Testing of timber-to-timber screw-connections in hybrid configurations

This paper presents the results of an extensive experimental study on the short-term mechanical performance of timber screw connections comprising different types of fasteners (inserted at 45° and 90° to the grain) and different timber products (solid sawn timber, glued laminated timber, cross laminated timber and laminated veneer lumber) made from both softwood and hardwood species. Fifty-eight specimens laid out in fourteen arrangements were tested under quasi-static monotonic loading. The test configurations were meant to reproduce connections used in timber-to-timber hybrid composite structures for applications in both new constructions and retrofit interventions. Result comparisons regarding connection stiffness, strength, static ductility, residual strength and failure mode are presented and discussed. Additionally, the experimental data are used to check the extents of validity of existing analytical approaches (mainly developed for softwoods) to screw connections comprising hardwood elements. Practical aspects concerning screw insertion into hardwood elements are also addressed within the paper.