Numerical analysis, experimental tests and non-linear analytical models in the study of bent timber beams reinforced with FRP strips

Abstract

The paper presents selected methods for modelling bent timber beams strengthened with fibre-reinforced polymers (FRP). The assumptions are described, and the main analytical models representing the non-linear bending behaviour of wood are shown. Based on the models presented, analytical approaches considering reinforcement in the tension zone are proposed. The problem of determining the appropriate material parameters of the wood used in analytical calculations and numerical models is discussed. The main numerical methods used in timber analyses are presented. The Hill yield criterion and the generalised Hill yield criterion are discussed in more detail. A method for retrospective estimation of material properties of wood taking into account non-linear material models and fitting the generalised Hill yield criterion is described. Experimental bending tests of technical-scale beams reinforced with composites are presented. The numerical analysis was carried out and discussed. The generalised Hill yield criterion was applied to represent the behaviour of the wood, distinguishing the different yield stresses in compression and tension. The suitability of using non-linear models and advanced strength criteria in the numerical analysis of timber elements is discussed.