Simplified analysis of timber rivet connections

Timber rivets, fasteners for glulam and heavy timber construction, have been used in Canada for about thirty years and recently were adopted by the U.S. National Design Specification for Wood Construction (NDS). Rivet connections can exhibit two failure modes, one of which is fundamentally different from those of other dowel fasteners. Failure can occur when a volume of wood bounded by the perimeter of the closely spaced rivets pulls out from the timber, or via a combination of fastener yielding and localized wood crushing. The code-sanctioned analysis of the wood failure mode for timber rivet connections is so complex that closed form solution is not possible and designers must refer to tabular data for solutions. The code approach to the fastener yield/wood crush failure mode is inconsistent with accepted approaches for other dowel fasteners. The simplified analysis presented here is based on wood failure modes combining shear and tension planes, and is presented in closed form for direct incorporation into design calculations without reference to tables. Results show that the simplified procedure is as accurate as the code-sanctioned procedure for prediction of experimentally measured strengths. Ongoing work will continue the efforts of previous researchers who considered the use of yield theory to predict the strength of connections when wood failure modes do not occur.