Timber rivets in structural composite lumber

Abstract

Timber rivet connections, originally developed for use with glulam construction, may be a viable option for use with structural composite lumber (SCL) products. Tests were conducted on small samples to assess the performance and predictability of timber rivet connections in parallel strand lumber (PSL) and laminated strand lumber (LSL). The test joint configurations were designed to exhibit "rivet failures"-some combination of rivet yield and bearing deformation in the composite-as opposed to wood failure modes, such as block-shear tear-out or splitting.Results suggest that per-rivet design values should fall between 1 and 2 kN, depending on species and density of the composite and load direction with respect to grain of the composite strands. Timber rivets performed better in LSL than in PSL and better in yellow poplar PSL than in Douglas-fir or Southern Pine PSL; 40-mm rivets in yellow poplar LSL gave roughly equivalent performance to 65-mm rivets in yellow poplar PSL.Comparing rivet yield predictions following the National Design Specification recommendations for round nails and the much simpler approach of using 2/3 the maximum load suggests that the latter approach provides a more consistently reliable evaluation of yield strength for timber rivets.Additional study is necessary to assess rivet connection performance in SCL when rivet density exceeds 1 rivet/in 2 .