Efficient Numerical Modelling Technology of Timber Post and Beam Frame Robustness

The structural strength requirements for timber buildings have been significantly tightened in the second generation of Eurocodes (EN 1990:2023, EN 1991-1-7), which poses a particular challenge for solid timber frames with a beam-and-column structure, where the transfer of tensile forces via dowel connections is inherently limited. This article presents an effective two-scale finite element method (FEM) modelling framework for assessing the strength of such frames during column removal. At the connection level, a continuous fracture mechanics model is used, based on a modified quadratic Hashin-type failure criterion, combining non-linear FEM up to peak load with post-peak behaviour defined in accordance with Eurocode 5. At the overall frame level, multi-fibre beam elements accounting for plasticity and damage, non-linear connection elements with six degrees of freedom interaction, and an element erosion method have been implemented. Both levels have been verified against published experimental data. Modelling at the joint level reproduces measured strength and stiffness values with an error of no more than 5% and corresponds to the characteristic values of Eurocode 5, second edition. Modelling at the frame level accurately reflects the non-linearity of the ‘load-displacement’ relationship, the sequence of joint failure, and the axial forces in the chain line under large displacements exceeding 390 mm. The proposed methodology demonstrates high potential for the practical design of structures in accordance with the current Eurocode provisions on reliability.