Numerical and fracture mechanics-based simulations of brittle failure in dowelled timber connections under in-plane multiaxial forces and bending moment

This study generalises an upscaling modelling approach, originally proposed for connections loaded parallel to the grain, to account for in-plane multiaxial loading of connections. The main objective is to evaluate how the combination of internal forces affects the brittle response of dowelled connections. A Beam-on-Foundation model is implemented to obtain the nonlinear load–displacement behaviour of single fasteners. Such information is assigned to coupled nonlinear springs located at the connection shear planes in a multiple-fastener connection model to capture the stresses in the timber member between the fasteners. The onset of cracks along the grain direction is evaluated using the mean stress approach. The numerical model shows a strong correlation with prior experimental findings and offers an efficient method for predicting crack initiation in multiple-fastener connections. Additionally, limit curves for the interaction of normal force and bending moment are provided for an exemplary connection layout, considering different slenderness ratios and brittle and ductile failure.