Institute for Transportation

A connection consists of two or more members joined with one or more mechanical fasteners. In most wood structures, connectionss are one of the most important, but least understood, components. Connections provide continuity to the members and strength and stability to the system. Connections
may consist entirely of wood members but frequently involve the
connection of wood to steel or other members. Of the failures observed in wood structures, most are attributed to improper connections design, construction (fabrication) detail, or serviceability.

There is a diversity of mechanical fasteners and connections, each having design criteria developed at different times in history. Some design practices are based on substantial research, some on minimal research, some on extrapolated research, and some on rules of thumb. Thus design
practices of mechanical connections in wood structures are fragmented, and can be confusing, contradictory, and have various inherent levels of safety.

This manual is a collection of state-of-the-art information on mechanical connectionss in wood structures. Mechanical connectionss are defined as those where fasteners penetrate the wood; adhesive connections are not included. It is intended to help design professionals apply engineering judgment for those many connection details not covered by standard
design codes. It will provide an overview of current design basis and related research.