Design Considerations for Mortise and Tenon Connections

"The Joint Report"

Here's your chance to buy what is affectionately referred to as The Joint Report, the newest report by Dick Schmidt and Christopher E. Daniels of the University of Wyoming Department of Civil and Architectural Engineering. (This report is available as a free download in PDF format on the Timber Frame Engineering Council website.)


The objective of this research is to determine the strength and stiffness characteristics of timber frame connections in tension. Timber frame connections use wood pegs to secure the tenon within the mortise. The design of these connections is currently beyond the scope of building codes, including the National Design Specification for Wood Construction (NDS). Full-size joints were tested to determine failure modes and to establish minimum edge and end distances that ensure peg failure. These end and edge distances were used to verify a design procedure for satisfying NDS spacing requirements. Peg failure was identified as the preferred failure mode because of the ductility exhibited prior to ultimate failure. Mechanical properties, which included peg bending strength, shear strength, and dowel bearing strength, were also established. An efficient method for establishing dowel bearing capacities for combinations of base material (mortise/tenon) and pegs using springs in series was also developed.

Released in April 1999, this highly technical report is 98 pages long. Major sponsor of the work is the USDA National Research Initiative/Competitive Grants Program, and the co-sponsor is the Timber Frame Business Council.