Load-carrying capacity of dowelled joints with slotted-in steel plate loaded at an angle to the grain

Abstract

Dowelled joints loaded at an angle to the grain can fail in either a ductile or brittle way. In European design standard for timber structures, the load-carrying capacity of dowelled timber joints perpendicular to the grain is determined by the lower value of the ultimate yield load-carrying capacity of the joint with ductile failure mode based on the European Yield Model and the splitting capacity with brittle failure mode based on the fracture mechanics. However, a mixed failure mode can occur with a combination of the splitting of the timber and the plastic deformation of the fasteners. The available empirical formulae for the splitting capacity are mainly derived from the experimental results of the joints with rigid fasteners. This paper presents the tests on the dowelled joints with slotted-in steel plate under tensile loadings at different orientations with regard to the grain (90° and 45°) by yielding fasteners to validate the empirical formulae of the splitting capacity. In order to explicitly determine the failure mechanism of dowelled joints loaded perpendicular to the grain based on load-carrying capacity, the initial yield load-carrying capacity of the joint based on the European Yield Model (EYM) is proposed, from which the plastic deformation begins to occur in the embedded zone of the timber and steel fasteners. In practice design, through comparison of the initial yield capacities of the joints proposed in this study, the ultimate yield capacity based on the EYM according to EC5 and the splitting capacity according to DIN 1052, the failure modes can be accurately predicted and the ductility can be qualitatively estimated. The present experimental results together with those from literatures were used to validate the proposed design method.