Performance of Nailed Gusset Joints in Ridged Timber Portals

The structural behaviour and performance of nailed plywood gusset knee joints of timber portal frames are investigated. An analytical study has shown, and experimental study has confirmed, that the behaviour of the joints in terms of strength and stiffness, distribution of stresses, and rotation of nail groups within the gusset haunches, is directly related to the joint's component arrangements, plywood grain orientation and the dowel action of the nails. An empirical method is presented which permits calculation of the short-term ultimate strength of plywood gusset plates, for various component arrangements of the knee joints, based on the strain distribution along the critical section of the haunched gussets. It is shown that a considerable gain in ultimate strength and performance can be achieved if a correct joint configuration is used