Multi‐Scale Investigation on the Compressive Behavior and Failure Mechanisms of Post‐Heated Glued Laminated Bamboo

Despite growing interest in engineered bamboo for sustainable construction, the post‐heating compressive behavior and failure mechanisms of glued laminated bamboo (GLB) remain inadequately understood, hindering reliable post‐fire safety evaluations. This paper presents a multi‐scale investigation on the compressive behavior and failure mechanisms of post‐heated GLB. Specimens were exposed to temperatures ranging from 20°C to 250°C and subsequently tested under axial compression at ambient conditions. The study characterizes failure modes, stress–strain responses, mass loss, compressive strength, and elastic modulus, supplemented by thermal analysis, microstructural imaging, and acoustic emission (AE) monitoring. The results reveal a distinct temperature‐dependent transition in failure mechanisms: fiber buckling and mixed‐mode failures dominate below 150°C, whereas adhesive‐layer splitting and brittle fracture prevail above 200°C. Compressive strength initially increases up to 150°C but then drops sharply, attributable to carbonization; conversely, the elastic modulus remains largely unaffected, suggesting that fiber stiffness is preserved after heat exposure. Thermal analysis indicates that the phenolic resin adhesive retards bamboo decomposition and facilitates residual char formation, creating a protective layer that enhances thermal stability. Microstructural evidence confirms progressive pyrolysis of parenchyma cells, interfacial debonding, and adhesive aging with rising temperature, while AE signals consistently corroborate the heightened brittleness of post‐heated specimens. By elucidating the coupled thermo‐mechanical pyrolysis mechanisms across multiple scales, this study provides essential experimental data and theoretical insights for post‐fire assessment and rehabilitation of bamboo structures.