Analysis and Design of Griplam Nailed Connections

A stress analysis for Griplam nailed connections is presented for loads parallel and loads perpendicular to the grain. For loads parallel to the grain, two modes of failure are studied: (1)Yielding of the nails in bending with simultaneous bearing failure of the wood under the nail shanks; and (2)wood failure around the group of nails. Maximum stresses in the wood are determined in terms of geometrical parameters of the connection: number of rows of nails, number of nails per row, nail penetration length, spacing of nails, and distances between the nail group and edges of the timber member. Ultimate loads are derived for both modes of failure and allowable loads are determined. For the second mode, Weibull's theory of brittle fracture applied to the longitudinal shear strength of wood is used. Good agreement is shown between theoretical failure loads and full-size connection test results using Douglas-fir. Design procedures are proposed.