The mechanical behaviour of timber structures is significantly influenced by the stiffness, load-carrying capacity and ductility of the joints. This study is focused on the stiffness of dowelled steel-to-timber joints, which were subjected to tensile loadings at different orientations with regard to the grain direction (0°, 30°, 45°, 60° and 90°). The values of the joint stiffness in service obtained from the tests were compared with predictive values from current design codes (Eurocode 5 and NDS). The current design codes showed their weak predictive ability. Besides timber density and fastener diameter, as well as clearance and friction between the joint members, orientation of load with respect to timber grain and dowel slenderness ratio are also the important factors that affect the stiffness of a joint. An empirical expression of stiffness for steel-to-timber joints with single dowel was proposed on the basis of the formula in Eurocode 5 and the Hankinson-type formula using non-linear fitting of the experiment results.
The advanced calculation methods for wood structural elements in fire situations proposed by EN1995-1-2 provide reduction factors of wood strength according to the temperature. The values of these reduction factors given for compression and tension strength are relatively well documented. However, the reduction factors of wood shear strength with temperature were not studied. This study concerns experimental investigations conducted to characterize the evolution with temperature of the shear strength of wood. The tests are realized using a specific original specimen specially developed for this study. The experimental results allow evaluating the values given in EN1995-1-2.
