Experimental and numerical analysis of the unreinforced and reinforced notched timber beam by a screw

Abstract

Timber is highly anisotropic. It behaves differently in diverse directions. Tension and compression perpendicular to the grain present a low strength with respect to the ones parallel to the grain. To compensate for the lack, the self-tapping screw is an excellent choice for reinforcing the timber. This paper focuses on the notched timber beam with the experimental and numerical results. In the first part, the experimental results of the unreinforced notched beams and the screw reinforced notched beams under bending load will be presented. The second part describes a numerical study in which a 3D finite element (FE) model and a fast FE model of the notched beam reinforced by a self-tapping screw are realised. In particular, the fast FE model is simplified with the use of the screw’s model as a beam element having one translational degree of freedom. This model not only presents a good result in comparison with the experiment as well as the 3D FE model but also requires six times less computational times as compared to the 3D FE model.

Nonlinear Finite Element Modeling of Wooden Elements Strengthened by FRP

“… Definition of material properties of wood and fibres regarding modulus of elasticity and Poisson's ratio in three orthogonal directions. Hill criterion for material strength determinations in pertinent directions is employed [9,19,20]. Adhesive properties are delineated through use of cohesive elements [21].…”

“…In case of disparities, adjustments were made to material properties or the model parameters, thus enhancing the model's precision. For validation, two models were made for wooden beams tested experimentally in two previously published researches [20,21] illustrated in Figures 5 and 6. One of these models was a solid wooden beam, while the other incorporated fibre reinforcements.…”

“…A three-dimensional numerical model was made for a solid beam previously tested by Tran et al [20], having dimensions 900 x 100 x 80 mm, following the outlined steps. The created model employing 3D deformable/solid/extrusion format for wood, and for bottom steel plate 50 x 50 x 80 mm, the model was also in a 3D deformable/solid/extrusion format.…”

“…The Quads Damage option within the software facilitated the configuration of this criterion, with stress values, as outlined in Table 5, pertinent to wood-wood and wood-CFRP connections [22]. Additionally, the stress intensity factor for damage, described by Formula (1) [20]. (1) where, σ n , σ s ,σ t based on the maximum stresses nominal stress and transversal directions as outlined in Table 5.…”

Prediction of the ultimate load-carrying capacity of wooden notched beams with and without reinforcements using a splitting model

“…The quasi-brittleness of wood has an effect on the resulting performance, since the energy released by the wooden element is used for damage and crack extension. This type of material can be considered by two different methods, a non-linear one, which is based on the cohesive law (cohesive crack model) [13,33,29,30,39], and a linear one as part of the equivalent Linear Elastic Fracture Mechanics ( EQ LEFM), which considers a Resistance to crack growth-curve (called, R-curve) [4,41,28,26,10].…”