Structural Behaviour of Mechanical Timber Connections with Dowel-Type Fasteners in Hardwood: A State-of-the-Art Review

The construction sector contributes significantly to global carbon emissions, prompting a shift toward sustainable engineered timber. However, European hardwood species remain underutilised because current design standards are largely based on research conducted on softwood species. This paper outlines the fundamental principles for designing mechanical timber connections, specifically dowel-type fasteners, by reviewing the European Yield Model and fracture-mechanics approaches for ductile and brittle failure. Through a synthesis of recent experimental investigations on species like European beech, the work identifies critical gaps in current Eurocode 5 (EC5) provisions. The findings demonstrate that EC5 tends to underestimate the load-carrying capacity of many hardwood connections by 33% to 46% and does not explicitly account for brittle mechanisms such as splitting and row shear. Furthermore, the results highlight that connection performance may be significantly increased by factors like dowel-surface roughness, the “rope effect,” and specific assembly requirements such as precise predrilling diameters. This study concludes that existing design frameworks require calibration with hardwood-specific data and improved predictive models to differentiate failure modes. Such adjustments are essential to fully exploit the superior mechanical potential of hardwood species in modern timber construction.