Analysis of the Stress State at the Cogging Joint in Timber Structures

This paper presents a finite-element-based analysis of carpentry joints between structural timber members. Currently, the design of these joints is conducted by using simplifying assumptions of the stress distribution and of the distribution of forces on the contacting surfaces, and neglects the effect of contact friction between surfaces. Such unrealistic assumptions affect the computation of stresses and the tensile and compressive stress ratio of the joint. This study presents a more realistic approach by conducting a numerical simulation of the behaviour of carpentry joints, which enables optimisation in the geometric definition of this type of joints. Finite element analysis reveals the importance of the effect of friction between the contacting surfaces. In addition, the angle between the members affects the distribution of stresses along the contacting surfaces.