NONLINEAR STABILITY AND IMPERFECTION SENSITIVITY ANALYSIS OF HYBRID TIMBER BEAMS FORMULATED VIA A MECHANISM-BASED ENERGY APPROACH
Main Article Content
Abstract
This paper develops an advanced computational framework to investigate the nonlinear stability and imperfection sensitivity of hybrid three-layer timber beams, specifically composed of high-stiffness Birch faces and a relatively soft Pine core. By employing a rigorous variational energy formulation based on the principle of minimum total potential energy, the study explicitly models the complex interaction between flexural deformations and bending-induced membrane effects under large-scale initial geometric imperfections. A distinctive feature of the proposed model is the derivation of a mechanism-based energy index (η), which provides a robust mathematical criterion for identifying the transition from bending-dominated to membrane-activated structural regimes. The numerical implementation is executed via an efficient MATLAB-based algorithmic procedure, enabling a high-fidelity parametric exploration of imperfection amplitudes ranging from infinitesimal values to L/50. Comprehensive numerical results reveal that substantial geometric deviations lead to a significant "knock-down" effect on structural stability, with tangent stiffness degradation exceeding 60% in the pre-critical stage as the load increases. The analysis of shear stress gradients and interface slip distributions further highlights the susceptibility of hybrid members to local instability when membrane forces are activated. Furthermore, a topographical stability transition map is constructed to visualize the synergistic effects of interlayer slip stiffness and initial curvatures on the global buckling limits. The computational findings offer a robust theoretical basis for the safety-limit design of slender hybrid composite members in modern civil engineering applications, emphasizing the necessity of accounting for large-scale geometric nonlinearities in structural reliability assessments.
Downloads
Article Details
Issue
Section
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
How to Cite
References
Smith, I., & Fraser, T. (2020). Sustainable timber engineering in modern architecture. Building Research & Information, 48(2), 115-128. doi:10.1080/09613218.2019.1661271.
Jones, K. (2021). The rise of mass timber. Architectural Review, 249(1480), 12-18.
Dietsch, P., & Brandner, R. (2015). Serviceability of timber composite members: A review of current design methods. Construction and Building Materials, 92, 2-15.
Fragiacomo, M. (2017). Hybrid wood-based systems: State-of-the-art and future developments. Technical Report, University of Sassari, Italy, 1-45.
Do, T. T., et al. (2025). Experimental study on GLT structures / real-scale application. Lecture Notes in Civil Engineering: Proceedings of the 4th International Conference on Structural Health Monitoring and Engineering Structures, Vol. 747, Springer Nature, 791-801.
Dias, A. M. (2019). Mechanically jointed timber behavior: Experimental and numerical investigations. Engineering Structures, 185, 164-171.
CEN. (2004). EN 1995-1-1: Eurocode 5: Design of timber structures - Part 1-1: General - Common rules and rules for buildings. European Committee for Standardization, Brussels.
Yeoh, D. (2020). Revisiting the gamma method for CLT: Computational improvements and limitations. Journal of Wood Science, 66(25), 1-12.
Nguyen, H. S., et al. (2025). Modelling of Timber-to-Timber Composite Beam using Welded-Through Wood Dowels. Lecture Notes in Civil Engineering: Proceedings of the 4th International Conference on Structural Health Monitoring and Engineering Structures, Vol. 747, Springer Nature, 357-367.
Timoshenko, S. P. (1921). On the correction for shear of the differential equation for transverse vibrations of bars. Philosophical Magazine, Series 6, 41(245), 744-746.
Vlasov, V. Z. (1961). Thin-walled elastic beams (2nd ed.). Jerusalem: Israel Program for Scientific Translations, 1-493.
Shabana, A. A. (2019). Geometric nonlinearity in beam-type structures. Cambridge: Cambridge University Press, 85-112.
Crisfield, M. A. (1991). Non-linear finite element analysis of solids and structures: Vol. 1. Essentials. Chichester: John Wiley & Sons, 1-345.
Reddy, J. N. (2017). Energy principles and variational methods in applied mechanics (3rd ed.). Hoboken: John Wiley & Sons, 215-280.
Nguyen, L. T., et al. (2025). Numerical Modelling of Densified Wooden Nails in Timber Assemblies using Abaqus. Lecture Notes in Civil Engineering: Proceedings of the 4th International Conference on Structural Health Monitoring and Engineering Structures, Vol. 747, Springer Nature, 871-881.
Do, T. T., et al. (2025). Study on the Mechanical Properties of Glued Laminated Timber Members and Performance of Beam-Column Connections. Lecture Notes in Civil Engineering: Proceedings of the 4th International Conference on Structural Health Monitoring and Engineering Structures, Vol. 747, Springer Nature, 881-891.
Rajčić, V. (2021). Timber-timber composite beams: A review of structural efficiency and sustainable performance. Sustainability, 13(10), 5432, 1-22.
Lam, F. (2017). Partial interaction in wood composites: Modeling and performance. Wood Science and Technology, 51(1), 12-28.
Bažant, Z. P., & Cedolin, L. (2003). Stability of Structures: Elastic, Inelastic, Fracture, and Damage Theories. Singapore: World Scientific Publishing, 1-980.
Xu, B. H., & Taazunt, M. (2020). Numerical analysis of the nonlinear behavior of hybrid timber beams with imperfect interfaces. Construction and Building Materials, 258, 119561, 1-14.