New Yield Model for Wood Dowel Connections

Abstract

The current National Design Specification (NDS) for Wood Construction design methods for dowel-type connectors are based on four-yield modes for connections in double shear. These yield modes were formulated for use with steel dowels as fasteners. Hence design with nonferrous fasteners, such as wood pegs, common in timber frame joinery, is not addressed. Wood pegs, while large in diameter, are considerably more flexible than steel dowels of the same size. A fifth failure mode is proposed for use with wood pegs. This new failure mode, called Mode V yielding, which is an effective cross-grain dowel failure, has been observed in physical testing as well as numerical modeling. The objective of this paper is to establish a design procedure for the Mode V yielding of pegs. The procedure is calibrated to the level of performance (reliability) expected from the other yield modes. A regression equation to relate the effective cross-grain yield capacity of pegs to specific gravity is also developed for use with the Mode V design equation. A reliability analysis indicates that the proposed Mode V design equation can be used in conjunction with existing NDS yield equations for design of wood doweled connections.