Thermo-mechanical modeling and fire performance assessment of L-shaped timber connections with compressed wooden dowels

A numerical investigation into the thermo-mechanical performance of L-shaped timber connections subjected to fire was made. Two configurations are analyzed: joints reinforced with compressed (densified) wooden dowels and those with solid steel dowels. A finite element model was developed in Abaqus, integrating a three-stage pyrolysis mechanism via a user-defined thermal subroutine (UMATHT) to capture both thermal degradation and mechanical response of wood at elevated temperatures. The simulations predict temperature evolution, char-layer development, and structural deformation under combined thermal-mechanical loading, and are validated against experimental results. Findings reveal that the proposed model accurately reproduces the coupled thermo-mechanical response of timber connections under fire exposure. Moreover, joints with compressed wooden dowels exhibit enhanced fire endurance and superior load-bearing capacity retention compared to steel-dowel counterparts. Overall, the study advances beyond conventional simulations by developing coupled physical models for a novel structural material—compressed wood—thereby contributing to sustainable and fire-resilient structural design.