Ductility Aspects in Nailed Glue Laminated Timber Connection Design

Abstract

A nailed joint system, comprising of two slotted-in steel plates with shot-through smooth round steel nails in glulam, was analyzed from the viewpoint of an engineering description of the ductility behavior. Experiments on 15 specimens, with 10 nails in each specimen, were performed. Based on the results, a model describing the ductility behavior is proposed. Ductility is defined as the ratio of ultimate-to-elastic deformations with the ultimate deformation defined as the first load drop corresponding to wood splitting. The model is based on “engineering” parameters and estimates the engineering ductility from the slenderness ratio, timber density, and the fastener yield strength in bending. The model is compared with similar experiments in the literature and the validation shows correlation. The method of solution, based on the plastic theory of the European yield model for dowels, is general, and is applicable to other timber-to-timber or timber-to-steel dowel-type connections. The engineering ductility philosophy can give engineers a tool to assess ductility for connections in timber structures.