Evaluation of fracture performance of bond-lines in adhesive-laminated mass timber products
| dc.contributor.advisor | Gong, Meng | |
| dc.contributor.author | Gao, Zizhen | |
| dc.date.accessioned | 2025-07-31T18:26:20Z | |
| dc.date.available | 2025-07-31T18:26:20Z | |
| dc.date.issued | 2025-04 | |
| dc.description.abstract | Adhesive-laminated mass timber products (ALMTs) are widely used in high-rise timber structures. However, due to the unique properties of wood as a biomaterial, discontinuities such as drying cracks, adhesive deficiencies, holes, and notches often occur in ALMTs during production and application, leading to stress concentrations that make understanding the fracture performance of bond-lines critical for ensuring structural safety. Fracture mechanics, which uses the stress intensity factor (K) and energy release rate (G) to characterize fracture behavior of materials, provide a reliable way for evaluating the fracture performance of ALMTs. This study comprehensively investigated the mechanical and fracture performance of ALMTs. A novel method coupled with the digital image correlation (DIC) technique was developed to assess the in-situ elastic properties of bond-lines. Additionally, the J-integral method was employed to study fracture toughness under Mode I, Mode II, and mixed-mode loading. Three commonly used structural adhesives, namely polyurethane (PUR), emulsion polymer isocyanate (EPI), and phenol–resorcinol–formaldehyde (PRF), were tested with white spruce (Picea glauca) and sugar maple (Acer saccharum) adherends. Strain distribution along a bond-line was analyzed to determine its modulus of elasticity (E) and shear modulus (S). Results showed that the elastic properties of the bond-line exhibited variability but had minimal impact on stress distribution of ALMTs. In fracture toughness testing, the critical energy release rates (GIC and GIIC) were calculated using J-integral theory combined with full-field strain and displacement data from DIC. PUR exhibited the highest fracture, while EPI and PRF showed moderate toughness. Moreover, under mixed-mode loading (angles from 0° to 90°), PUR demonstrated the highest maximum load (Pmax) and total energy release rate (GTC), highlighting its superior performance for structural applications. EPI and PRF showed lower fracture resistance under low-angle mixed stresses, indicating potential limitations in scenarios where such loading conditions dominate. Furthermore, this study highlighted the critical role of optimizing adhesive-adherend combinations to balance strength, fracture resistance, and material compatibility. These insights contribute to advancing the understanding of bond-line mechanics and fracture behavior in ALMTs, offering practical guidelines for improving the structural safety, durability, and sustainability of mass timber products in modern construction. | |
| dc.description.copyright | © Zizhen Gao 2025 | |
| dc.format.extent | xxiv, 256 | |
| dc.format.medium | electronic | |
| dc.identifier.uri | https://unbscholar.lib.unb.ca/handle/1882/38358 | |
| dc.language.iso | en | |
| dc.publisher | University of New Brunswick | |
| dc.rights | http://purl.org/coar/access_right/c_abf2 | |
| dc.subject.discipline | Forestry and Environmental Management | |
| dc.title | Evaluation of fracture performance of bond-lines in adhesive-laminated mass timber products | |
| dc.type | doctoral thesis | |
| oaire.license.condition | other | |
| thesis.degree.discipline | Forestry and Environmental Management | |
| thesis.degree.grantor | University of New Brunswick | |
| thesis.degree.level | doctorate | |
| thesis.degree.name | Ph.D. |