ABSTRACT
ABSTRACT: The paper presents analysis of the stress changes due to creep in statically determinate reinforced wood beams. Each beam consist of glue-laminated timber – section, acting compositely with steel rods, or steel-plate; U-profile, symmetrical or unsymmetrical attached to the upper or lower surface of the beams. The mathematical formulation of this problem involves the equation of equilibrium, compatibility and constitutive relationship, i.e. an elastic law for the steel part and an integral-type creep law for the wooden part. For determining the redistribution of stresses in beam section betweenwood beam and steel part with respect to time “t”,Volterra integral equations of the second kind have been derived, on the basis of the theory of the viscoelastic body of Boltzmann – Volterra. Analytical method, which makes use of Laplace transformation and numerical method, which makes use of quadrature formulae for solving these equations, are proposed. The computer programs are realizes in environment of a high-performance language for technical computing MATLAB®. Some relevant examples with the model proposed are investigated and discussed. In this mathematical model, different creep function are assumed and compared by describing of the time depended behavior of the wood. Finally, this analysis show the way how to be integrated the advantages of the highly perfect model of visco-elastic body, describing the creep of wood, and availability of powerful software products. The proposed methods give us the possibilities for realistic estimates of the behavior of the reinforced glue-laminated wood beams, subjected to sustain service load.
