Probabilistic strength prediction of adhesively bonded timber joints

The strength prediction of adhesively bonded timber joints is difficult due to the anisotropic and brittle nature of the adherends, the complex stress distribution as well as the uncertainties regarding the associated material resistance. This paper describes a probabilistic method for the strength prediction of balanced double lap timber joints. The method considers the statistical variation and the size effect in the strength of timber using a Weibull statistical function. The design method presents an explanation for the increased resistance of local zones subjected to high stress peaks as it takes into account not only the magnitude of the stress distributions, but also the volume over which they act. The predicted joint strengths are slightly underestimated compared with the experimental results due to inaccurate upper tail modelling of the material strength by the Weibull statistical distribution. The probabilistic method provides reasonable results for brittle joint failure and has immediate application in the design of adhesively bonded timber joints.