Accounting of the thread embedment in timber structures dowel-type joints. Load–slip relationship

Abstract

This work is devoted to the development of a calculation proposal for dowel-type joints in timber structures that takes into account the increase in load capacity due to the use of threaded dowels. While the method is based on acknowledged criteria of structural standards, it also considers the crushed areas that appear in the timber near the zone of contact with the dowel's thread. Thereby, it comes closer to the actual mechanical behaviour of the whole joint when it suffers a relative displacement between its different parts under an external load. The equations proposed in this study to define the load capacity of the joint take into account the rope effect produced by the axial forces arising on the dowel due to the combined effect of bending of the dowel and compression of the timber fibres embedded in its thread. A comparison of the results of the new analytical method proposed with those of a battery of experimental tests is shown.

A hysteresis model for timber joints with dowel-type fasteners

“…Analyses are subsequently repeated and this effect is introduced by increasing the withdrawal stiffness of the nail. Consequently, according to Domínguez et al [47] and based on the profile of the shank, the withdrawal stiffness is doubled up.…”

“…Laterally loaded joints assembled with profiled fasteners exhibit embedding of the timber fibres into the thread of the shank. According to Domínguez et al [47], three stages can be identified. The first one takes place at small displacement amplitudes, when the bearing mechanism is associated to bending of the fastener shank together with compression of the timber fibres.…”

“…As recommended also by Domínguez et al [47], the model simulates the embedding of the timber fibres into the fastener thread by increasing the stiffness of the withdrawal springs. In particular, the same authors suggest increasing the withdrawal stiffness so that the maximum withdrawal capacity of the fastener is attained once the axial displacement exceeds values around the pitch of the thread.…”

“…withdrawal capacity of the nail F ax is defined Embedding of the timber fibres into the fastener thread: (a) prior to load application, (b) crushing without displacement along the fastener axis, and (c) crushing with displacement along the fastener axis (adapted from Domínguez et al[47]). l thr t pen Schematic of the nailed steel-to-timber joint considered in the simulations.…”

Structural Timber Connections with Dowel-Type Fasteners and Nut-Washer Fixings: Mechanical Characterization and Contribution to the Rope Effect

“…The first that the widths b 1 and b 2 increase with the hinge joint angle of the dowel (θ). With small displacements, the angle (θ) and the total width of crushing (b 1 + b 2 ) are smaller [ 32 ]. Initially, it propagates from the corners of the wood causing a cutting effect and increases with the displacement ( Figure 10 ).…”