September 12, 2019
Fasteners used in lateral connections may be used either perpendicular to the shear plane, where the screws are primarily loaded in shear or inclined towards the shear plane, where the screws are axially loaded. ASSY self-tapping fasteners are manufactured with hardened steel providing high capacity and ductility depending on how they are installed. It is important for the designer to understand the different behaviours between the two major types of lateral connections using ASSY self-tapping screws.
Partially threaded self-tapping screws are typically used for connections loaded in shear to provide a more cost-effective connection. Generally, these connections have lower design values, but higher ductility which leads to good energy dissipation properties (Figure below).
Fully threaded self-tapping screws are typically used for connections with inclined axially loaded screws, to provide high withdrawal resistance in both the main and side members. This type of connection is characterized by higher design values and smaller deformations (Figure below). This screw arrangement is a great solution for connections where the deformation is limited.
To find more information on the design of lateral connections using axially loaded inclined screws in Canada, you can refer to the following technical blog post: How to calculate the design strength of inclined screws in Canada. For more detail on the design according to USA standards, you can refer to the following post: How to calculate the design strength of inclined screws in the United States.