Timber Frame Moment Joints with Glued-In Steel Rods – A Designer’s Perspective

Significant evidence based on experimental research exists to give designers confidence in the use of theoretical equations to evaluate the pull-out strength of threaded steel rods glued into timber. However the mechanism of load transfer through a timber frame moment joint utilizing glued-in steel rods requires more than understanding simply the tension performance of a glued-in rod. This paper presents a method of evaluating joint strength for moment and axial forces based on traditional mechanics theory adapted for use with timber. It takes into consideration the effects of time dependant deformation in timber at bearing interfaces and considers also the effects of stress concentrations imposed by the steel rods on the timber. The approach provides a methodology for joint design that has been successfully used in many projects.