A numerical study of the effects of stresses induced by moisture gradients in steel-timber dowel joints

This study considered moisture-induced stresses in timber dowel-type joints. It has previously been shown that moisture variations and gradients can affect the load-bearing capacity of structural timber elements (Aicher et al. 1998; Gustafsson et al. 1998; JOnsson and Thelandersson 2005). The explanation is that the moisture-induced stresses interact with the stresses generated by mechanical loading (Figure 1). Typically, the tensile stresses perpendicular to the grain are of prime concern. The aim of the study was to investigate to what extent the load-bearing capacity of steel-timber dowel joints can be affected by moisture gradients. The joint was loaded parallel to the grain (Figure 2a). In Figure 2b, two typical failure modes are presented (Schmid et al. 2002). Jorissen (1998, 1999) has described the influence of tensile stresses perpendicular to the grain and shear stresses on these failure modes. In the present study, only the effect of tensile stresses perpendicular to the grain was evaluated because of their great importance.