A Creep Non-Linear FEM Analysis of Glulam Timber

Abstract

This work is focused on a creep formulation in bending for timber beams, of glue laminated (glulam) type, which is suited to be\ud implemented in both geometrical and material non-linear finite element method (FEM) models. It studies the performance of timber beams by accounting the deformation under increments of time and stress in the long term. The proposed creep formulation uses a power-law function expressing the creep strain by means of one coefficient and two exponents. This function needs a fewer number of material coefficients than a classical mathematical analysis of non-linear viscoelasticity, so design applications, such as FEM codes, may more simply describe the deformations in the long term. The formulation has been developed for cantilever beams made of glulam timber using experimental tests in bending and accounting the relations between strains, and both time and tension progresses. Also, the timber creep law has been numerically tested by FEM code runs, with large displacements and large strains assumptions, and further compared with a Navier analytical model. The scatters between experimental and analytical values, and FEM numerical values have reached a standard deviation of 4.06 and of 7.66%, respectively. The acceptable agreement in the comparison between experimental, analytical, and FEM numerical results have demonstrated the capability of the creep formulation to model the behavior in bending of a glulam timber. Also, the proposed creep model has shown an interesting ability to be employed in a FEM code to analyze a timber beam in bending, along time and load evolutions

A Finite Element Method Model for Large Strains Analysis of Timber

“…[6,38] in the present work, are reported in Tables 2 and 3.However,inthis numerical test not any fracture has been considered, by reducing the compressive maximum strains respect to those measured in [6]. The creep parameters assumed from [16] are reported in Table 4. The simulation of the non-linear behaviour of a wood specimen under compression test has been executed by using a finite element mesh of eight node hexahedral elements, with 1000 h.…”

“…Recently, the adoption of FEM numerical codes to analyse the strength of a timber structural member has gained an increasing importance. Often the numerical codes are sophisticated and are specifically capable of representing the non-linear behaviour of the material [12][13][14][15] and some particular effects such as creep [16,17].…”

Modeling the Long-Term Deformation of a Geodesic Spherical Frame Structure Made from Wood Plastic Composite Lumber

“…For instance, a generalized Burger's model was used to describe the creep response of a wood-polypropylene composite in tension [26]. Empirical and generalized viscoelastic one-dimensional (1D) models, for instance, power law models, have been used to describe the creep behavior of WPCs [11,[26][27][28]. A standard nonlinear solid viscoelastic model was used as an analogous model to Prony series to describe the response of the viscoelastic materials in creep [27].…”