FRACTURE-ANALYSIS OF BOLTED TIMBER JOINTS UNDER LATERAL FORCE PERPENDICULAR TO THE GRAIN

Crack initiation and propagation in bolted timber joints subjected to lateral forces perpendicular to the grain were analyzed. Mechanical jo ints consisting of spruce (Picea spp.) glued-laminated wood and a sing le bolt of 16 or 20 mm diameter were modeled with the Finite Element M ethod (FEM), and the crack initiation at the boundary of the bolt hole was analyzed by means of average stress criterion. The crack propagat ion parallel to the grain was analyzed by means of Linear Elastic Frac ture Mechanics (LEFM). The energy release rate (G) and the stress inte nsity factor (K) were calculated by changing the crack length of the f inite element model. The critical energy release rate (G(Ic)) and the critical stress intensity factor (K-Ic) in Mode I were obtained by com paring the computed values with the maximum load in the lateral loadin g tests of the joints. The comparison between the experimental and num erical results with several edge distances and bolt diameters showed t hat the LEFM provides a good approximation of the load-bearing capacit ies of bolted joints.