Engineering, Architecture and Urban Desig