Reinforcement of dowel type connections

• A good design of dowel type fasteners is essential to ensure safe designs.
• Failures that occur in dowel type connections are mostly brittle.
• Failures encountered occur because of an excess of shear or tensile stresses.
• Self-tapping screws will be the main focus of this report.

A good design of dowel type fastener connections is essential to ensure safe designs for the whole structure and cost effective solutions. With reinforced connections, engineers can achieve better capacity of the connection and safer designs by increasing the ductility of the connection (so-called “capacity design” with a ductile connection to be the weak point). This paper presents an overview of the reinforcement of dowel type connections. Most of the failures encountered in dowel type connections occur because of an excess of shear stresses or tensile stresses perpendicular to the grain in the connection area. Because of the large amount of situations and reinforcement techniques, this report mainly focuses on the reinforcement of dowel-type connections when the dowels are mainly loaded parallel to the grain. For such connections, modes of failure of un-reinforced and reinforced connections, updated design models and the effect of the reinforcement on the ductility of the connection will be presented. Among the various types of reinforcement techniques available, nowadays, self-tapping screws have found a wide field of application and they will be the main focus of this report.