1,720,963 research outputs found
A Comparison of Un-reinforced and Reinforced GlulamTimber with Steel Bars
No full textThis work deals with the development of a series of experimental tests for the
determination of the flexural behaviour of un-reinforced and reinforced beams of glue
laminated (glulam) timber. The reinforcements consisted of steel bars. All the timber beams
were tested to failure in a four point loading set-up. The results showed that the reinforced
beams performed better than the un-reinforced beams, concerning the mechanical strength.
The reinforced beams showed, on the contrary of the un-reinforced beams, consistent
increasing in stiffness and ultimate loads. And, above all, they redistributed the stress field
in the cross-section so they showed a significant spread ductile zone against a brittle zone
in a typical un-reinforced beam. For the reinforced beams the percentage of increase was
25.9 % for the stiffness, 48.1% for the maximum load, and it was 43.8 % for the ductility,
respectively
Prestressed glulam timbers reinforced with steel bars
No full textThis paper discusses a series of four-point bending tests that were conducted to failure on unreinforced, reinforced and reinforced-prestressed glue laminated (glulam) timber beams with steel-bars in a simply-supported scheme to determine their flexural behavior. The cross sectional ratio between the steel and the wood was 0.82%. To increase the level of reinforcement, some reinforced beams were prestressed by applying a moderate force to the lower bar. The experimental and numerical data provided the load-deflection, load-strain relationships and strain profiles of the tested beams. The results of the reinforced beams showed that the mechanical strength, the load-carrying capacity and the stiffness for both the simple and prestressed beams were enhanced compared to the unreinforced beams. For the simply reinforced beams, the stiffness increased by 25.9%, the ultimate load increased by 48.1% and the ductility increased by 43.8%. For the reinforced and prestressed beams, the stiffness increased by 37.9%, the ultimate load increased by 40.2%, and the ductility increased by 79.1%
A finite element method with inter-element interpolation points for thin plate. Part I: Compatible formulation
No full textIn this study, an inter-element point interpolation is introduced within a displacement-based formulation of the Finite Element Method (FEM) to analyze elastic thin plates. The problem domain is discretized using a mesh of rectangular elements, where the deflection field is the sole primary variable. The displacement field is interpolated using quadratic functions, with the flexibility to customize these functions by adjusting the positions of control points either within, along the borders, or outside the mesh elements. This approach ensures continuity between adjacent elements and reduces the overall degrees of freedom in the governing discretized equations. A weak formulation is employed to derive the system of discretized equations, incorporating both displacement and rotational boundary conditions. The FEM formulation is implemented in a computational framework to solve the static problem of an elastic thin plate under a specified load. Numerical applications are conducted to evaluate the performance of the proposed model on isotropic, linear elastic thin plates. The results indicate that the model can accurately reproduce both displacement and moment fields, demonstrating good agreement with corresponding analytical solutions
A finite element method with inter-element interpolation points for thin plate. Part II: Mixed formulation
No full textThis study introduces a new mixed finite element formulation for the analysis of elastic thin plates,
incorporating inter-element interpolation points for enhanced performance and implementation
simplicity. The method utilizes a regular rectangular mesh, where the displacement field is interpolated
using bi-quadratic functions, and the stress field is approximated through bi-linear interpolation. The
quadratic interpolation for displacements is flexibly defined by adjusting the positions of control
points, which can be located within, on the boundaries, or outside, of the mesh elements. This approach
ensures continuity across mesh elements while reducing the degrees of freedom in the discretized
system of equations.
The governing equations are derived by enforcing the stationary of the mixed Hellinger–Reissner
functional. Numerical applications are conducted for isotropic, linearly elastic thin plates subjected to
different loading conditions and boundary conditions. The numerical results demonstrate the high
accuracy of the proposed method in reproducing displacement and stress fields, showing excellent
agreement with analytical solutions and validating its effectiveness
A Finite Element Method orthotropic multi-yield elastic-inelastic model of a wood-adhesive-steel composite
No full textComposite elements made of wood reinforced by adhesively inter-layered steel lamina can be employed as structural
elements in building engineering, thanks to their favorable ratios of strength and stiffness to mass and their ductility.
The mechanical response of such composite, under loading, can be predicted by employing a Finite Element Method
with a proper model of each material. In this work, the Finite Element Method model is formulated within the theories of
Continuum Mechanics and irreversible thermodynamics of deformation, finite strains hypothesis, and kinematics of large
displacements. For the wood material constituent an orthotropic elastic–plastic-damage constitutive law is adopted, to
address the effects of irreversible strains, formulated by a multi-surface yield, both for plasticity and damage, where each
yield surface operates disjointedly each other, at the level of stress–strain component. The validity of the proposed model
and its computational technique is revealed by analyzing the stress–strain path until the failure of a composite element.
Thus, the numerical results are compared with the experimental data obtained in a tension test of that composite element.
The proposed model adequately represents the mechanical behavior of the composite
A multi-linear material based FEM for nonlinear analysis of steel-reinforced glulam timber
No full textThe present paper deals with the development and application of an implicit nonlinear finite element model for analyzing glulam-laminated (glulam) timber
beams, reinforced with steel bars. A generalized material model is built in a FEM code that can simulate the mechanical behavior of a solid under various
type of loading and thermal history. The ability of the model is to schematize the nonlinear behavior, of the interacting materials: glulam timber, adhesive
and steel bar, with a multi-linear, piecewise, stress-strain curve for each three-dimensional components of the stiffness tensor, without the need of
plasticity theoretical function. This feature habilitate us to properly use this procedure for wood which shows an high anisotropy, affected by a complicate
nonlinear behavior, difficult to introduce in a numerical simulation model. Thus, this more adequate representation of the material mechanical
characteristics can improve the numerical simulation of material responses. A similar concept was used by other authors representing the stress-strain
law, with power functions that fits the measured values from material tests. In the present study wood is schematized as orthotropic material, then the
representation of the stress-strain curves is obtained by fitting the raw data measured from experimental tests. The numerical procedure has been applied
to analyze a beam made of a wooden glulam, reinforced with steel bar, that is statically loaded in a four-point experimental set-up. The solution of the
problem is obtained by an approximate Newton-Raphson iterative procedure, due to the nonlinear nature of the equations, in which load has been
discretized into a finite number of steps. A software routine is developed for the material representation and implemented in a general FEM, which is
capable to simulate the mechanical behavior of a solid undergoing large displacements and deformations. The numerical results have been compared
with those of some experimental tests obtained in a previous work. The proposed methodology has demonstrated its adequateness to describe the
mechanical behavior of steel reinforced glulam timber, under bending loads. This encourages us to extend the present approach to other more complex
cases, in a future work. Furthermore, this model can contribute, when it is supported by experimental data, to improve current available techniques of
timber reinforcement
Prove di pacciamatura in ambiente protetto mediante l’impiego di film plastici innovativi
No full textImpiego in agricoltura di materiali plastici innovativi a basso impatto ambientale. Potenza 28-29 novembre 2003
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