Development of LVL frame structures using glued metal plate joints I: bondquality and joint performance of LVL-metal joints using epoxy resins

Bond quality and joint performance between laminated veneer lumber (LVL) an d metal plates were investigated. Commercially fabricated LVL made of Dougl as fir veneer and bonded with phenol-formaldehyde resin as well as three ty pes of epoxy adhesives were used. Various surface preparations and treatmen ts were applied to ordinary steel, stainless steel, and aluminum plates to remove the weak boundary layer that is incompatible with the resin and form a stable adherend layer that is chemically and mechanically compatible wit h the resin. Small specimens were tested in shear to search the most suitab le metal surface for bonding with LVL. Generally, shear strength obtained f or the specimens bonded with aluminum plates was lower than those bonded wi th ordinary steel plates. Among them chemically treated (ChT) and roughened (R) surfaces have demonstrated superior performance. To investigate streng th performance and bond quality, LVL beams jointed with metal plates were t ested while bending. The best results were obtained for specimens bonded wi th zinc-coated metal plates, though good results were obtained also for ChT and R plates. However, the fracture proved to be fragile when no drift pin s were used, even for highperformance surface treatments. The usage of drif t pins was necessary to add toughness and avoid the brittle status of the f racture.