Load Duration and Seasoning Effects on Mortise & Tennon Joinery

1.4. Objectives <strong>and</strong> Scope
Three primary objectives exist for this research. The first is to determine effects of
seasoning <strong>and</strong> load duration on traditional mortise <strong>and</strong> tenon joints under tension. To the
extent possible, load duration effects are separated from seasoning effects <strong>and</strong> each is
analyzed.
The second objective is to continue the work of Schmidt <strong>and</strong> Daniels (1999). This
research will continue to develop end, edge <strong>and</strong> spacing distances for different species of
wood. This phase of research will also serve in further development <strong>and</strong> validation of a
method in which dowel bearing strength <strong>and</strong> stiffness of a base material loaded with a
wood peg fastener can be predicted mathematically. The advantages of mathematically
predicting strength <strong>and</strong> stiffness could be of great value to future research by eliminating
the need to perform combined material tests.
The third objective is to use results from the long-term joint tests to confirm or
reassess detailing procedures for design of mortise <strong>and</strong> tenon joints. If appropriate a load
duration factor could then be defined for use in connection design to adjust for load
duration effects on strength.
The scope of the long-term research is inclusive of four different species of wood:
southern yellow pine, Douglas fir, white oak, <strong>and</strong> eastern white pine. During the longterm
load study, loading ranged from no load on specimens in the control groups to
sustained load of 1000 lb or 2000 lb on the remaining specimens. The magnitude of the
long-term load is dependent upon the short-term strength of the joints.
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