| Concerns for improved utilization of the wood supply and sustainability of forest resources has compelled the forest products industry to develop innovative alternative wood products. These manufactured products, known generically and collectively as engineered wood products (EWP), are produced using under-utilized wood species and undersized stems in processes that reduce the raw wood into smaller pieces, then bonds and re-forms them into structural wood products.;In timber structures, bolted connections are one of the most commonly specified types of mechanical fasteners in structural wood design construction in North America. Despite the widespread use of these fasteners with wood and wood-based materials, established design methods are based predominately on the yielding of the bolt or wood and disregard the fracture potential of splitting or shear failure in wood. This issue becomes even more complex when structural composite wood products are introduced as members in the connection systems.;Failure of Eastern white pine [Pinus strobus L.] and structural composite lumber products including laminated veneer lumber (LVL), parallel strand lumber (PSL) and laminated strand lumber (LSL) were investigated in bolted connections under static load conditions, with the focus on identification and characterization of brittle failure mechanisms. Loading was applied in a double shear arrangement, with the wood material as the center member and high strength transparent polycarbonate, GE LexanRTM, as the side members. Use of GE LexanRTM in place of traditional steel side members allowed observation and image capture during the failure process.;Dominant failure mechanisms bolted connections were identified. From the experimental program, it was determined that failure mechanisms were variable among the EWP tested, with LSL fracture behavior different than the others by exhibiting greater resistance to splitting.;A discrete element model using a lattice network approach was developed to predict the fracture process of LSL and Eastern white pine [Pinus strobus L.]. The technique involved representation of these materials by a regular arrangement of discrete elements having enforced nodal connectivity, with the network representing morphological characteristics. The model, based on principals of equilibrium and continuity proved to be an effective representation of the fracture process. |
